ELEGT110111C. Servicing & Technology November Pick and place and holding fixtures. Whatever happened to if transformers

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1 THE PROFESSIONAL MAGAZINE FOR ELECTRONICS AND COMPUTER SERVICING ELEGT110111C Servcng & Technology November 1995 Pck and place and holdng fxtures Whatever happened to f transformers 0.S $ > Q.^

2 1-CLO I er fra IL t.li m MODEL A 30 %DCV ACCURACY RESET. Meet the new TEST BENCH' DMMs, wth more of what made the orgnal a best seller. B-0( PRECISION's orgnal TEST BENCH testers became overnght best sellers because they fused the power of many nstruments n one compact meter. These new models also out -feature ordnary DMMs, and outperform them as well. All are ruggedzed, offer long battery lfe and carry a three-year warranty. Wth True RMS, 41/2 dgt, 20,000 counts and 0.05% DCV accuracy, the Model 391 s a BEST BUY. Now you can have very hgh accuracy, extra resoluton and True RMS readng at a very affordable prce. The Model 391 Test Bench DMM also has frequency, logc, duty cycle and data hold. It's even water resstant. There's a TEST BENCH DMM to ft every applcaton and budget. Choose from three, 33/4 dgt TEST BENCH DMMs, startng wth the Model 388A. All measure AC/DC voltage or current, ohms, frequency, logc levels and test components and contnuty. The Models 389 and 390 add 41 segment bar graphs for smooth peak, null or level adjustments; Mn/Max, memory and relatve modes. The 390 also has a temperature probe. So why carry an ordnary DMM, when you can grab a TEST BENCH! See your local dstrbutor for mmedate delvery. 01,1 PER7N A4c, YEAR WARRANTY MAX FUSED lopov cmor ANALOG BAR GRAPH CAPACITANCE FREQUENCY LOGIC LEVEL TEMPERATURE RUGGEDIZED, RUBBER BOOT PRICE $179 $159 $139 $119 THe O O MAXTEC INTERNATIONAL CORP. Domestc and Internatonal Sales 6470 W Cortland St., Chcago, IL FAX: Crcle (. -9) on Reply Card

3 Contents Volume 15, No. 11 November 1995 PINCUSHION TRANSFORMER page 6 FEATURES 6 Solderng & desolderng update By Edward Zamborsky ES&T takes an n-depth look at solderng and desolderng. The artcle covers how to select the solderng system that s rght for you and the job you are tacklng, how to remove and replace SMDs, and much more. 14 Whatever happened to f transformers By Steve Babbert The advantages and dsadvantages of transformer technology are explaned n ths artcle. 21 Pck and place and holdng fxtures By The ES&T Staff By usng the devces descrbed n ths artcle there's less chance that any components or tracers wll be damaged durng servcng. 22 The TV color sgnal By Lamar Rtche Ths contnuaton of the "Televson theory" artcle from the June ssue descrbes how color was added to the televson sgnal whle allowng monochrome TV recevers to receve the same sgnal wthout t. THE PROFESSIONAL MAGAZINE FOR ELECTRONICS AND COMPUTER SERVICING ELEOTIMIle Servcng & Technology page Vacuum tubes revsted By Arthur Flavell Vacuum tube applcatons have declned dramatcally and whle obsolete n many current applcatons, they have not dsappeared. 30 Interrupted agan! Installng adapter cards n a mcrocomputer By John A. Ross Installng adapter cards n a mcrocomputer can be a dffcuh task because of the demands that they put on the resources that are avalable. Ths artcle dscusses the ways to get around those problems when they occur. 46 Servcng TV horzontal foldover problems By Homer Davdson Horzontal foldover problems n TV sets are not as common as vertcal foldover, but when t occurs you must be able to recognze the symptoms and know the possble defectve components. 51 Constructng a pencl probe By Roger D. Redden Constructng the probe descrbed n ths artcle can help wth some of those naggng connecton problems. DEPARTMENTS 2 Edtoral 4 News 5 Lterature 25 ES&T Calendar of Events 33 Profax 57 Photofacts 58 What Do You Know About Electroncs? Vacuum tubes 59 Test Your Electroncs Knowledge A mxed bag 60 Computer Corner Is computer repar n your future? 63 Books 65 Products 69 Classfed 70 Readers' Exchange 72 Advertsers' Index ON THE COVER Mnuscule electronc components such as SMDs leave consumer electroncs servce centers wth few solderng/desolderng optons. The servce center should have avalable solderng equpment that s capable of removng devces wthout damage to the crcut board or surroundng components, and solderng n replacement devces wthout damage. (Photo courtesy Amercan Hakko) November 1995 Electronc Servcng & Technology 1

4 Edtoral The more thngs change There's an nterestng juxtaposton of artcles n ths ssue. There are two artcles that dscuss one of the oldest technologes avalable to electroncs: vacuum tubes, and one that dscusses one of the most modern technologes that has been ncorporated nto consumer electroncs products: the SAW (surface acoustc wave) flter. Ths s one of the aspects of the study of electroncs that keeps t endlessly fascnatng, as well a lttle frustratng. It's nterestng to learn about the new technology, and at some pont you feel as though you can go ahead and forget about the older technology, lke tubes, but then lke the Glenn Close character n Fatal Attracton they keep comng back, just when you thought they were dead. For example, as Arthur Flavell ponts out n "Vacuum tubes revsted," n ths ssue, "whle obsolete n many current applcatons, vacuum tube technology has not dsappeared entrely. Some types of equpment, such as rado transmtters and muscal nstrument amplfers stll use tubes. The cathode ray tube dsplays n televsons and computer montors are vacuum tubes, whle magnetrons are vacuum tubes that are used n radar and mcrowave ovens." Concdentally, n the "What Do You Know About Electroncs" n ths ssue, enttled "Vacuum tubes," Sam Wlson dscusses vacuum tubes that are used n broadcastng and n audo systems and decres the fact that vacuum tubes are completely gnored n the FCC General Rado Operator Lcense (GROL) test. Sam also resurrects the runnng argument over whether tube -based audo systems sound better than ther sold-state counterparts. On the other sde of the con, n the artcle "SAW flters: Whatever happened to f transformers" Steve Babbert talks about one of the more recent, less well understood components used n consumer electroncs: the surface acoustc wave flter. In ths artcle, Babbert states that n most cases of nnovaton n electroncs technology, such as the ncorporaton of thousands of devces nto a sngle IC, the theory of operaton of the devces remans the same. "Occasonally, however," Babbert contnues, "a new devce wll be developed that wll take the place of one or more components by utlzng a totally dfferent concept." "The SAW (surface acoustc wave) flter s one devce that employs an entrely new technologcal concept when t comes to provdng flterng. A smple SAW flter can elmnate the need for most of the nterstage couplng transformers, and traps used n vdeo f (ntermedate frequency) strps. These transformers and traps are the components that were used for sgnal couplng and waveshapng." The artcle goes on to descrbe how SAW flters are desgned and constructed and how they work. Whle t's unlkely that a techncan wll fnd both vacuum tube technology and SAW flter technology n the same product, t's not beyond the realm of possblty that he mght encounter both technologes n a sngle day. It wll be nterestng to see how some of the nnovatons n technology that are beng ntroduced today wll be thought of n the future. For example, some of the more recent developments n vdeo dsplay technology are sure to be compared wth each other down the lne. Wll LCD dsplays, for example, ever be able to replace CRTs? How about some of the more advanced technologes that are stll under development such as plasma dsplays or the dgtal mrror devce? I can't help but wonder f sometme n the future a couple of vdeo enthusasts wll be sttng down watchng an LCD dsplay or a DMD dsplay, or even some knd of dsplay technology that hasn't even been dreamed of yet, and one of them wll comment that, yes, t looks good, and crsp and sharp, but t just doesn't have the warmth, the realsm of a CRT. And then the whole argument about the qualtes of one technology vs another wll start up, just as t has over the sound of tubes vs transstors n audo systems. csaa.04 ec1.s..,d 2 Electronc Servcng & Technology November 1995

5 THE PROFESSIONAL MAGAZINE FOR EL EC TRONCS AND COMPUTER SERVICING ELECTROING Servcng & Technology Electronc Servcng & Technology s edted for servcng professonals who servce consumer electroncs equpment. Ths ncludes servce techncans, feld servce personnel and avd servcng enthusasts who repar and mantan audo, vdeo, computer and other consumer electroncs equpment. EDITORIAL Nls Conrad Persson, Edtor Krste A. Wckham, Assocate Edtor Rchard S. Moseson, NW2L, On -Lne Coordnator CONSULTING EDITORS Homer L.Davdson, TV Servcng Consultant Vctor Meeldjk, Components Consultant John E. Shepler, Audo Consultant Sam Wlson, Electroncs Theory Consultant PRODUCTION Elzabeth Ryan, Art Drector Barbara Terzo, Assocate Art Drector Susan Olver, Assstant Art Drector Edmond Pesonen, Electronc Composton Mgr. Dorothy Kehrweder, Producton Manager Emly Kreutz, Assstant Producton Manager Pat Le Blanc, Phototypographer BUSINESS Rchard A. Ross, Publsher John Dorr, General Manager Frank V. Fuza, Controller Smon Schatzmann, Crculaton Drector Catherne Ross, Crculaton Manager Melssa Ntschke, Operatons Manager Carol Lcata, Data Processng Dense Pyne, Customer Servce SALES OFFICE Electronc Servcng & Technology 76 N. Broadway, Hcksvlle, NY ; FAX Dane G. Klusner, Drector of Advertsng Emly Kreutz, Sales Assstant EDITORIAL CORRESPONDENCE: P.O. Box Overland Park, KS NESD1%,.. Member, Electronc Servcng Dagen Assocaton Electronc Servcng & Technology (ISSN ) s publshed 13 tmes a year by CO Communcatons, Inc. 76 N. Broadway, Hcksvlle, NY Telephone (516) Second class postage pad at Hcksvlle, NY and addtonal offces. Subscrpton prces (payable n US dollars only): Domestc-one year $24.75, two years $45. Foregn countres-one year $30.75, two years $57. Entre contents copyrght 1995 by CO Communcatons, Inc. Electronc Servcng & Technology or CO Communcatons, Inc. assumes no responsblty for unsolcted manuscrpts. Allow sx weeks for delvery of frst ssue and for change of address. Prnted n the Unted States of Amerca. Postmaster: Please send change of address notce to Electronc Servcng & Technology, 76 N. Broadway. Hcksvlle, NY CO Communcatons, Inc. s publsher of CO The Rado Amateur's Journal, Popular Communcatons, Mcro - Computer Journal, CO Rado Amateur (Spansh CO), CO Amateur Rado Equpment Buyer's Gude, CO Amateur Rado Begnner's Buyer's Gude. Popular Communca-tons Communcatons Gude, and Electronc Servcng & Technology. Now there s a fast, safe, effectve way to gve contamnants the brush-off. The new BrushCleanTM System combnes powerful.solvents wth the gentle scrubbng. acton of a brush. Use three ways: spot clean economcally wth the brush, flush under SMDs wth the extenson tube, or clean large areas wth the spray nozzle. Three powerful tools - one convenent package. Th Solutons Source. Name Company Phone Street Address GC Fee Flux -Off 2000 Cleanng system quckly and completely removes R, RMA, RA and synthetc flux. Flux -Off II Propretary alcohol blend cleanng system removes water soluble and all other fluxes quckly. CFC Free Electro-Wash 2000 Fast dryng one step cleanng and degreasng system safe for most plastcs. Pow-R-WashTM Hghly effectve nonflammable precson cleanng system safe for use on metals and most cs:4616. The BrushClean System features the new All -Way Spray Valve that sprays n any drecton, even upsde down! 0 YES! Please send my FREE copy of ChemFactsa comprehensve gude for selectng the rght cleanng products for electrcal and electroncs servce, rework and repar. Fax Ttle Cty State Zp Whch descrbes your busness: 0 Producton 0 Servce and Repar U Other Number of techncans usng the type of cleanng product n ths ad Whch best descrbes your role: L Recommend/specfy products LI Purchase 0 Other? CALL FAX TPAGE m cn Co cr Mal to: Chemtroncs, Inc Cobb Center Dr. Kennesaw, GA Crcle (54) on Reply Card 3

6 News Home theater sales keep up fast pace for second quarter of 1995 Keepng pace wth the records set n the begnnng of the year, factory sales of home theater products rose 8 percent n the second quarter of 1995, accordng to the Consumer Electroncs Group of the Electronc Industres Assocaton (EIA/ CEG). Sales of all home theater products* totaled $1.7 bllon for the quarter, and $3.4 bllon for the frst sx months of the year. EIA/CEG estmates there wll be more than 10 mllon home theater households n the U.S. by the end of the year. "These sales gans show home theater to be one of the hottest consumer electroncs trends for 1995," sad Joyce Flemng, presdent of McCormack Audo Corp. "As evdenced by the huge sales growth of audo products, consumers are movng beyond the vdeo requrements of home theater and are realzng the enormous advantages hgh -qualty speakers and surround sound processors brng." Pushng past the $500 mllon mark, sales of home theater audo equpment ncreased 40 percent for the frst half of the year. Home theater speaker sales for the second quarter jumped a whoppng 155 percent wth a volume of $56 mllon. Speaker sales rose 139 percent for the frst half of the year to $105 mllon. Sales of surround sound processors (recevers, amps and stand-alone unts) were up strongly agan, rsng 37 percent to a second quarter record of $210 mllon and to $396 mllon for the year to date. Overall, sales of home theater audo products rose 52 percent n the second quarter to a total of $266 mllon. H-f VCR sales carred the quarter n the vdeo home theater sde, toppng 27 percent on factory sales volume of $251 mllon. Large screen TV sales (ncludng projecton models) were off two percent n the quarter, whle total home theater vdeo sales edged up three percent to $1.4 bllon. For the year-to-date, home theater vdeo components rose seven percent over 1994 sales and reached $2.88 bllon n volume sales. * Home theater products for these calculatons nclude drect -vew color televsons 25 nches or larger; laserdsc players; projecton televsons; hf stereo VCRs; surround sound processors; amps and recevers; subwoofers; center channel speakers; and satellte surround speakers sold as separate unts or as mult -speaker packages. EIA/CEG research fnds careful shoppng, use of manuals and towerng satsfacton When t comes to consumer electroncs products, Amercans are careful shoppers who read product revews before they go to the store, talk wth knowledgeable sales personnel before they buy, and then read the nstructon manual as they set up and begn usng ther purchases, accordng to a natonal survey conducted by the Consumer Electroncs Industres Assocaton (EIA/CEG). One dvdend of ths dlgence s a tremendously hgh level of satsfacton wth recently -purchased consumer electroncs products, the research found. Specfcally, accordng to the natonal survey of a representatve sample of 750 households, 91 percent are satsfed-ncludng 71 percent who sad they were very satsfed-wth a televson set purchased n the last year. Smlarly, 88 percent are satsfed wth a recently purchased CD player, 84 percent wth a VCR, 81 percent wth a cassette tape recorder, 79 percent wth a telephone answerng machne and 78 percent wth a cordless phone. These make two ponts, sad Gary Shapro, EIA/CEG group vce presdent. One s that the consumer electroncs ndustry s brngng hgh qualty products to market. The other s that the consumers are shoppng carefully and then dong all they can to ensure ther purchase s set up and operatng properly. For example, nearly two-thrds of the respondents sad they do research before purchasng TVs, VCRs, CD players, telephones, computers and smlar products. The two most frequently named sources of nformaton were publshed product revews, whch were cted by 80 percent, and talks wth frends or famly, the choce of 74 percent. Consumers frequently named multple sources of nformaton and added contactng the store, the manufacturer and other organzatons to the lst provded n the survey. One consequence of ths nformaton - gatherng s that 41 percent of consumers sad they always know the exact brand and model they want to purchase before they go to the store, and 16 percent sad they know some of the tme. Once they have made ther purchase, 86 percent reported they read the nstructon manual at some pont durng the frst month of ownershp. Half read the manual whle they set up the product and 38 percent read the entre manual before begnnng the set up process. Nnetyseven percent say they keep the manual after the product has been set up. When the EIA researchers asked how manuals could be mproved, consumers named more dagrams, more detaled descrptons of features and functons, easer to understand language, and a glossary of techncal terms as ther top choces. If there s a problem wth the product, 35 percent of respondents sad they would frst try to solve t themselves. Twentyseven percent would contact the store, 15 percent would ask a frend or famly member for help, and 20 percent would call the manufacturer. In fact, nearly four n ten sad they had called a manufacturer's toll -free number for assstance or other nformaton, and those who called expressed hgh levels of satsfacton wth the servce they receved va telephone. Specfcally 72 percent were satsfed wth the representatve knowledge, 85 percent were satsfed wth polteness, 72 percent wth the speed and 81 percent wth the overall effectveness n solvng the problem. Not surprsngly, 66 percent sad the treatment they receved would nfluence future decsons to buy a product from the manufacturer. The research was conducted through the EIA/CEG Consumer Research Servce n cooperaton wth the EIA Marketng Servces Department. The telephone survey, admnstered by the Verty Group, Inc., has a margn of error of plus or mnus 4 percentage ponts. The research ncluded questons on where consumer electroncs products are purchased, mpact of nstructon manuals on future buyng decsons, reacton to toll -free number experences, evaluaton of automated menus on servce lnes, judgments about warrantes and other purchasng ssues. A full report for the study can be purchased from the EIA Market Research Department. For nformaton call: Electronc Servcng & Technology November 1995

7 Lterature PC -based test catalog The 1995/1996 PC -Based Test Solutons Source Book s now avalable from Geotest Inc. Ths 40 -page products catalog features more than 100 products ncludng hardware, software and systems for PC -Based ATE, data acquston and test and measurement applcatons. Ths catalog contans complete specfcatons, selecton charts and block dagrams. Products nclude the GTXI nstrumentaton chasss for smple, clean and quck confguratons of vrtually any PC -Based ATE, Data Acquston or Test and Measurement confguraton, and the GTPC seres of embedded computer modules n and Pentum confguratons. Crcle (80) on Reply Card Electronc testng and prototypng equpment catalog Global Specaltes ntroduces a 48 - page catalog whch ncludes an nstrument selecton gude and table of contents. Ths full lne catalog features complete product descrptons and specfcatons for ac and dc power supples, functon and pulse generators, frequency counters, capactance meters, logc probes and logc analyss test kts, protolab desgn work staton, project kts, test clps, data acquston products and other global accessores tems. The company's complete lne of prototypng breadboard equpment whch ncludes, solderless quck test and expermentor sockets, proto-board systems, powered protoboards and the famous PB-503 and PB- 503C total breadboard desgn work statons are also featured. Crcle (81) on Reply Card Ste on the world wde web offerng techncal nformaton of fber optcs Fotec has establshed a web ste on the World Wde Web (WWW) as a smple electronc way for those nvolved n fber optcs to get applcatons assstance and product nformaton. The World Wde Web (WWW) s an Internet -based graphcal communcatons system that allows any user wth Internet access to fnd, vew and even download nformaton. Many companes are puttng ther techncal nformaton on the Web to facltate customer access from anywhere n the world 24 hours a day. Ths Web Ste ncludes the company's "Gude to Fber Optc Testng," whch shows the standard test methods used for testng fber optc components and networks, materals and testng product nformaton. Future plans nclude addng the Fotec Fber Optc Testng textbook to the ste n ts entrety. Ths Web ste URL s Crcle (82) on Reply Card Catalog featurng test equpment, tcols, and supples A 48 -page supplement catalog from Contact East comes packed wth hundreds of new test nstruments and tools for engneers, managers, techncans, and hobbysts. Featured are qualty products from brand -name manufacturers for testng, reparng, and assemblng electronc equpment. Product hghlghts nclude new DMMs and accessores, solderng contact east 0 ANL P9-0,11CS TOSERVICI. CLECTIS 16,. actu1.1,11,1ii =Pltarr.$ A MEW from Tektromv 1.70 Mr landhehr OsClloseope s",..9, I M11111W11.: tools, custom tool kts, EPROM programmers, power supples, "create your own tool kt," ELF meters, helpful reference books, mllammeters, megohmmeters, wavemeters, breadboards. Also ncluded are lnes of communcaton test equpment, scope meters, data - corn tools and testers, adhesves, measurng tools, precson hand tools, portable and bench top dgtal storage scopes, solderng/desolderng systems, statc protecton products, ozone safe cleaners, magnfers, nspecton equpment, tool kts and tool bags, workbenches, cases and more. Some brand names nclude Tektronx, Fluke, B&K Precson, Weller, Loctte, 3M, Pace, Htach, Mcrocare and many more. Crcle (85) on Reply Card Electroncs products catalog Herman Electroncs presents the frst edton of the Herman Catalog. Ths page buyers gude contans everythng n electroncs ncludng test equpment, tools, solderng equpment, consumer and ndustral orgnal replacement parts, audo, vdeo and telephone accessores, connectors, computer accessores, batteres, telephone headsets, power products. Crcle (83) on Reply Card Industral electroncs product dgest Galco Industral Electroncs announces a new In -Stock Product Dgest featurng tems that are on the shelf and ready for mmedate delvery. The dgest contans part numbers, quantty -break prcng, product descrptons, techncal specfcatons and a fax back order form. The dgest features tems that customers purchase on a frequent or regular bass. The objectve of ths gude s to provde engneerng, mantenance and purchasng professonals wth all the nformaton they wll need when specfyng or procurng a product, ncludng prcng and techncal nformaton, n one concse and easy -to -use format. Ths new gude provdes quck and easy access to electronc control components and wll reduce the amount of tme customers spend sourcng parts. The company wll update the dgest once a quarter. The In -Stock Product Dgest s ntended to be used n conjuncton wth the company's full -lne product catalog whch s publshed yearly. The full -lne product catalog s over 1,300 pages and features more than 300,000 tems. Crcle (84) on Reply Card November 1995 Electronc Servcng & Technology 5

8 Solderng & Desolderng Update: Process control of SML1 repar By Ed Zamborsky Process control of SMD (surface mount devce) repar nvolves rate of heatng, component algnment and avodance of lead damage. As n all manufacturng procedures, process control s crtcal n achevng consstently good results. Wth repar of SMD components, two functons must be controlled; heatng and component handlng. The "three challenges" of PCB repar nvolve these functons: Rate of heatng. Durng removal and replacement, the rate of heatng must be controlled. Heatng n excess of 4C to 5C/ second ncreases the probablty of component damage due to dfferng thermal coeffcents of expanson (TCE) of the component materals. Moreover, rapd heatng (>5C/second) has been shown to promote substrate delamnaton. Fnally, controlled heatng of the connectons (2C to 3C/second) prevents rapd outgassng of solvents, whch can create solder balls when reflowng solder paste. Component algnment. Durng placement, what dfferentates rework equpment more than any other feature s the ablty of that equpment to repeatably and accurately place components. When dealng wth placement, there are three areas of equpment that should be consdered: basc tools that should be used for component removal only, not placement, tools/equpment for removal and placement lmted to components wth lead ptches of nch or larger, and equpment for removal and placement of components, ncludng fne ptch devces nch or smaller. Lands/lead damage. Damage to lands and leads can occur, usually as a result of operator pressure or rework processes utlzng hand tools. Tools for the repar area There are no generalzatons that can be made wth regard to "deal" tools for an SMD repar staton (Fgure 1). The com- Zamborsky s engneerng manager at OK Industres. Yonkers, NY ponent package and PCB confguraton wll determne the selecton of tools. Here are a few tools that should be consdered. Resstor/capactor "chp" components These components are usually removed and replaced wth new components because of ther low cost. In ths case the preferred approach s to remove wth a contact heatng devce (for speed),.e. tweezer -type handpece; remove old solder usng a solder brad and a solderng ron; depost new solder paste wth a Fgure 1. Ths re -work system features process control to assure proper solder jonts. 6 Electronc Servcng & Technology November 1995

9 Fgure 3. Hot ar pencl for touch up. Fgure 2. Tweezer tp solderng tool. dspenser; place the component wth a vacuum pencl; and reflow the solder paste wth a hot ar tool. Whereas wth each task there s flexblty n the type of tool that can be used, use of hot ar wth solder reflow should be thought of as an absolute. Hot ar reflow wll have a slower rate of temperature rse than a solderng ron (contact heatng). Slower heatng s requred to control problems of dfferental TCE wth the component, whch can nduce crackng. Slower convecton (hot ar) heatng wll also elmnate bolng the solder paste volatles too rapdly, whch can create solder balls. Therefore, the deal tools for ths process nclude a solderng ron (perhaps dual output where a tweezer handpece (Fgure 2), and a standard ron can operate smultaneously), a dspenser for paste, a tweezer or vacuum pencl, and a focused hot ar pencl (Fgure 3). SOIC/PLCC components There s more debate over the repar process of SOIC (small outlne ntegrated crcut) and PLCC (plastc leaded chp carrer) components. Perhaps the greatest pont of contenton s the queston of whch type of heat source s approprate for removal. Manufacturers of contact heatng devces clam that rapd, solated heatng of the leads does not cause any rsk of damage to the component. However, contact heatng devces, whch are usually hand-held, can damage leads through excessve mechancal stress and have been shown to lft pads causng addtonal unnecessary repar. Forced convecton heatng devces elmnate the mechancal stresses caused by contact heatng devces. Furthermore, Cordless POWER Perfect for the bench top or out n the feld Hgh capacty batteres and hgh effcency tps let you solder longewthout rechargng. And a unque, solated -tp desgn el urnates electrcal leaks and damage. A complete lne of rons along wth job -matched tps means you'll fnd the rcn that's perfect for your job. Wrte or call for more nformaton or "where to buy". ISO TIP WAHL CLIPPER CORPORATION 2900 Locust Street Sterlng, IL (815) Fax: (E15) the rate of temperature rse wth equpment or tools that use a closed -loop temperature -controlled system falls wthn component manufacturers' specfcatons. Lmtatons to usng convecton heatng nclude ts relatve neffcency vs. contact heatng where removal may take up to 50 seconds; fve tmes longer than contact heatng. Prccdron " Crcle (66) on Reply Card 7

10 MONITOR MAINTENANCE AND REPAIR MADE EASY! DspulyMateProfessonal VIDEO DISPLAY UTILITIES DsplayMate s the ndustry standard software to dagnose, setup, adjust and mantan vdeo dsplays and ther assoca'ed hardware. The program s easy to use, and s utlzed and recommended by ALL major OEMs and 30 major magazne publshers. Uses for DsplayMate Professonal Dsplay Setup: use the Setup Dsplay test seres to properly adjust the user controls for maxmum clarty and mnm,m eye stran. Testng: There are 300«tests whch evaluate and dagnose Image Dualty, Hardware Compatblty, Speed Performance, Strengths and Weakness', etc. Educaton: There are over 500 pages of documentaton whch explan the use of the software, mantanng and troubleshootng computer vdeo systems, e -c. Even the most techncal user wll beneft Ircm the vast amount of nformaton whch s provded. Fgure 4. Desolderng tool wth wck. LEARN TO TEST, EVALUATE, AND MAINTAIN ALMOST ANY COMPUTER VIDEO DISPLAY!.axIMUCH MUCH 40K FOR MORE INFORMATION AND onn foh 110: ch ASSI ORSPECIALPRICINGCALLUS4 TECH ASSIST. INC th STREET SLITE 105 LARGO FL Crcle ( 6) on Reply Card Factory Drect Aerosols! Fgure 5. A focused convecton tool. 47.1FLUX Evorfo Proven aerosols, wholesale prces. FREE delvery n contnental USA. Most orders shp same day. Safer formulatons. No tme lmt money back guarantee. Dstrbutors welcome. Call Mon -Fr, 8-5 EST hr FREE brochure and tral offers Crcle (63) on Reply Card 8 Electronc Servcng & Technology November 1995 Crtcsm has been leveled aganst forced convecton heatng for ts potental to heat adjacent components. However, those forced convecton systems that focus the hot ar on the component leads vrtually elmnate the potental for unacceptable levels of heatng of adjacent components. Fnally, concerns that forced ar heatng causes component body heatng have been rased. It should be noted that surface mount components are desgned to allow component body heatng. The ssue here s not necessarly component body heatng, but the rate at whch t occurs. Ideal equpment for removal of SOIC and PLCC therefore, depends on the phlosophy (or vested nterest) beng proven. In a vast majorty of cases, the recommended heatng method for removal of SOIC and PLCC packages s hot ar. If the budget for solderng/desolderng tools s lmted, contact heatng s an opton. The same procedures as those used wth chp components may be followed after removal, and therefore, a smlar lst of equpment can be used. Forced convecton tools are also able to smultaneously reflow all leads upon replacement, unlke contact (tweezer type) tps, whch can only be used for removal but not for replacement. Quad Flat Pack (QFP) components The same debate over conducton vs. convecton wll exst when addressng the

11 ssue of a preferred heatng method for removal of QFPs. Agan, after weghng the advantages and lmtatons of each method, forced ar convecton s preferred. Another mportant ssue wth QFP components s that the leads, usually fne ptch, are qute senstve to damage, such as bendng. In the cases where they are beng reused, straghtenng the lead(s) can be very dffcult f they are damaged durng removal. Therefore, a non -contact method of removal becomes more crtcal. The process after removal wll be dfferent for QFPs. Wth chp components, SOIC and PLCC packages t s generally recommended that the old solder be removed and new paste be dspensed. Wth QFP, dspensng s not recommended. Instead, there are two optons you can choose from. You can remove the QFP wth a focused forced ar convecton tool, apply flux and gently use hot ar to level the solder on the pads, and then place and algn the QFP n molten solder (after levelng). Another opton s to remove the QFP wth a focused forced ar convecton tool, use hot ar to level the solder on the pads or level the solder wth specalzed blade - type solderng ron tps, place the QFP and tack -solder leads on two opposte corners, re -apply flux and solder wth a focused forced ar convecton tool. Therefore, the deal tools for QFP should nclude a focused forced ar convecton tool and a solderng staton. LCCC The LCCC (leadless ceramc chp carrer) s a leadless package that requres forced ar convecton for removal, snce there are no leads to conduct heat, and the ceramc package s senstve to rapd heatng. Followng removal, the pads should be cleaned of solder wth wck or a vacuum desolderng tool (Fgure 4), re -pasted wth a dspensng tool and reflowed wth a focused hot ar tool. BGA BGA (ball grd array) components are square or rectangular packages wth ther connectons formed by solder balls underneath the component. Havng no permeter leads to contact wll cause addtonal complcatons to the repar process and possbly some confuson to the repar techncan. The BGA was developed to allow a hgh number of component leads (lke a QFP) at a hgher ptch (lke a PLCC), to reduce the handlng problems (lead bendng / algnment) normally assocated wth hgh lead count devces. Here there s no debate over the requred heatng technology. Focused convecton tools (Fgure 5) are the only possble heatng technque avalable. The component to be removed must be heated through the component body, whle the PCB s heated from the bottom. Lke all SMD components, BGA's are desgned to wthstand hgh reflow temperatures. Controllng the heatng cycle s an absolute requrement when solderng ball grd array components. The focused convecton tool you select for your BGA repars must provde, bottom sde preheatng to a maxmum temperature of 125C, focused convecton heatng at a controlled rate of 2C to 3C/ second wth soak zone to provde thorough component heatng, and a peak zone where the temperature s spked allowng reflow of the solder balls under the component. The fnal stage of the repar profle s the forced coolng of the component beng soldered. In ths step of the process ar bypasses the heatng element to cool the BGA and soldfy the solder at an ( Model 008 DE PORTABLE accelerated rate. Ths forced coolng wll promote a much hgher qualty solder jont wth the relablty of the orgnal manufactured PCB assembly. Removng solder from a prnted crcut board There are two accepted methods for removng solder. The frst method utlzes copper brad for wckng n conjuncton wth a solderng ron. Specalzed solderng ron blade tps are avalable desgned to contact a lnear array of lands, facltatng faster removal. A second method s use of a vacuum desolderng tool. In both cases a temperature -controlled heat source should be used to prevent thermal stress. Replacng the solder on a prnted crcut board There are three technques that are usually used for replacng solder durng an SMD component repar. The most basc method would re -use the exstng solder. Here the techncan uses a solderng ron and wre solder to re -tn the component pads pror to re -placng the SMT component. You.hould keep n mnd that the IS NOW WELL IN HAND Hakko's new Model 808 s a portable desolderng tool wth a bult n pump. The unque desgn places the pump and motor above, not nsde the grp. Ths mnmzes vbraton and makes the grp easy to hold. Replacement parts are nexpensve and mantenance s smple. For more nformaton call, wrte or FAX; Call 1-(800) 88 HAKKO, FAX (805) L1K0` AMERICAN HAKKO PRODUCTS, INC. CORPORATE OFFICE Anza Drve Santa Olarta, CA 91355, U.S.A. Crcle (51) on Reply Card 9

12 These flow charts llustrate the requred steps n solderng/desolderng varous types of components. "CHIP" COMPONENT REWORK: SOLDERING IRON APPLY FLUX HEAT USING SPECIALIZED SOLDERING TIP /I! REMOVE COMPONENT REMOVE OLD SOLDER CLEAN RESIDUE APPLY SOLDER PASTE ALIGN AND PLACE COMPONENT V REFLOW WITH HOT AIR PENCIL CLEAN & TEST "CHIP" COMPONENT HOT AIR APPLY FLUX HEAT USING HOT AIR l REWORK: REMOVE COMPONENT REMOVE OLD SOLDER f CLEAN RESIDUE APPLY SOLDER PASTE ALIGN AND PLACE COMPONENT REFLOW WITH HOT AIR PENCIL CLEAN & TEST SOIC/SOJ REWORK: HOT AIR APPLY FLUX /I! HEAT USING HOT AIR REMOVE COMPONENT /IV REMOVE OLD SOLDER v CLEAN RESIDUE APPLY SOLDER PASTE DOTS ALIGN AND PLACE COMPONENT T REFLOW WITH FOCUSED HOT AIR CLEAN & TEST "CHIP" COMPONENT REWORK: THERMAL TWEEZER APPLY FLUX HEAT/REMOVE COMPONENT WITH THERNAL TWEEZER REMOVE OLD SOLDER CLEAN RESIDUE APPLY SOLDER PASTE ALIGN AND PLACE COMPONENT REFLOW WITH HOT AIR CLEAN & TEST SOIC/SOJ REWORK: THERMAL TWEEZER APPLY FLUX HEAT /REMOVE COMPONENT WITH THERMAL TWEEZER REMOVE OLD SOLDER CLEAN RESIDUE APPLY SOLDER PASTE ALIGN AND PLACE COMPONENT l REFLOW WITH HOT AIR CLEAN & TEST REWORK: WITH PASTE APPLY FLUX HEAT WITH HOT AIR REMOVE COMPONENT REMOVE OLD SOLDER CLEAN RESIDUE APPLY SOLDER PASTE IN A CONTINUOUS BEAD AROUND LAND PATTERN REFLOW WITH FOCUSED HOT AIR CLEAN & TEST 10 Electronc Servcng & Technology November 1995

13 QFP REWORK: HOT AIR, WITHOUT PASTE QFP REWORK: SOLDERING IRON PLCC REWORK: THERMAL TWEEZER APPLY FLUX HEAT WITH HOT AIR REMOVE COMPONENT LEVEL AND RE -TIN LANDS CLEAN APPLY PASTE FLUX ALIGN AND PLACE COMPONENT APPLY FLUX t HEAT AND REMOVE WITH IRON AND SPECIAL QFP TIP REMOVE OLD SOLDER V CLEAN LANDS v APPLY SOLDER PASTE IN A CONTINUOUS BEAD AROUND LAND PATTERN 4, ALIGN AND PLACE COMPONENT v REFLOW WITH HOT AIR APPLY FLUX HEAT AND REMOVE COMPONENT WITH THERMAL TWEEZER CLEAN RESIDUE DISPENSE SOLDER "DOTS" ALIGN AND PLACE COMPONENT REFLOW WITH HOT AIR CLEAN & TEST REFLOW WITH FOCUSED HOT AIR REWORK PROCESS STEPS CLEAN & TEST APPLY FLUX PLCC REWORK:HOT AIR APPLY FLUX HEAT WITH HOT AIR + REMOVE COMPONENT REMOVE OLD SOLDER CLEAN RESIDUE APPLY SOLDER PASTE IN A CONTINUOUS BEAD AROUND LAND PATTERN ALIGN AND PLACE COMPONENT REFLOW WITH HOT AIR CLEAN & TEST HEAT AND REMOVE COMPONENT REMOVE OLD SOLDER CLEAN RESIDUE APPLY SOLDER PASTE PLACE COMPONENT HEAT V CLEAN INSPECT YES NO CONTACT (CONDUCTION) LEVEL LAND (RE -TIN IF NECESSARY) APPLY FLUX OR NON -CONTACT (CONVENTION OR IR) November 1995 Electronc Servcng & Technology 11

14 ugged By The Hgh Cost of SMD Removal? Use PRB Lne CH1PQUIK TM SMD Removal Kt Breeze through the removal process: 1) Apply Flux 2) Melt Chp QukTM alloy on leads wth a low temperature solderng ron 3) Remove SMD 4) Clean up PC board Kt ncludes: Specal Desolder/Alloy Specal Flux Solder Removal Brad Complete Instructons Part#: CQ123 QUlk,Stck $ S No Clean Rework Paste Manufactured wth the hghest qualty. vrgn pre -alloyed sphercal powder No refrgeraton requred No specal atmosphere or shppng requred One year shelf lfe Hgh qualty no clean solder paste wth excellent wettng and solderablty Undergoes strngent qualty control and end product testng Meets federal specfcaton QQ5571 Exceedes Bellcore specfcatons Convenent 12g or 24g 10cc syrnge Note: Paste s not recommended for stencl applcaton. Part# Prce S290 (12g) $6.59 S291 (24g) TM Quantty Dscounts are Avalable. Order from your+ nearest PRB Lne Dstrbutor or call... ELEC RONICS COMPANY For 24 Hour Orderng Phone: Fax: Fgure 6. Flud dspenser for solder paste. tech wll be placng the component onto hard smooth solder, ths may make realgnment dffcult as the part may slde off the solder bumps. The applcaton of a hgh vscosty paste flux wll help stablze the part and promote proper wettng and fllet formaton. A more advanced technque that s especally popular when reparng fne - ptch QFPs s hot ar levelng of the solder pror to replacng the QFP. After the defectve component s removed wth a focused convecton tool, the techncan wll apply flux to the pad array, lower the convecton nozzle and apply heat. Ths heatng operaton wll smooth out any solder spkes left on the pads and facltate component algnment. Apply paste flux to help stablze the part and promote proper wettng and fllet formaton. Some facltes wll elect to completely remove the exstng solder, clean the solder pads and replace them wth new solder paste. There are two types of solder paste dspensng tools commonly used n the repar area. The most basc s a hand powered mechancal dspenser. Ths tool s lke a mnature caulkng gun. The techncan attaches hs solder paste syrnge and manually squeezes the solder paste from the tube through a dspensng needle onto the pads (Fgure 6). Ths technque s sutable for applyng solder paste to large pads, paste flux durng reflow and wth practce, solder paste on ptch component pads. For mproved control of the volume of paste beng dspensed, a pneumatc dspenser s recommended. Ths type of dspenser uses ar pressure controlled by an electronc tmer to control the burst of ar that drves the solder paste from the syrnge. Ths controlled ar supply wll ncrease process control and provde a more unform solder dot sze whle reducng the techncan's hand fatgue and ncreasng solder paste placement accuracy. In addton most pneumatc dspensers ncorporate a provson for a vacuum pencl to assst n component placement. The fnal solder paste deposton method utlzes mnature stencls to carefully control the algnment and volume of the solder paste durng the repar process. These mnature stencls are fxtured over the pad array and the operator uses a mnature squeegee to apply solder paste through the stencl onto the pads. Ths s the method of choce durng the repar of fne -ptch QFPs and BGA components. The affect of fne ptch leads on repar The drve for fner ptches has affected repar by placng a stronger emphass on tools, equpment, and technques that 12 Electronc Servcng & Technology November 1995

15 ad n the placement process. Standard ptch components,.e nch lead spacng, can be placed wth relatvely smple and nexpensve hand tools. For components wth a nch ptch, placement requres greater mechancal and sometmes vsual ads. Repar systems wth mcrometer or fne lead -screw type adjustments n concert wth vson systems are an advantage when reparng fne ptch components wth nch lead spacng, and an absolute requrement wth component ptches of nches or less. In addton BGA components wth a ptch less than nches requres vson systems wth smultaneous vewng of the top sde of the PCB and bottom of the BGA. Algnment s accomplshed under hgh magnfcaton wth mcrometers for fne movement. Because of ths requrement for tght control of component replacement the trend among manufacturers of solderng/ desolderng equpment s to offer mproved vson and manpulaton of components n ther products. Trends n repar. There appear to be two trends n repar today. Frst, equpment manufacturers are offerng products that provde the user wth greater control of the process. As evdenced above, hgh -end machnes must provde fne movement and vson to address the challenges of fne ptch and BGA components. For standard component repar, lower cost systems and tools are also tryng to meet the need for mproved process control. A recent development n ths area s the OK Industres FCR-2000 repar system n whch the concept of a basc hot ar tool has been enhanced to ncorporate focused heatng, heater cycle control, component lft-off wth automatc vacuum and "hands -free" operaton wth handpece fxturng. Another emergng trend n repar s the compound or mult -functon repar system. Especally wth hand tools, at least two companes, Pace and OK Industres, have ntroduced repar statons that provde smultaneous operaton of a varety of handpeces. These systems combne the equpment requred for both SMT and through -hole assembles. Tool selecton The key to selectng equpment for your repar faclty s to dentfy the components you need to repar today. Talk to the manufacturers you have servce contracts wth to dentfy the components they wll be usng n ther future products, then select a repar system that wll grow wth your needs. Contact the solderng equpment manufacturers for catalogs, tranng manuals and vdeo tapes. Get the equpment nhouse for evaluaton on the boards you need to repar, not a dummy board. Accept any tranng that the manufacturers wll provde on ther equpment and make an nformed decson. t, of t Hghlght ths opportunty to enrch your sklls at the 1996 Natonal Professonal Servce Conventon (formerly Natonal Professonal Electroncs Conventon), Aug n St Lous, Mssour. Programs wll nclude: *Hands-on Techncal Tranng Certfcaton Management Semnars *Industry Trade Show Regster and pay by January 31 to SAVE UP TO $130 PER PERSON. For a regstraton form or more nformaton, rush the followng to NESDA: Name Busness Address Cty Zp Phone State Natonal Electroncs Servce NESDA Dealers Assocaton, Inc W. Berry St. Ft. Worth, TX (817) L Hgh -Qualty Desolderng Only $ Zr XYTRONIC 455 Reservaton Road, Ste H Marna, CA (408) voce (408) fax NIGH -TECH DESOLDERING IeervsfcnAlefoprarhgrePcreessonal Self -Contaned Vacuum Pump The Ideal Tool for Low Volume Through -Hole Desolderng No Statons, Compressed Ar, or Vacuum Lnes equred Handy 60 Watt Power *Varable Temperature Adjust Call the Prce Leaders! HOT WAND For a Dstrbutor Near You! crcle (67) on Reply Card November 1995 Electronc Servcng & Technology 13

16 SAW flters Whatever happened to f transformers By Steve Babbert n the trend toward mnaturzaton, engneers have found numerous ways to conserve crcut board space. Sometmes components were just made smaller, and sometmes a number of components were formed nto a "hybrd" devce or module. IC technology has enabled us to fabrcate hundreds or thousands of devces nto a sngle "chp." In these cases, the theory of operaton hasn't changed. Occasonally, however, a new devce wll be developed that wll take the place of one or more components by utlzng a totally dfferent concept. The SAW flter The SAW (surface acoustc wave) flter s one devce that employs an entrely new technologcal concept when t comes Babbert s an ndependent consumer electroncs servcng techncan. to provdng flterng. A sngle SAW flter can elmnate the need for most of the nterstage couplng transformers and traps used n vdeo f (ntermedate frequency) strps. These transformers and traps are the components that were used for sgnal couplng and waveshapng. Besdes takng up space, these components had other nherent problems. Not only dd they requre adjustment durng manufacturng, but they sometmes needed addtonal adjustment durng the lfe of the set. Ths need for adjustment could arse when components n the f secton were replaced, or drfted n value because of age or heat. The dstrbuted capactance of the crcut surroundng the nductve transformers and traps plays a role n determnng ther tuned resonant frequency. Any change n capactance wll requre a change n nductance n order to mantan ths frequency. The adjustment or algnment procedure could be a tedous and tme consumng process requrng servce lterature, sweep and marker generators, osclloscope, etc. Moreover, components n the f crcuts were known to fal because of open wndngs. Then there's the "human error" factor whch must be taken nto account. Screws are made for turnng, and some humans just can't resst turnng screws. Most older techs have had to deal wth recevers that were grossly msalgned by someone's brother-n-law who was attemptng to brng a weak staton to crystal clarty. Hs attempt to compensate for a recepton problem by "tweakng the f cans" often led to the customer's complant of snow on all channels. In these cases, t wasn't uncommon to fnd broken ferrte slugs. Ths breakage was usually caused by usng mproper algnment tools MHZ COLOR SUBCARRIER 45.75MHZ PICTURE CARRIER w % AMPLITUDE 39.75MHZ ADJACENT CHANNEL PICTURE CARRIER 41.25MHZ SOUND CARRIER FREQUENCY 47.25MHZ ADJACENT CHANNEL SOUND CARRIER Fgure 1. The f response curve for a typcal color televson (NTSC system). 14 Electronc Servcng & Technology November 1995

17 INPUT OUTPUT PIEZOELECTRIC SUBSTRATE A INPUT TRANSDUCER SURFACE ACOUSTIC WAVES H OUTPUT TRANSDUCER Fgure 2. The basc waveshape for the TV f response curve was obtaned by "stagger" tunng two or more stages. B CROSS SECTIONAL VIEW Fgure 3. A. A smplfed model of a SAW flter. B. A cross sectonal vew of a workng flter. The f response curve The //response curve for a typcal color TV recever s shown n Fgure 1. It has a relatvely flat top wth steeply slopng skrts. The color f subcarrer frequency of 42.17MHz and the vdeo f carrer fre- quency of 45.75MHz are at ponts that are 50% of the maxmum ampltude on opposte sdes of the curve. The upper adjacent channel pcture carrer of 39.75MHz and the lower adjacent channel sound carrer of 47.25MHz are at zero ampltude. The n -channel sound carrer of 41.25MHz s reduced to avod 920KHz beat wth the color subcarrer, but not elmnated, as t s needed by the sound secton. The shape of ths waveform s crtcal for accurate vdeo, chroma and sound reproducton. DTC COMPUTER SERVICE \II/ MINI \IN NO NMI Mr TV TUNERS/MAINBOARDS *A +CERTIFIED *SYSTEM BOARDS *MONITORS *PRINTERS *TERMINALS Corporate Headquarters 5233 Hwy 37 South Bloomngton,IN * Caft TatujI 4941 Allson St #11 Arvada, CO * OVER 40 MAJOR BRANDS IN STOCK MOST PRICED AT $gr *1 YEAR WARRANTY * 24 HOUR TURNAROUND SAVINGS UP TO 60% 110 Mopac Road Longvew, TX Crcle (59) on Reply Card *ZENITH MAINBOARDS * RCA CHASSIS THRU CTC 187 * PHILIP PROJECTION BOARDS...AND MORE! flutubag6 Stork! Parkway Loop, Ste D Tustn, CA November 19S5 Electronc Servcng & Technology 15

18 Express Cxpress Parts Express s proud to announce that we now stock the NTE lne of replacement semconductors. NTE has been supplyng the electroncs ndustry wth top notch replacement parts for over 15 years. All NTE products meet or exceed ndustry specfcatons and offer an exclusve 2 year manufacturer warranty. We also offer a complete lne of parts for the servce repar ndustry. Test equpment, loudspeakers, vdeo and audo heads, magnetrons, dler assembles, gftbelts, tools, solderng equpment, just to name some of the 12,000 tems we stock. Ask about our new dealer program for resellers. Call toll free for a copy of our FREE 212 page catalog. Source Code: ESM CALL TOLL FREE Parts Express 340 E Frst St. Dayton. Oho Phone Fax: Crcle (60) on Reply Card ISCET VCR Cross Reference VCR Model Number Cross Reference and VCR Parts Cross Reference 0 5th Edton. Contans both model- and parts- number cross references for more than 1,700 models and almost 5,000 parts. $29.95 Plus shppng $ One 3'/z" dsk, or 0 Two 5 Vs" dscs. Verson 6.0, for IBM PC AT/XT or compatbles. Requres hard drve and DOS 2.1 or greater $69.95 Plus shppng $ Specal Combo Offer. Your choce of dscs, plus 5th Edton VCR Cross Reference. $95.00 Plus shppng $3.00 A "WEIGHTED" FINGER ARRAY Fgure 4. A smplfed "weghted" fnger array. Snce LC resonant crcuts peak at a sngle frequency, a method known as "stagger tunng" was often used to obtan the basc response curve. In ths method, ndvdual stages were tuned to dfferent frequences wthn the passband. The result was an overall response wder than that whch could be obtaned wth a sngle stage (Fgure 2). LC traps were employed and tuned as needed to notch out unwanted frequences. How SAW flters work SAW flters functon by convertng an electrcal sgnal nto a mechancal vbraton or "acoustc wave." After ths wave passes along the surface of the crystal n whch t s nduced, t s converted back nto an electrcal sgnal. Essentally, the SAW flter s a double transducer, snce the energy converson takes place twce. The energy converson s made possble by the pezoelectrc effect. If a voltage s appled across a substance exhbtng the pezoelectrc effect, the substance wll twst or bend. Conversely, f ths substance s twsted or bent, t wll produce a voltage. Ths effect has been wdely used n crystal oscllators, ceramc phono pckups and n cgarette lghters to generate an electrc spark to gnte the lghter fuel. Some materals used for the SAW flter substrate are slcon oxde, thn flm znc oxde, lthum tantalate, lthum nobate, bsmuth, germanum oxde and quartz. Ths materal s formed nto a slab and ts surface s hghly polshed. Next, metallc electrode arrays are formed on ts surface usng a photolthographc process (Fgure 3). Sgnal appled When an ac sgnal s appled across the nput secton of the crystal va the two halves of the nput array, the crystal's surface vbrates at the sgnal frequency. These vbratons create waves whch traverse the surface of the crystal to the output secton (Fgure 3b). The correspondng voltage varatons on the surface are pcked up by the output array. Durng ths process, specfc bandwdth and frequency characterstcs have been establshed. SAW flters are talored to partcular applcatons by selectng specfc geometrc structures for the nput and output arrays. Low frequency components of a sgnal are transmtted and receved by wde spread fngers, whle closely -spaced fngers favor hgh -frequency components. Devces can be made to work even n the ggahertz range. A large number of unform fngers restrcts bandwdth. A unform array wth Allow 4-5 weeks delvery when usng personal checks or VISA and MasterCard. Money orders and cashers checks processed mmedately. Amount VISALJ MasterCardU Card No. Exp. Name Busness Address Cty State Zp Phone Member U ISCET O NESDA Texas resdents multply dollar value x 71/4% for taxes. Foregn shpments please add nternartonal postage. Send ISCET W. Berry St., Ft. Worth TX Fgure 5. A smplfed vew of an actual devce desgned to talor the f response. 16 Electronc Servcng & Technology November 1995

19 only a few fngers wll have a broad frequency response. For a specfc response wth sharp cutoffs, "ampltude weghted" fnger arrays are used (Fgure 4). In ampltude weghtng, the amount of overlap s vared throughout the array. Problems n SAW flters It s possble for reflectons to pass from the output to the nput and then back. These waves would then have three tmes the delay of the drect wave. Ths can cause ghosts n the pcture, smlar to those caused by multpath antenna recepton. Splt fnger arrays double the ncdent wave frequency, pushng t outsde of the passband. Reflectons from the bottom to the top of the crystal, known as bulk wave reflectons, sometmes occur. These can be elmnated by placng a mult -strap coupler between the nput and the output. Mult -strap couplers consst of a number of "dummy" fngers whch are formed wth the nput and output arrays. Other forms of dstorton can be dealt wth by modfyng the array confguratons. The many desgns are too numerous to be ncluded n ths dscusson. Wave propagaton In SAW flters, the acoustc wave travels slowly (about 10-5 tmes that of an electromagnetc wave) much as sound - waves do, yet they mantan the frequency of the source. Ths propagaton delay makes these devces useful as delay lnes. Older televson recevers used long nductve delay lnes to delay the vdeo sgnal by about Ths was requred to keep t n phase wth the chroma sgnal whch encountered the same delay n the chroma processng crcutry. A smplfed model A smplfed model of a SAW flter provdng complete f shapng for a Zenth color TV s shown n Fgure 5. Ths devce conssts of nput and output nterdgtal arrays whch are offset and separated by a mult -strap coupler. The substrate s made of lthum nobate. The nput array s weghted for selectvty. It has a very low sgnal loss at 44MHz (the center of the f passband). It provdes the requred MHz sound carrer attenuaton and traps the unwanted 39.75MHz and 47.25MHz carrers. Frequences outsde the passband are sharply attenuated. The output array conssts of a few unform fngers for a broadband response. The substrate s mounted on the nsde bottom of a ceramc package, the bottom of whch has a conductve coatng. Ths acts as a sheld when grounded. The devce s hermetcally sealed wth epoxy. Newer devces are mounted n dme -szed metal cans that resemble button cell batteres. The symbol for the SAW flter s shown n Fgure 6. Some earler schematcs show them as fve -pn ICs. A devce n crcut The f output from the tuner s termnated n an LR network whch provdes the correct match to the SAW flter (Fgure 7). The double -ended output of the flter s appled to pns 2 and 14 of a three - stage f amp IC. Drect couplng s used between the three stages snce the proper waveform has already been establshed. hllm=11111\sy SAW FILTER CERAMIC FILTER CRYSTAL IC Fgure 6. Commonly used symbols for a SAW flter, a ceramc flter (the smaller relatve of the SAW flter), and a standard crystal (notce the resemblance to the symbols for the SAW and ceramc flters). Contrast ths wth a typcal desgn usng conventonal LC crcuts (Fgure 8). A smaller relatve of the SAW flter s the ceramc flter. The symbol for ths devce s shown n Fgure 6. Ths three -termnal devce uses the same prncple, but VHF IF IN (FROM TUNER) RD STAGE IF AMP 0 IF OUTPUT TO DETECTOR Fgure 7. The f output from the tuner s termnated n an LR network whch provdes the correct match to the SAW flter. The double-ended output of the flter s appled to pns 2 and 14 of a three -stage f amp IC. Drect couplng s used between the three stages snce the proper waveform has already been establshed. November 1995 Electronc Servcng & Technology 19

20 Fgure 8. Contrast ths typcal desgn usng conventonal LC crcuts wth the desgn of Fgure 7 whch uses a SAW flter. has a much narrower bandpass characterstc. For ths reason, the desgn s smpler and the elaborate nput and output arrays are omtted. These are used almost exclusvely for nterstage couplng n fm recevers and other audo communcatons equpment. The center frequency s usually stamped on the case. They resemble ceramc capactors except that they are rectangular and have flat leads. Summary The SAW flter has smplfed the f secton of TV sets, and elmnated much of the algnment that was assocated wth the early televson recever. Some older techncans who took prde n ther mastery of the art of algnment may well wonder what wll be done away wth next. Remember though, not all breakthroughs and mprovements result n decreased complexty: just look at any swtched - mode power supply. At least for the tme beng t s safe to assume that as one challenge passes a new one wll emerge. To Order Back Issues SECISOUIC Only $3.50 Per Issue When orderng back ssues nclude the followng nformaton: Name, address, cty, state & zp. Please make a lst of the ssues you're requestng. When payng by credt card send the number along wth the expraton date. Check, Money Order, Mastercard, VISA, Dscover and AMEX accepted. Complete your collecton today or Fax Electronc Servcng & Technology 76 North Broadway Hcksvlle, NY Electronc Servcng & Technology November 1995

21 Pck and place and holdng fxtures By The ES&T Staff There was a tme when most components n consumer electroncs products were as bg as your fnger, and just plugged n. Even f the techncan was unlucky and the problem was a bad resstor, a fx usually meant bendng the leads to ft, and solderng the replacement nto the crcut usng an 100W solderng tool. Now, thngs have changed dramatcally. Most components are so tny that they border on beng nvsble. Even mutleaded ICs are so tny that a healthy sneeze can blow them across the room. And because they're multleaded t's mportant to get the ICs properly lned up on the PC board tracer. But that brngs up yet another problem concernng these tny components and the PC boards they're mounted on. For those of us who have only two hands, t's hard to hold the PC board to keep t from movng whle you're tryng to place the component on the board and solder t. Pck and place tools Fortunately for the harred and overworked techncan, there are tools that allow hm to pck up the smallest component, transfer t to the PC board, and place t n precsely the correct poston. One example of such a pck and place devce conssts of a bent metal or plastc tube wth a hole n t. One end of the tube ends n a tny sucton -cup -type devce. The other end of the tube connects to a vacuum source. To use ths devce, the techncan places the sucton -cup end of the tube on the component that s to be pcked up, leavng the hole n the tube uncovered. As long as the hole n the tube s open, the vacuum can pull n ar at that pont rather than at the sucton -cup end. Once the sucton -cup end of the tube s n the rght locaton the techncan covers the hole wth a fnger. Now a vacuum s created and the component can be neatly lfted. Now usng the tube, or wand, the techncan can transfer the tny component to ts precse locaton and orentaton en the PC board. Once t's n poston he merely has to remove hs fnger from the hole releasng the vacuum and the com- A crcut board holder such as ths allows the techncan to place the PC board at a convenent angle for solderngdesolderng. (Photo courtesy Pan amss) ponent stays n poston on the board untl t s soldered n place. At least one manufacturer offers a smlar devce that doesn't requre an outsde source of vacuum. Wth ths manual devce, the user merely has to place the sucton -cup end of the devce or the component to be lfted then manpulate a button or lever, whch creates the vacuum. Then, once he has placed the component where t needs to go he releases the vacuum, and then proceeds wth solderng. Holdng the PC board n place But, pckng up the component and placng t on the PC Board s only part of the problem. How do you hold the PC board at a convenent angle and keep t from movng? And, how do you keep from damagng components on the board, or some of those delcate traces? In many cases that queston s answered for the techncan. The PC board remans wthn the product beng servced and he gets to the locaton where the component belongs as best he can. But then there are cases n whch the PC board s completely removed from the unt n order to desolder the defectve component and solder n the replacement. In such cases the techncan may have to resort to proppng the board up on a couple of peces of wood, or leanng t aganst somethng to set t at the desred angle. Of course when the replacement of components s done ths way t's rarely possble to get the PC nto just the poston you want. Even worse s when the board slps just as you apply the solderng ron to the connecton. Holdng fxtures Fortunately, there are devces that make all that messng around unnecessary, and allow the techncan to put the PC board exactly where he wants t, and at exactly the rght angle. Ths way, there's no chance that any components or tracer wll be damaged durng servcng. These holdng fxtures are avalable n a varety of szes and styles, from a number of manufacturers and dstrbutors. Wth these the techncan smply clamps the PC board nto the fxture, places t just where he wants t, adjusts t to the desred angle, and goes to work. November 1995 Electronc Servcng & Technology 21

22 The TV color sgnal By Lamar Rtche The July ssue featured an artcle "Televson theory," whch descrbed the basc theory of monochrome televson. Ths contnuaton of that artcle descrbes how color was added to the sgnal whle allowng monochrome TV recevers to receve the same sgnal wthout color. A n m AL V I II chroma sgnal 4n-r concentraton = monocarorn+ sgnal enerql concentraton The NTSC color system Many systems were expermented wth for the transmsson of color TV sgnals before the present NTSC color system was adopted. The man obstacle to the development of the color vdeo system was the need for compatblty. The color vdeo sgnal had to be constructed n such a way that the monochrome vdeo would be essentally unchanged. Exstng recevers must be able to reproduce the sgnal as a black and whte mage and the sgnal must occupy nearly the same bandwdth that the monochrome sgnal dd. These are severe lmtatons whch produced several compromses n the color system. There are, of course, an nfnte number of colors. What we call color s nothng more than the dfferent frequences of lght that we can see. The lowest vsble lght frequency that we can see s the frequency correspondng to the color red and the hghest s that of the color volet. There s a large number of frequences between these extremes. Foolng the eye We can produce the lluson of havng all colors by usng varyng mxtures of the three prmary colors of lght-red, green and blue. Transmsson of color televson, therefore, requres that three vdeo sgnals be recovered at the recever; the red, green and blue vdeo sgnals. These are referred to as the R, G and B vdeo sgnals. The monochrome sgnal contanng only the relatve brghtness nformaton s called the Y sgnal. The dervaton of the color vdeo sgnal parameters s exceedngly complex. As an example, whte lght s actually a mxture of all colors, and thus can be consdered as a mxture of all three prmary Rtche s an electroncs nstructor at Kentucky Tech, Hazard Campus H 15H 2H 2.5H 3H 3.5H 4H 4.5H 5H BH 6.5H 7H 7 5H IH IH horzontal ran frequent" Az Fgure 1. Most of the frequency spectrum used by the monochrome vdeo s clustered n "packets" that are harmoncs of the horzontal scannng frequency: 15.75Khz. The color sgnal s placed n between these areas, n the frequences that are lttle used by the monochrome vdeo n a process called nterleavng. colors. To appear whte, however, the relatve amounts of the colors must be exact. The color mx s also mportant for any objects that are gray, as gray could be consdered to be a "darker whte" color. Note that the monochrome TV sgnal can reproduce black, grays and whte. To appear a neutral gray or whte color, the same as the monochrome mage, the color sgnals must have ths proporton: Y = 0.3R G B If the colors are n the proporton of 30% red, 59% green and 11% blue, the mage should appear as a gray to whte shade to us. To do ths electroncally, any sgnal that we are usng to convey color must "dsappear" when ths rato exsts. COLOR BURST (180 ) YELLOW 0 RED (104 ). GREEN (241 ) Stll too many sgnals for TV transmsson Thus far, we have managed to reduce the number of sgnals needed to convey color, and sgnals conveyng the prmary colors to three. These sgnals are stll too many, however. In order to further reduce the nformaton that needs to be transmtted, TV engneers developed a system that has been used n trgonometry for a long tme: "vectors." A vector s a quantty wth both a magntude and a drecton. If these vectors are assgned an orgn at the ntersecton of two axes (the X and Y axes), an nfnte number of locatons and drectons can be assgned by usng only two rectangular R -Y MAGENTA CYAN PHASE ANGLES OF THE VARIOUS COMPONENTS OF THE COLOR SIGNAL B -Y BLUE (347 ) Fgure 2. The two sdeband sgnals are created by subtractng the lumnance value from both the red and blue sgnals. These are called the R -Y and B -Y sgnals. These are used n a quadrature modulator and are essentally the rectangular coordnates that produce the varous phase angles for the ndvdual colors. 22 Electronc Servcng & Technology November 1995

23 coordnates, provdng both postve and negatve numbers can be used. Ths s the scheme that was used to develop the color sgnal. Usng ths scheme, all of the color nformaton can be transmtted usng only two sgnals. These sgnals can represent rectangular coordnates wth the colors assgned as vectors havng varous phase angles. Furthermore, these two sgnals can be assgned as ndependent sdebands of a sngle am sgnal. It s possble to produce a color sgnal, then, as a sngle am sgnal wth two ndependent sdebands. It was necessary to place ths modulated sgnal on the exstng baseband vdeo sgnal. Ths entre sgnal s then used to modulate a carrer n the vdeo transmtter, so nstead of beng called a carrer, t s actually called a subcarrer. COMPLEMENTARY COLORS horz. blankng horz. sync. PRIMARY COLORS J color sgnal -rdes or ----lumnance sgnal color burst The color subcarrer The color nformaton s placed n the exstng monochrome vdeo as a color subcarrer or chromnance subcarrer, to use ts accurate name. I must pont out now that the subcarrer s not actually transmtted. It s suppressed after the sub - carrer modulaton process that produces the two sdebands, n order to reduce nterference wth the monochrome vdeo. Ths means that to demodulate the color sgnal, ths color subcarrer must be renserted by the televson recever crcuts. The recever uses a crystal oscllator for ths purpose, but even a crystal oscllator s not stable enough to free -run at the exact frequency needed. To "lock" n the crystal oscllator, eght to ten cycles of the orgnal color subcarrer frequency are placed on the "back porch," or tralng edge of the horzontal blankng to be used as reference pulses to whch the color oscllator n the recever can lock. These wll be easy to gate through to the oscllator by usng a delayed horzontal sync sgnal n the recever. Color frequences Because the color sgnal must use the exstng bandwdth allowed for the monochrome sgnal, and therefore must be placed n the same frequences, t wll appear vsble on the TV screen. Note that I am sayng the color sgnal wll be vsble. The colors that are the result of demodulatng ths sgnal wll also be vsble, of course. We want to see the colors. We do not want to see the color sgnal. Fgure 3. The phase of the chroma sgnal compared to the burst determnes the partcular color (hue) of an object, and the ampltude of ths sgnal determnes the saturaton (amount of color) for an object. Ths llustraton shows how the color sgnal mght appear for the ndcated televsed scene. Because the color sgnal s essentally a sne wave that vares n phase, t would appear on the screen as a seres of lght and dark colored pxels as the sne wave alternated between ts postve and negatve peaks. The trck here s to place these pxels n areas that are not used much for the monochrome mage so that they wll nterfere as lttle as possble wth t. Because the pcture nformaton s scanned one horzontal lne at a tme, and the spacng between lnes s very small, most of the vdeo nformaton s repettve at the horzontal scan rate. Ths means that most of the frequency spectrum used by the monochrome vdeo s clustered n "packets" that are harmoncs of the horzontal scannng frequency: 15.75Khz. The color sgnal s placed n between these areas, n the frequences used by the monochrome vdeo n a process called nterleavng (Fgure 1). Interleavng For nterleavng to take place, the color subcarrer frequency must be an odd multple of one-half the horzontal scan rate. There are other thngs to consder, however, before ths frequency s chosen. The frequency of the color subcarrer should be as hgh as possble so that the resultng nterference pattern that t creates on the screen wll be as small and unnotceable as possble. We have up to about 4MHz as the upper end of the vdeo spectrum. It should be obvous at ths pont that the chroma sgnal cannot produce as much detal as the monochrome sgnal, whch has the full 4MHz. Although the eye s not as senstve to detal for colors, the color subcarrer must be placed far enough down from the upper frequency lmt to allow a reasonable bandwdth for t-at least 500KHz. Ths would put t's frequency somewhere n the vcnty of 3.5MHz. Avodng audo nterference Another problem arses n that the frequency of ths sgnal s very close to the sound carrer frequency of the transmtter. Ths transmtter s operatng at a frequency that s 4.5MHz above the vdeo carrer frequency and the color sgnal can "beat" wth t to produce dfferent frequences that are 1MHz or below, and would produce an objectonable nterference pattern on the screen. Ths s one reason why the chromnance (color) subcarrer was suppressed and only the sde - bands of the chroma sgnal used. To mnmze deteroraton of the pcture qualty that mght be caused by the heterodynng of the sound carrer and November 1995 Electronc Servcng & Technology 23 quadrature. The I sgnal s placed at +123 degrees and the Q sgnal at +33 degrees, hence they are stll 90 degrees apart as were the R -Y and B -Y sgnals and can be used to derve any of the other colors by vector addton. The dfference s that the I sgnal can produce reddsh -orange and blue-green colors by tself (look at the +1 and -I vectors on the prevous dagram). These are the colors for whch the eye s most senstve to detal. For these colors, the Q sgnal drops out, snce t s not needed anyway, and the I sgnal uses the entre color sgnal bandwdth tself. It was decded to allow MHz of bandwdth for the I sgnal. Ths gves approxmately three tmes the color detal that R -Y, B -Y encodng has. Consderng the upper and lower sdebands of the I sgnal, ths means that t would need frequences of 3.58MHz - 1.5MHz. to 3.58MHz + 1.5MHz. The lower sdeband of the I sgnal s used as s, but the upper sdeband s fltered and lmted to a frequency around 4.2MHz. As far as the recever and the vdeo sgnal are concerned, the results of I - Q, and IC's have reduced the sze and cost of crcutry to the pont where consumer vdeo equpment (camcorders) now use the better system. A modern S -VHS cam - Internatonal Wnter Consumer Electroncs Show January 5-8, 1996 Las Vegas. NV Moble Electroncs Show Aprl 19-21, 1996 Orlando, FL CES Orlando '96-The Dgtal Destnaton May 23-25, 1996 Orlando, FL ES&T Calendar occurs n a system, some knowledge of the prncples of operaton of the system always enhances the ablty of the servce techncan to determne the cause. CES Habtech May 23-25, 1996 Orlando, FL CES Specalty Audo and Home Theater Show May 23-25, 1996 Orlando, FL November 1995 Electronc Servcng & Technology 25

24 I 100 E 90 E 80 E U 50 N 40 I 30 T 20 S \ rn +77 m 0 z m m z 33 r m NTSC COLOR BAR PATTERN Fgure 4. For 100% saturated colors (for example, as deep a blue that you can get) the ampltude of the sgnals would be hgher. The ampltudes standardzed for 100% saturated colors are shown here. color sgnals, ths beat dfference fre- I L 20 The color subcarrer frequency color. It s the ampltude of the color sgnal that determnes the saturaton of the color. It s the nstantaneous phase of the color sgnal, compared to the burst, that determnes the hue of the color. Refer to Fgure 2. The two sdeband sgnals are created by subtractng the lumnance value from both the red and blue sgnals. These are called the R -Y and B -Y sgnals. These are used n a quadrature modulator (whch creates sdebands 90 degrees apart) and are essentally the rectangular coordnates that produce the varous phase angles for the ndvdual colors. Note that the phase of the burst s not 0 degrees, but s placed at 180 degrees. Ths s to prevent nterference wth the B- Y sgnal. The burst s restored to 0 degrees n the recever by a smple process of phase reversal. After modulaton, then, the composte color vdeo sgnal conssts of all the parts that exsted n the monochrome sgnal (called the Y sgnal), wth mnor changes to the sync frequences, plus a chroma sgnal (referred to as the C sgnal) that rdes on the lumnance. A color burst or color sync sgnal s used as a reference to ndcate the 0 degree axs. Vacuum tubes revsted By Arthur Flavell Snce the ntroducton of transstors and ntegrated crcutry, vacuum tube applcatons have declned dramatcally. Whle obsolete n many current applcatons, vacuum tube technology has not dsappeared entrely. Some types of equpment, such as rado transmtters and muscal nstrument amplfers, stll use tubes. The cathode ray tube dsplays n televsons and computer montors are vacuum tubes, whle magnetrons are vacuum tubes that are used n radar and mcrowave ovens. A growng nterest n restoraton of vntage equpment may present an opportunty to work on Uncle Fred's old tube -type table rado. The well-rounded techncan should be famlar wth the bascs of vacuum tube operaton as well as the technques and hazards of troubleshootng tube crcuts. Basc vacuum tube theory In smplest terms, a vacuum tube s a devce that controls a flow of electrons. It s used n a varety of electronc crcuts such as rectfers, amplfers, oscllators and swtches. The elements of a vacuum tube are enclosed n an evacuated envelope made of glass, ceramc or metal. Each vacuum tube contans elements Flavell s owner of an ndependent consumer electroncs servce center n Alaska. for carryng electrcal current nto and out of the devce. The element connected to the lower (less postve) voltage pont s called the cathode. The element connected to the hgher (more postve) pont s called the anode or plate. The cathode s coated wth a materal whch enhances the generaton of free electrons. The release of electrons s enhanced by heatng the cathode materal wth a flament or heater element. When the flaments are energzed, a "cloud" of electrons s produced around the cathode by a process known as thermonc emsson. Internal current flow s n the form of an electron stream from the cathode, through the vacuum, to the plate. The postve potental of the plate attracts electrons from the cathode. When the tube s connected n a complete crcut, current wll flow. Electron current wll not flow n the reverse drecton (from anode to cathode). Vacuum tube types A two -element vacuum tube s known as a dode and performs the same functons as ts sold-state cousn. Fgure 1 shows the schematc symbol for a dode. Wth a dode, only two operatng condtons exst. If the plate s postve wth respect to the cathode, current wll flow through the tube. If the plate s negatve wth respect to the cathode, no current wll flow. The ampltude of current flow s a functon of the appled voltage and the total resstance n the crcut. For more complex crcut applcatons, current flow through the tube must be vared between the full off and full on condtons. Ths s accomplshed by addng a control element to the basc dode confguraton called a grd. The control grd s located between the cathode and the anode. Ths three element tube s known as a trode. Fgure 2 shows the schematc symbol for a trode. In most crcuts, the control grd s negatve wth respect to the cathode and does not carry current. Ths provdes a repellng effect to the electrons released from the cathode, reducng current flow through the tube. Relatvely small voltage varatons on the control grd produce large changes n plate current and voltage. The varatons n plate voltage are amplfed versons of the control grd voltage and are 180 out of phase wth the voltage at the nput. Some crcuts, such as RF power amplfers, allow the grd to go postve for a porton of the nput waveform, and grd current wll flow. Whle the trode s useful n many applcatons, t does have some lmtatons. Performance n the RF regon suffers from nter -electrode capactance PLATE CATHODE HEATER Fgure 1. The schematc symbol for a dode. Fgure 2. The schematc symbol for a hode. 26 Electronc Servcng & Technology November 1995

25 SUPPRESSOR GRID SCREEN GRID CONTROL GRID SCREEN GRID Tetrode Pentode Fgure 3. The schematc symbols for tetrode and pentode tubes. whch causes nternal feedback and self - oscllaton. To overcome these lmtatons, tubes were developed wth addtonal elements. Examples of these are the tetrode and pentode tubes shown schematcally n Fgure 3. Vacuum tube numberng There are a number of electrcal and physcal characterstcs of vacuum tubes that apply to a varety of types. Here are a few practcal topcs that may be useful. Vacuum tubes used n consumer products are often dentfed wth an alpha -numerc desgnaton. Typcally, t s a number -letter -number combnaton, such as 5U4, 6GH8, 12AU7, etc. For tubes wth ths type of dentfer, the number at the begnnng of the desgnator ndcates the flament voltage. In the prevous exam - pes, the flament voltages are 5V, 6V and 12V respectvely. Ths system does not apply to ndustral or mltary tubes wth four -dgt desgnatons. Tube envelopes are made of glass, metal or ceramc materals, wth glass beng the most common. The tube type s prnted on the outsde of the envelope. Identfers on older tubes may be fant or badly faded. When the tube s cold, wpe t gen- Improve Your Form. 3/5 Part 7z-.a. res.- A contnuous feed form used for customer COD servce. parts/ accessory sales recepts, and warranty btng: Includes techncan hard copy and set tag. Avalable n 3 -part (N3CS) and 5 -part (N5CS) format. 5 Part A contnuous feed 5 -part D. fy.onsw ' E7 *MY r.."'""''f"-"''''meoo=emmmmme =M4781- U O 0 0 U U 0 (N5CN) form for warranty bllng that does not nclude a set tag. Dscounts Carbonless NESDA Forms are avalable to NESDA members at addtonal savngs. For prcng nformaton and samples, contact Moore Busness Products at the number below. The NESDA Form Moore Busness Products (800) Just j 89-::: _ phone and an Andrews lne card.:. s_ :..., -- NV. v 1...and you have cover dfferent parts n stock. Shpped the same day!* AIWA SONY EMERSON HITACHI JVC RCA* PANASONIC OPTONICA SCOTT PROSCAN* QUASAR TECHNICS GE* ZENITH SHARP (*Premerl TOSHIBA Over a 90% Fll Rate Free or Dscounted No mnmum orders freght program Backorder reports wth Fast. Effcent ETA's maled bweekly Research ae No handlng charges Factory Authorzed Ipprs toordery recetwed by 2.30 PST Phone FAX P.O. l Sant.' ( h t.. C )14 andrews Intrc.: S( N1 electroncs I \ Stockng the Largest Inventory of O.E.M. Parts, Accessores, and Servce Lterature n the Country Crcle (52) on Reply Card November 1995 Electronc Servcng & Technology 27

26 Fgure 4. Pn arrangements for 7 -pn, 9 -pn mnature types and octal bases. tly wth a damp cloth to remove any dust or drt. Then breathe on the envelope as f you were cleanng a par of eye glasses. In many cases, ths makes the markngs readable. A couple of publcatons are helpful when workng on tube crcuts. A tube manual contans techncal nformaton for each tube type, ncludng normal and maxmum operatng voltages and currents, characterstc operatng curves, element pn arrangements, and other data. A tube substtuton manual s also handy when exact replacements are not avalable. Gassy tubes To functon properly, tubes must mantan a hgh degree of vacuum nsde the envelope. Tubes may accumulate gas, ether from molecules released from the tube elements or through leaks n the envelope seal. Such tubes are sad to be "gassy" or "soft." One ndcaton of a gassy tube may be a blush glow nsde the tube when operatng. Another ndcator s the condton of the getter materal. The getter s a small rng nsde the envelope whch s loaded wth a gunpowder -lke materal. When the envelope s evacuated durng manufacture, the getter s fred to help drve out gas, creatng a shny slver depost n the nteror surface. When the tube becomes gassy, the getter materal turns a dull brown and may be surrounded by a graysh flm. Pn arrangements Indvdual elements n vacuum tubes are connected to metal pns whch penetrate the envelope. Dfferent tubes have dfferent numbers of pns. The 7- and 9 - pn mnature types and octal bases are the most common. Fgure 4 llustrates pn arrangements for these tubes. Schematc dagrams or a tube manual wll llustrate whch tube element s connected to each pn. Some tubes have connectons at postons other than the base. Tubes used n hgh -power crcuts, such as RF amplfers, sweep tubes n televsons and some rectfers have plate connectons at a cap on top of the tube. Crcut connecton s made wth a frcton -ft socket. Corroson can make these connectors dffcult to remove. Care should be used to prevent the cap from breakng off or the tube envelope from crackng. Troubleshootng vacuum tube crcuts The functon of vacuum tube crcuts s smlar to the functon of sold state crcuts. However, there are some mportant dfferences. Vacuum tube crcuts operate wth potentally lethal voltages and currents! The plate voltage supply or B+ voltage may run from several hundred to several thousand volts. A good practce to follow whle takng lve crcut measurements s to keep one hand tucked n your hp pocket to avod the possblty of a shock across your chest. In many cases, equpment falure s the result of tube falure. It's a good dea to check f the tube flaments are lt. Wth glass envelope tubes, a red glow should be vsble. Wth metal or ceramc tubes, resstance checks out of crcut wll pnpont an open flament. In some older equpment, tubes are selected so that the ndvdual flament voltages add up to 120V. Ths allows the flaments to be connected n seres and operated drectly across the ac lne. Lke a strng of Chrstmas lghts, f one unt fals, the whole strng goes out. Voltage checks along the seres strng wll reveal whch flament s the culprt. Newer equpment uses 6V or 12V flaments fed by a low voltage secondary of the power transformer. In ths case, the flaments are connected n parallel and the falure of one wll not affect the operaton of other tubes. To smplfy schematc dagrams n some cases, the flaments of all tubes may be grouped together rather than shown ndvdually. A tube tester wll gve a quck go/nogo ndcaton and can reveal nternal shorts. If a tester s not avalable, conventonal sgnal tracng and sgnal njecton technques may be used (agan, remember that tube crcuts have hgh voltages present). A dc blockng capactor should be used on sgnal generator leads to prevent any overloadng of the generator output. Problems n other areas of tube crcuts If the tubes check out okay, look for the problem n other areas. The power supply s hgh on the lst of trouble sources. A voltage check wll reveal problems n ths area. Electrolytc capactors are common problem makers, partcularly n older equpment where they may have dred out and become leaky. Check for excessve rpple on the B+ and other dc supples. Electrolytcs can cause problems n other areas, too. Fgure 5 shows a smple vacuum tube audo amplfer. C2 s an nter - stage couplng capactor. A faulty couplng capactor can prevent or reduce sgnal transfer from one stage to the next. Many tube crcuts are self -based wth a resstor between the cathode and the ground (R2 and R4). Current flow through ths resstor creates a small postve voltage at the cathode. Wth the control grd at ground potental, a dc bas s developed, wth the control grd negatve wth respect to the cathode. To allow the cathode to operate at ground potental for the ac sgnal, an electrolytc capactor s used to bypass the cathode resstor (C3 and C4). Falure of ths capactor causes reduced stage gan by degeneratve feedback or "swampng." When the problem has been narrowed down to a specfc stage, voltage checks on the tube's elements can help solate defectve components. The B+ voltage may be suppled to the tube plate through 28 Electronc Servcng & Technology November 1995

27 Fgure 5. A smple vacuum tube audo amplfer crcut. a plate load resstor (R1) or through an nterstage transformer (T1), such as an audo output transformer. If B+ s present at the power supply but s mssng at the plate, suspect an open plate load. The EX -680 Dgtal Controlled Desolder Staton. The deal desoderng staton for senstve electronc crcuts. Features a three dgt LED readout dsplayng temperature settng and readng and operator lock out system. $4,80 COMPLETE! Contnuous vacuum s acheved through an n-house ar supply f Itered and regulated from ps and PNEU-VAC foot pedal actvatng a ventur system for an nstant vacuum force of 20-23'Hg. Ideal for mult -layer jonts of hgh thermal mass and tght lead to hold clearance. Includes pencl grp statc d sspalve handpece to protect senstve components. Meets all applcable mltary standards of EOS/ESD requrements. Tel: FAX Ar A P. E --momml Automated Producton Equpment. Corp. Corporate Offce 142 Peconc Ave., Medford, N.Y Crcle (76) on Reply Card same analyss holds true for the screen voltage supply n a tetrode or pentode - vacuum tube crcut (R5). Vacuum tubes may be the dnosaurs of the electroncs age, but they are not extnct yet. An understandng of basc theory and an awareness of the safety hazards nherent wth vacuum tube equpment can help expand your servce base and generate more profts. Computer Montor Tester Prce: $ S&H Includes battery, AC adapter, Mac adapter and 120 day warranty Fnally, a low cost way of gettng nto the montor repar busness. Test and repar computer montors wth speed and accuracy. The "Checker 12" s an easy to operate, hand held, battery, or AC operated computer color montor pattern generator. Wth ts support of CGA (15.75khz), EGA (22khz) MACII (35khz), and VGA modes 1,2,3 (31.5khz) 800X600 (35khz, I024X768 nterlaced (35khz), 1024X768 non -nterlaced & 1024X768N1 wth sync on Green (48khz), you can easly checkout a montor n all of ts' modes. Wth ts' sngle mode swtch, you know exactly what type of montor you are testng. Its' front panel color pctures show just what you should be seeng on the montor under test. You can qucldy tell f the montor s a VGA, SVGA, or a SVGA/NI. The "Checker 12" provdes varous test patterns for VGA montors. X -hatch, for sze and lnearty and convergence set-up. Whte screen, for purty and CRT burn evaluaton. Color bars and 8 step gray scale for color trackng and balance. There s also a sngle color mode that allows for sngle color channel operaton. Computer and Montor Mantenance az We also have the Checker VI, a sx port stand-alone VGA (640X480) test pattern generator. No computer requred. Just Crcle (55) on Reply Card November 1995 Erectronc Servcng & Technology 29

28 Interrupted agan! Installng adapter cards n a mcrocomputer By John A. Ross Recently, one of my employees attempted to nstall an nternal modem and a sound card nto a customer's mcrocomputer system. The system was an IBMcompatble, 486 -based mcrocomputer runnng MS-DOS verson 6.22 and Mcrosoft Wndows After an hour on the job, Joe called back to the offce and complaned that the modem would not send or receve data and that the sound card only worked part of the tme. When Ross s a techncal wrter and mcrocomputer consultant for Ft. Hays State Unversty, Hays, KS the modem dd work, the mouse would not. A job that had seemed lke a smple matter of nsertng cards nto a computer had now become a frustratng experence. The problems that Joe encountered durng the nstallaton of the modem and the sound card are farly common problems. Any tme a techncan nstalls addtonal adapters nto a mcrocomputer, those adapters requre system resources. The addtonal adaptors then compete for those resources whch other attached devces are already usng. If two adapters compete for the same resources, a devce conflct occurs. Wth that conflct, nether devce wll work. Watch those resources Mcrocomputer systems offer four basc types of resources for use by those pesky adapters. Those resources are: Interrupt Request Lnes (IRQ's) Input/Output Addresses (I/0s) Drect Memory Access Channels (DMAs) Upper Memory Blocks (UMB's). SERIAL PORT KEYBOARD SIGNALS SCP sc SERIAL CONNECTOR <0:2 LINES/ INTERRUPT ONTROLLER XDO - XD7 DMA CONTROL 1 XAO - XA9 DMA CONTROLLER SAO-SA231,,/ ADDRESS BUFFERS XAO - XA23 DECODE AND CONTROL LOGIC XDO - XD7 <DO - SD DATA BUFFERS XDO - XD7 TIMER XDO - XD7 XAO - XA26 XAO XA23 DMA REFRESH LOGIC BUS CONNECTORS PARALLEL PORT PARALLEL PORT CONN. Fgure 1.The upper left-hand corner of Fgure 1 schematcally shows the relatonshp between the nterrupt controller, the IRQ lnes, and the remander of the system. The relatonshp between DMA control and the remander of the system s shown as a schematc representaton. The DMA crcutry s shown towards the rght sde of the fgure. Durng drect memory addressng, the CPU s put nto a hold state whle the DMA controllers drve the address and control lnes. 30 Electronc Servcng & Technology November 1995

29 IRQ's Adapters communcate wth the central processng unt of the system through nterrupt request lnes. Interrupt requests are specal sgnals that stop the current operaton of the mcroprocessor. When a specfc nterrupt sgnal s receved by the CPU, the mcroprocessor nterrupts ts routne and begns a specal programmed routne. When the mcroprocessor completes ths specal program, t goes back to the pror task. Perpheral devces attached to the mcrocomputer-such as scanners, modems, prnters, and SCSI adapters-utlze nterrupt request lnes that are numbered from 0 through 15. If two adapters or devces generate nterrupts at the same tme, an Integrated Crcut called the Interrupt Controller determnes whch sgnal s processed frst. Whle IRQ 0 usually receves the hghest prorty, non-maskable nterrupts or NMI's have prorty over all other nterrupts. The upper left-hand corner of Fgure 1 shows schematcally the relatonshp between the nterrupt controller, the IRQ lnes, and the remander of the system. The nterrupt controller prortzes up to 15 ncomng nterrupt sgnals. When an nterrupt nput sgnal goes hgh, the nterrupt controller resets and checks the nterrupt regster. If an nterrupt s n progress, the controller wats untl the current nterrupt s completed before sendng the next nterrupt to the CPU. The CPU responds to the nterrupt request wth a sgnal on the nterrupt acknowledge lne after t completes ts current nstructon. DMA channels DMA channels allow the adapters and ther accompanyng software to communcate wth the system memory. As an example, operator nstructons may tell the CPU to read data from a hard dsk drve and then store the data nto the system memory. When the mcroprocessor needs to move the large blocks of data, another IC called the DMA controller takes control over the address and data buses. As the data transfer begns, the DMA controller tells the mcroprocessor to momentarly halt ts current operaton whle the data transfer takes place through the DMA controller. The use of DMA channels and the DMA controller speeds the data transfer and frees the CPU for other operatons. Although seral and parallel ports do not utlze DMA channels, adapters such as network cards and tape backup nterfaces often use DMA transfers. Each adapter can use the same DMA channel but only f the other devce s not functonng. Two devces may share DMA channel 7, but not smultaneously. Take another look at Fgure 1. The relatonshp between DMA control and the remander of the system s shown as a schematc representaton. The DMA crcutry s shown toward the rght sde of the fgure. Durng drect memory addressng, the CPU s put nto a hold state whle the DMA controllers drve the address and control lnes. Upper memory blocks The upper memory block s the area between the top of the conventonal memory or 640K and the bottom of the extended or expanded memory or 1,024K. The addresses of the upper memory block range from A0000 to F0000 and are reserved for varous purposes. For example, the vdeo adapter may use some, f not all of ts allocated 128K of memory n ths area. Other adapters may use segments of the upper memory blocks; a token rng network adapter wll use 8K at address CC000 for ROM and 16K at address D8000 for RAM. Uses of upper memory block segments cannot overlap. If two adapters are set to request the same segments, nether wll work properly. If the modem and sound card nstalled by Joe request the same block segment, one wll work only when the other s dsabled. Some adapter cards have swtches or jumpers that allow techncans to change the requested memory segments to dfferent areas. Other adapter cards rely on drver software for such changes. Documentaton for the adapters should specfy the area of the upper memory block needed so that the adapter can functon properly. I/O addresses The nput/output address of a devce s the physcal locaton on the system's bus or RAM where ntellgence that allows the adapter to functon s located. Unlke memory addresses, the 1,024 I/O addresses are not desgned for data storage. Wth the I/O addresses, the mcroprocessor can communcate drectly wth adapters and other attached perpheral devces. Each adapter or devce has a unque, hexadecmal I/O address. Because of ths, there s a chance that a conflct could occur. Examples of I/O addresses are 2F8 to 2FF for the seral port two or COM 2 and 3F8 to 3FF for COM 1. Makng a plan What does all ths mean for the techncan? Here's an example: a modem may be assgned to a base address of 02F8 and use COM 3 whle a mouse s assgned to a base address of 03F8 and uses COM 1. Both wll use IRQ 4. Unfortunately, the nterrupt controller cannot determne whch sgnal should be processed frst when the sgnals arrve on the same nterrupt request lne. If the modem s accessed frst, the mouse won't functon correctly. If the moose s used for a Wndows applcaton, the modem won't send or receve data. As you can readly see, the smple nstallaton of an adapter card suddenly becomes more complex. Solvng nterrupt and devce conflcts requres a logcal process rather than the shotgun approach. Start over To consder that logcal approach, let's go back to Joe's problem and see f we can fnd a soluton. Frst, we should remove the just -nstalled nternal modem and sound card from the system. Ths allows us to reset the system back to ts orgnal condton and provdes a workng base for our troubleshootng. As we remove the two devces, we can also check for dsconnected cables or other adapters, such as a vdeo card that may not be locked nto place. The object of ths step s to take the system back to ts orgnal condton; not to create more problems. Check jumpers, swtches Second, we'll take a look at any swtch or jumper settngs that could affect the performance of the adapters. Check both the adapter and the system for the locaton of the swtches and jumpers. Now, double-check your settngs aganst the swtch or jumper postons shown n the manuals that accompany both the system and the adapter. Usually, the manuals wll show default settngs for swtches or November 1995 Electronc Servcng & Technology 43

30 jumpers and wll suggest settngs for specfc IRQ and address needs. Often, because of poor prnt qualty or poor graphcs t s easy to msnterpret those settngs. The default settngs provde a reference pont as you troubleshoot the problems. Sometmes though, those default settngs shown by the manuals wll not match the actual default settngs of the adapter. Document For your thrd step, document whch devces are nstalled or attached to the system. Set up a cross-reference form that lsts the adapters or devces, the desgnated IRQ's, and the base addresses. Lst the slot number occuped by the adapter and, f possble, the DMA channel utlzed by the adapter. Most manufacturers of IBM compatble computers and thrdparty card manufacturers nclude ths type of nformaton wth ther products, but some do not. If you encounter a problem and cannot fnd reference materal, there are several references that contan nformaton on many brands of boards, drves, controllers, network nterface cards, I/O cards, etc. Use dagnostcs Stll unsure about the qualty of nformaton? Use dagnostc software to fnd whch addresses are used or avalable. Mcrosoft ncludes the MSD or Mcrosoft Dagnostc Software wth ts MS-DOS operatng systems for verson sx and above. Dagnostc software also provdes easy access to those settngs. Performng ths type of nventory allows you to dentfy whch adapters or devces are attemptng to use the same IRQ lnes, base addresses, or DMA channels. Set jumpers, swtches Step four n ths process s obvous. Usng the manuals or the dagnostc software, fnd avalable IRQ, base memory addresses, and DMA channels and then set the adapter swtches or jumpers to the new settngs. Some adapter cards may not contan swtches or jumpers. Instead, these adapters have settngs that are encoded nto IC's located on the card. Because of ths, you may need to consder changng settngs on other adapters. Because of newer software technologes, ths step may also requre adjustments to several ponts that nvolve software confguraton. Sometmes, the nstallaton software that accompanes an adapter wll add lnes to the CONFIG-.SYS fle, whch resdes n the root drectory of MS-DOS. The CONFIG.SYS fle s a text fle that lsts a seres of commands that allow a user to confgure the system as needed. When the system starts, the CONFIG.SYS fle controls how MS- DOS starts and confgures the hardware components such as the memory, keyboard, and prnter. See Fgure 2 for an example of a typcal CONFIG.SYS fle. Lnes n the fle refer to the devce drver software that ntalzes the mouse, the SCSI controller card, and the external CD-ROM reader. Devce drver commands n the CONFIG.SYS fle nstall the drver nto the system memory. As long as the system stays on the current CON- FIG.SYS fle, the drver works as part of the system software. The drver software sets the operatng parameters for the attached devces. AUTOEXEC.BAT Lke the CONFIG.SYS, the AUTO- EXEC.BAT fle s an unformatted text fle and may be changed by usng the lne edtor command that s avalable through MS-DOS or the Notepad software ncluded wth Wndows. Versons 5 through 6.22 of MS-DOS utlze the EDIT command; older versons use the EDLIN command. To use the edt command, change to the DOS drectory and type EDIT at the prompt (C:\DOS). The edt software s menu -drven and easy -to -use. Manuals that arrve wth the MS-DOS operatng software provde a complete set of nstructons for usng the edt command. Before edtng the CONFIG.SYS fle, screen prnt the orgnal as a reference pont. Re -bootng the system wll ntalze the newly -changed CONFIG-.SYS fle. The AUTOEXEC.BAT fle s a smple batch program that MS-DOS runs mmedately after followng the commands lsted n the CONFIG.SYS FILE. An example of an AUTOEXEC.BAT fle s shown n Fgure 3. INI fles In addton to the CONFIG.SYS fle and AUTOEXEC.BAT fle, nstallaton software often modfes the SYSTEM-.INI and WIN.INI fles that resde n the Wndows drectory. Both fles ntalze the Mcrosoft Wndows software and lst settngs that customze that software for specfc hardware applcatons. As wth the CONFIG.SYS fle, the SYSTEMINI and WIN.INI fles may be edted through the edt command. As before, screen prnt the orgnal as a reference pont. Errors n ether the CONFIG.SYS or the SYS- TEM.INI fle may cause the system to lock durng ts ntalzaton process. Along wth consderng those mportant DOS fles, also remember to check the verson and type of the drver software that arrves wth the card or perpheral devce. Some lower versons of devce drver software may not work wth the ntended card or devce. When a msmatch of ths type occurs, an error message that says somethng lke "devce not recognzed" may appear on the screen. Most manufacturers offer bulletn board servces wth lstngs of devce drvers and devce drver defntons. Techncans can download those fles from the manufacturer server computer through a modem. Try agan Now that you've changed the jumper or swtch settngs and have confgured the system software, renstall the adapter nto ts slot and test ts performance. The testng of performance should nclude not only the adapter but all parts of the computer system. Many techncans wll conclude that the problem s resolved and then later fnd that they've created new ones. If the frst adapter or other adapters fal to operate, look for other avalable IRQ, memory address, or DMA channel settngs. As mentoned, solvng the problem may requre changes to other already - nstalled adapters. Occasonally, the only opton s removng other adapters and attemptng to modfy those IRQ, memory address, and DMA channel requrements. Ths opton also means that you would need to go back to the startng pont of our procedures. Brefly, that nvolves: Removng the adapter and resettng the system to ts orgnal settngs. Verfyng the settngs on the adapter selected for modfcaton along wth checkng adapter and system manuals. Makng a lst of nstalled adapters and devces and checkng for possble conflctng demands on system resources. 44 Electronc Servcng & Technology November 1995

31 DEVICE=C:\DOSNHIMEM.SYS DEVICE=C:\DOS\EMM386.EXE NOEMS FILES=30 BUFFERS=30 DEVICE=C:\DEVICE\SMARTDRV.EXE DEVICE=C:\MOUSE\MOUSE.SYS DEVICEHIGH=C:\PIONEER\SCSI.SYS /D: LASTDRIVE=Z DOS=HIGH,UMB TIME DATE PATH=C:\ C:\DOS;C:\WINDOWS;C:\PIONEER PROMPT $P$G DOSKEY SMARTDRV WIN Fgure 2. CONFIG.SYS fle s a text fle that lsts a seres of commands that allow a user to confgure the system as needed. When the system starts, the CONFIG.SYS fle controls how MS-DOS starts and confgures the hardware components such as the memory, keyboard, and prnter. Ths s an example of a typcal CONFIG.SYS fle. Fgure 3. The AUTOEXEC.EAT fle, an example of whch s shown here, s a smple batch program that MS-DOS runs mmedately after followng the commands lsted n the CONFIG.SYS FILE. After fndng avalable resources, change the selected adapter so that t uses those resources that are avalable. Renstall the selected adapter and check the performance of all of the adapters or attached devces. Followng ths procedure should allow you to solve most problems encountered when nstallng new adapters nto a mcrocomputer system. There s, however, a small porton of adapter nstallatons that wll fall outsde of these procedures. Workng wth these cases may requre some phone calls to the techncal support teams that support the ndvdual adapters or devces. As you prepare to talk wth support personnel, remember to keep a prntout of the orgnal CONFIG.SYS and AUTOEXEC.BAT fles handy. Also, check for any model or seral numbers that may be slk-screened onto the adapter card. Record both the default settngs and the modfed settngs for use durng your conversatons wth techncal support. Some recommended books Asde from the techncal reference manuals, several books are also excellent sources of nformaton for techncans workng wth mcrocomputer upgrades. Scott Mueller' "Upgradng and Reparng PC's" (publshed by the QUE Corporaton) provdes charts and nformaton that cover IRQ's, DMA's, and I/O addresses. In addton, Mueller's text lsts phone numbers and addresses for a large number of system and adapter manufacturers. For begnnng techncans, an older text n the Howard W. Sams lbrary, "Mcrocomputer Troubleshootng and Repar" by John Stephenson and Bob Cahll, provdes easy -to -nterpret nformaton about mcrocomputer systems. Two new texts from WEKA Publshng, "How to Repar and Upgrade Computers and Perpherals" and "How to Maxmze Your PC" also provde up-todate reference charts about adapter cards, DMA channel requrements, I/O port addresses, and hardware nterrupts. Use Your Free Reader Servce Card For More Informaton On Companes Advertsng In Ths Issue. #c 1' FAXD [Nal IN1IRNET Address TRITRCNCSOool com large enough to serve yoj - small enough to know youl authorzed parts, accessores & lterature premer dstrbutor for: sc RCA ves Untversal Parts RCA PRC1SCAN GENERAL a ELECTRIC L, and DI MS'S Dgtal Satellte System authorzed parts, accesscres & lterature dstrbutor for: alum DENON E SCOTT EZ'merson. Panasonc. PHILCO *Matsushta CASIO FISHER Qua-gar. SYLVANIA MAGNAVOX SHARP. Thchncs Crcle 165) on Reply Card November 1995 Electronc Servcng & Technology 45

32 Servcng TV horzontal foldover problems By Homer L. Davdson Horzontal foldover problems n TV sets are not as common as vertcal foldover, but when t occurs you must be able to recognze the symptoms and know the possble defectve components. Horzontal foldover can be caused by a defectve damper dode, safety or hold down capactors n the horzontal output collector crcuts or capactors n pncushon transformer crcuts (Fgure 1). Horzontal foldover often occurs at the extreme rght sde of the TV raster. When you encounter a set that has horzontal foldover, nspect the horzontal output crcuts. A leaky horzontal output transstor, trace or retrace SCR, or a leaky flyback can cause some form of foldover. Open bypass capactors n the hgh voltage regulator or SCR horzontal crcuts can cause some type of horzontal lnearty problem, or foldover. Defectve safety capactors n the horzontal output crcuts produce foldover. Open or poor soldered termnals of reactors and regulaton transformers can cause horzontal foldover (Fgure 2). Defectve safety capactors Safety capactors n the horzontal output crcuts can cause horzontal foldover and poor lnearty. I have seen cases n whch the horzontal output transformer s replaced but the foldover problem perssts. Often when safety or hold down capactors become open or change value the hgh voltage at the pcture tube wll ncrease. If one of the safety capactors n seres wth another capactor becomes open, the voltage may ncrease accompaned by horzontal foldover. A change n the value of the safety capactor can result n mproper horzontal lnearty and foldover, accompaned by ncorrect HV at the pcture tube (HV may be ether too hgh or too low). A leaky safety capactor may damage the horzontal transstor, and/or blow lne and secondary fuses. Davdson s a TV servcng consultant for ES&T. - xgjlsmsvhre 14)fre& sf "t.41 te'r`j Fgure 1. Horzontal foldover n the TV chasss may occur on the rght hand sde and center of the TV pcture or raster. Replace safety capactors wth the manufacturer's orgnal part number or an exact unversal replacement. When orgnal ones are not avalable, replace wth 2KV voltage ratng safety capactors. Remember the safety capactor s a crtcal safety component. Check carefully for burned resstors and shorted turns of wndngs n pncushon transformers when horzontal Fgure 2. Check the pncushon and regulator transformer for poor termnal connectons when the symptom s vertcal foldover. 46 Electronc Servcng & Technology November 1995

33 T101 FLYBACK SCR101 TRACE R ACR1 C17 390p F R C10 1.5µF 01 HV REG CR6 R8 10Kl C F OPEN Fgure 3. Capactor C12 (0.18pF) bypass capactor n the hgh voltage and flyback crcuts of the RCA CTC44A chasss can produce horzontal foldover. ee.1.4,4e4.44 tot4a-14.e44- foldover s caused by problems n the pncushon crcuts. Foldover problems n older sets If you encounter foldover problems n older TV chasss that have trace and retrace SCR's, suspect a leaky SCR, open gate nput col, or bypass capactors. Check all bypass and couplng capactors n the SCR horzontal output. Use a capactance meter to try to locate the defectve capactor, or shunt each capactor wth a known -good capactor untl the problem s corrected. The capactor you Fgure 4. Capactor C702 n a General Electrc YME chasss was the cause of foldover. DALBANI CORPORATION 4225 N.W. 72 ND. AVE. MIAMI, FLORIDA, TEL : (305) FAX : (305) Crcle (56) on Reply Card Satellte Dealers Assocaton (A not -for-proft assocaton) Jon Us Regonal Tech Semnars Electroncs Technology School, Satellte/Antenna/MATV, and Busness Management Schools for small electroncs servce dealers CSI Certfcaton Become a CSI, Certfed Satellte Installer, or a CET, (Satellte Journeyman). Jon those makng a professon of the busness. Call for nearest test ste. (360 stes) Tranng Materals Semnar Vdeos, UCANDO Tranng Vdeos. FCC and CET study materals - books and computer dsks; monographs and a full tme offce to provde dealer and techncan help - when you need t. Call for member applcaton N Jackson Greencastle, In Crcle (79) on Reply Card November 1995 Electronc Servcng & Technology 47

34 0451 HORIZONTAL DRIVER HORIZONTAL INPUT T451 DRIVER TRANSFORMER 0452 HORIZONTAL OUTPUT I C pF I I C466 C464 C µF µF µF T452 FLYBACK LOW C465 - C478 C pF 0.018µF 0.001µF µF 3.31(0 110V 110V Fgure 5. Check all capactors n the collector output crcuts of Q452 when the problem s poor blearly and foldover problems. shunted when the problem dsappeared s the bad one; replace t. Check each capactor for open or leaky condtons. In one RCA CTC44 chasss, I found C12 (0.18pF) open to chasss ground (Fgure 3). You ordnarly expect bypass capactors to become leaky. They seldom open. It s best to replace these odd capactors wth the exact part number. Intermttent condtons were noted n an early RCA CTC74 chasss wth the sdes pulled nward, and horzontal fold - over n the center of the pcture. A common cause of ths symptom was a blown fusble resstor RF401. I replaced the horzontal oscllator but the problem remaned. After several other correctve steps were taken wth no mprovement, I replaced the C507 (0.18pF) bypass capactor. The foldover problem dsappeared. Another possble cause of horzontal foldover n ths set s poor nput reactor transformer (T402) board connectons. supply voltage, I dsconnected the yoke from the crcut. Wth the red -yellow lead dsconnected, the raster was stll folded over. Damper dode Y201 and boost dode Y704 tested normal. When I checked safety capactor C702 n the crcut, the pF capactor appeared open. When I tested t out of the crcut, however, t tested normal. C704 tested normal wth one lead dsconnected from the crcut. The only other component n the crcut was the horzontal output transformer (T710). I presumed that t had to be the culprt. I ordered a replacement for T710 and nstalled t when t came n. Unfortunately, replacng T710 dd not solve the foldover problem. The foldover was stll there but now there was no black lne at the sde of the raster. Because many foldover problems are caused by defectve safety capactors, I replaced C702 and C704. I replaced C702 wth a ' 1.5KV orgnal replace - General Electrc YME chasss foldover When the horzontal output crcut s unfamlar t may take more tme for the techncan to troubleshoot a foldover problem. When the pcture came on n a General Electrc YME chasss, horzontal foldover at the rght sde occurred accompaned by a black area at the edge of the pcture tube. After checkng the horzontal output transstor, the drve waveform and the Fgure 6. Make sure all components n the horzontal output crcuts are normal before removng and replacng the output transformer. 48 Electronc Servcng & Technology November 1995

35 FROM HORIZONTAL PRE -DRIVER R HORIZONTAL DRIVER CR3210 TX3205 DRIVER TRANSFORMER n HORIZONTAL OUTPUT R REPLACE WITH TRANSISTOR R GX µF REPLACE TX3204 FLYBACK TRANSFORMER +12.6V +28.4V TO MULTI VIBRATOR CIRCUITS $ +118V Fgure 7. Replacng leaky Q3208, R3242, and GX3212 restored the dead set to lfe and corrected the horzontal foldover condton n ths Zenth televson set. ment. Vctory appeared n sght. When the chasss was fred up agan, the foldover problem was elmnated. I have snce found ths safety capactor to be the cause of foldover n many smlar sets. Foldover follows horzontal crcut problems The man fuse n a Sanyo AVM255 TV set was blown. I replaced the fuse but t blew agan as soon as power was appled. A voltage measurement at the man flter capactor n the low -voltage power supply ndcated leakage somewhere. I checked all slcon dodes and found them to be normal. The low -voltage source feedng the +110V source ndcated an overloaded component. A resstance check between the collector of horzontal output transstor (Q452) and the chasss ground showed a 0.175I short (Fgure 5). A look at the schematc revealed that the damper dode was located n the same package wth the horzontal output transstor. I removed Q452 from the heat snk and checked t wth the DMM. Ths component was shorted between the emtter and collector termnals. After replacng Q452 wth a unversal replacement, I plugged the set nto a varable lne transformer. I connected a voltmeter at the 3.30 solaton resstor to montor low voltage to the horzontal output transstor. As I slowly rased the voltage to the set, I noted that the voltage at the flyback was lower than t should be and Q452 was begnnng to run qute warm. I shut the set down n order to perform some other tests. After checkng the varous components aganst the specfed values on the schematc, I decded to advance the lne voltage wth the scope connected to the base of the horzontal drver transstor (Q451). The drve voltage at ths pont was low. Ths condton meant that ether the horzontal oscllator drve waveform was mssng or one of the components n the horzontal output crcuts was leaky. I checked all safety capactors n the output crcut usng n -crcut resstance tests. None of these capactors were leaky. I dsconnected the yoke lead from the flyback crcut but the stuaton ddn't change. The prmary wndng of T452 seemed normal. However, because experence has shown that a defectve flyback can be the reason for destructon of the horzontal output transstor, I ordered an exact manufacturer's replacement for the flyback (Fgure 6). After several weeks, the replacement flyback transformer arrved. I nstalled t, reconnected the yoke, and the hgh voltage came up, as dd the raster and pcture. Although replacement of the defectve flyback solved the horzontal output problems, there was horzontal foldover at the rght edge of the pcture. No doubt Fgure 8. If you locate the flyback, horzontal out jut, and pncushon transformer, you wll fnd the safety capactors nearby. November 1995 Electronc Servcng & Technology 49

36 FROM HORIZONTAL > DRIVER T HORIZONTAL OUTPUT CHECK, ahl C4416 C p F µF L501 YOKE T4402 FLYBACK I +140V 0.25µF µF D CHECK V +140V Fgure 9. Horzontal foldover may reman after a shorted horzontal output transstor has been replaced wth a good component. one of the safety capactors was defectve. I agan checked each safety capactor n the crcut. None of them appeared to be open or leaky. Possbly one of the capactors was openng up under load. Snce there were four safety capactors, all of the same value, I decded to shunt each one wth a 0.018µF 2KV safety capactor. When I shunted C464 wth another capactor the foldover problem dsappeared. I replaced both C464 and C465, fnalzng the soluton to the horzontal foldover. Dead Zenth SA -1927W chasss The chasss of a Zenth SA TV set was completely dead. The man fuse was blown and there was no +118V supply from the low voltage power supply. A resstance measurement from the collector (metal) to common ground ndcated a leaky output transstor (Q3208) or damper dode. I removed Q3208 from the heat snk and checked t wth the ohmmeter. It was shorted (Fgure 7). Transstor Q3208 can be replaced wth the orgnal part number or a unversal RCA SK9119 output transstor. After I replaced the transstor and agan appled power to the set there was a motorboatng sound from the speaker. I agan checked Q3208 and Q3206 n the crcut and they tested good. Resstance tests at the base and emtter termnals of the horzontal output transstor revealed that emtter resstor R3242 (0.180) was open. No doubt when the output of the transstor shorted, the excessve current destroyed R3242. Wth both Q3208 and R3242 replaced I plugged the set nto a varable solaton transformer and connected the scope to the base of Q3208. I slowly rased the lne voltage untl the set produced a raster and pcture. At the rght sde of the pcture a slght foldover and a drve lne was found. At frst I suspected the flyback snce the output transstor had been shorted. I checked all parts n the horzontal output crcuts. They appeared normal. Because I know that safety capactors can cause foldover problems and an ncrease n HV, I replaced capactor CX (.0082µF 1.8KV). When I agan appled power to the set, a small foldover lne near the edge of the pcture remaned. I replaced Q3208 wth another unversal replacement, but the horzontal foldover problem remaned. I pcked up a replacement for the horzontal output transstor ( ) from a local Zenth dealer, and nstalled t. Ths tme when I appled power the pcture returned to normal. Ths Zenth chasss was restored to normal when the defectve horzontal output transmtter was replaced wth an exact manufacturer's replacement component, a new resstor and g safety capactor. In some cases there s no substtute for an exact manufacturers replacement component. Poor horzontal lnearty wth foldover Whenever you encounter a set wth poor horzontal lnearty accompaned by foldover, try to locate the horzontal output transstor and flyback transformer. (Fgure 8). You should be able to locate safety capactors nearby. Often safety capactors, n ths case, C446 and C447, can also cause excessve hgh voltage and horzontal foldover. Electrolytc and bypass capactors n the yoke crcuts can cause poor horzontal lnearty and horzontal foldover problems. If the symptom s horzontal foldover and a safety capactor appears to be open, put a known -good capactor n parallel wth the suspect capactor to see f that corrects the problem. Clp or tack n bypass and electrolytc capactors n parallel wth suspected capactors n the yoke and horzontal crcuts f the symptom s vertcal lnes and poor horzontal lnearty. Dsconnect one end of the safety capactor to test t for leakage, and measure ts capactance. Often, a leaky capactor n the B+ voltage crcuts of the horzontal output transstor, yoke, and flyback crcuts may cause the lne and secondary fuses to open (Fgure 9). Sometmes the horzontal output transstor may be damaged wth a shorted or leaky capactor n the output crcuts. Remember, horzontal foldover may reman after you replace a leaky horzontal output transstor. M 50 Electronc Servcng & Technology November 1995

37 Constructng a pencl probe By Roger D. Redden Sometmes, makng a smple connecton s an exercse n frustraton. Does ths sound famlar? You want to make a connecton to a component lead, but t s surrounded by a badland of other components that prevent your fngers from operatng a typcal grabber devce. Or, you can get to t, but the lead s flat aganst the board, and the hook of the grabber won't slp under t. If you've fought these vllans, then buld ths trusty probe to defeat them both. The long barrel allows access to recessed areas, and the pncher jaws wll grasp a lead lyng flat aganst a crcut board. As a fnal bonus, f you have the needed tems on hand, whch s very possble, t's really nexpensve to construct. The lower drawng of Fgure 1 shows the completed probe and should gve you an dea of how t's used. When you press the eraser, the pncher jaws extend and open so they can straddle the component Redden s owner and operator of a consumer electroncs servce center. lead, and when the eraser s released, the jaws clamp on the lead. I'm confdent you can envson how ths probe can make your connecton easer. Materal and costs Undoubtedly, you've surmsed that ths probe s made from a pencl. Specfcally, t's a Bc, nonrefllable, mechancal pencl contanng three 0.7mm leads. The upper drawng of Fgure 1 depcts the pencl, whch usually has a black body whle the clp and eraser holder s of a contrastng color. Ths s the common pencl substtute usually sold n a bag contanng 5 or 10 of them. The bag usually costs about $1 to $3 and s avalable n most places where school supples are sold. The prmary tem needed to make the pencl a probe s the sprngwre used to make the jaws, or pnchers, of the probe. The source of ths sprngwre s a pgtal adapter for a 1/4 nch fuse, sometmes called a sprngtal fuse holder, or a sprng - wre clp. Fgure 2B s a drawng of one. Two of these clps allow a pgtal fuse to be replaced wth a plug-n type fuse. Ths tem s stll found n may servce centers. If you have one lyng around, you can fgure t probably cost you about $.35. If you don't have one, you mght be able to get a sngle one from another servce center, If you have to buy a package of 12, t may cost you $5 or $6. Cheaper by the dozen can be a drawback when you need just one. As you can see, the total cost of materals can vary from under $1 f you have these tems on hand, to over $9 f you don't. You'll also need about a foot of stranded, nsulated, hookup wre of about #20 or #22 sze, one nch of 1/4 nch heat shrnk tubng or spaghett, maskng or other tape, a drop of superglue gel or other glue for plastc, and 13/32 nch length of #2 desolderng brad. For tools, you'll need a sharp utlty knfe or razor, a drll, a drll bt slghtly larger than the outsde dameter (OD) of the nsulated wre you use (I used a 5/64 nch bt), needlenosed plers, wrecutters, a small jeweler's screwdrver, a ruler or 3/16" Tp to be cut Cut clp here - End of nner tube Frst drlled hole Clp fts notch, glued to outer tube here Undercut Sprng jaws of probe when extended Tape Soldered wre loop connector Heat shrnk tubng Fgure 1. The upper drawng shows the mechancal pencl before t s altered. and the lower drawng shows the completed probe wth the jaws extended. November 1995 Electronc Servcng & Technology 51

38 Cut tabs, remove stub n drecton of dotted arrow Inner tube Sprngwre fuse holder (A) (B) Coled sprng sldes on before fnal assembly r.-1 1/8" -11 Brad soldered 11/8" from end of sprngwre Wre soldered to bend loop. Loop must slde nto smaller ID of tube (C) Doubled sprngwre Equal dameters = Tnned wre started through drlled hole Fgure 2. A. After the nner tube s wthdrawn from the pencl, the tabs are cut and the stub removed. B, s a drawng of a sprngwre fuseholder. In C, the sprngwre assembly s sld nto the nner tube untl the brad touches the tube's end. The tnned end of the hookup wre s pushed through the drlled hole. other scale wth 1/32 nch dvsons, and a fle (optonal). It takes about one hour to buld the probe. Preparng the sprngwre From now on, I'll refer to the sprng - wre fuse holder as the sprngwre. The frst step n buldng the probe s to unroll the spral part of the sprngwre. The easest way I've found to do ths, s to hold the straght part of the sprngwre wth one hand, and, n the other hand, use the needlenosed plers to repeatedly grasp and unroll the spral. When the spral s unrolled, leave the 90 degree bend at the end of the straght secton so the sprng - wre s n an L shape. Ths bend wll help you prevent the wre from revolvng whle you contnue to straghten the unwound spral. The sprngwre must be relatvely straght. Use the plers to overbend t slghtly about every 1/4 nch along ts length to compensate for ts sprng acton. Clamp t n the plers to help remove small knks -and use your fngers to straghten longer curves. You can combne these and any other methods ntended. I usually spend about ten mnutes on t before I'm satsfed. When the former spral seems straght enough, straghten the 90 degree angle as well. Shapng the sprngwre Havng done all of ths straghtenng, t's tme to bend the sprngwre agan. Fold t n the mddle so the result s smlar n shape to a cotter pn, or a bobby pn. Fgure 2C shows (partly nsde the nner tube) the desred shape. For clarty n the drawng, the two sdes of the sprng - wre are shown slghtly separated, but t's better f they touch, except for the loop where the wre s soldered. After the sprngwre s bent n the mddle, the two ends wll cross each other and have to be corrected by overbendng n the opposte drecton to get the rght shape. Hold the back of the bend n the plers to prevent twstng whle you bend the sdes. It requres patence and persstence, and you probably can't prevent mnor crossng or separatng of the ends, but ths can be partly corrected later as the brad s soldered on, and the correcton completed afterwards. Don't worry f the two sdes of the sprngwre are not exactly the same length; the ends wll be cut later. Bend and adjust the two sdes of the sprngwre as needed so that they le closely parallel. The small loop formed by the bend should be large enough for the hookup wre to go through, but small enough, about 3/32 nches, to slde nto the small end of the nner tube. Now, set the sprngwre asde temporarly whle you begn to work on the pencl. Gettng the lead out The lead needs to be removed from the pencl. Dong lots of wrtng wth the pencl s the thrfty way to empty t. But f you just want to get the lead out-and fast-here's how: Remove the eraser, whch must be done anyway, by pullng, rockng, and twstng t whle holdng the socket t sts n. Don't lose the eraser. Turn the pencl tp up, and the lead wll fall out. Push the eraser socket a few tmes to start the last lead out of the tp of the pencl. Press the socket and hold t, and the thrd lead can now easly be pulled out of the tp of the pencl. Drllng for the wre ext You need to drll a hole through both the outer and nner tubes of the pencl, opposte the mddle of the clp as shown at the top of Fgure 1. Use a drll bt slghtly larger than the OD of your hookup wre. Twstng the pont of the utlty knfe on the spot the hole wll be drlled can help start the bt n the rght place. Stop drllng when the drll reaches the hollow space of the nner tube, and remove the drll bt. 52 Electronc Servcng & Technology November 1995

39 Second two holes drlled n outer tube only Fgure 3. A. A rectangular slot s formed n the outer tube by drllng two addtonal holes and trmmng away the remnants. In B, the ends of the extended sprngwre are cut 1/4 nch from the end of the outer tube. C. Bend the jaws as shown n the upper drawng. The jaws should close before enterng the barrel of the pencl as shown n the lower drawng. Both drawngs are about 3 tmes the actual sze. Press the eraser socket a couple of tmes to break loose any drllng chps lodged between the tubes, and allow them to fall out the open end of the tube. Separatng and preparng the tubes Removng the nner tube from the outer tube, or barrel of the pencl requres lttle force. Hold the barrel n one hand and pull straght out on the eraser socket wth the other hand (a quck, but controlled jerk helps). When the tubes separate and you pull the nner one out, be sure to save the coled sprng at the end. After you remove the coled sprng, you'll fnd two plastc tabs. Cut these tabs just below where they come together, as shown n Fgure 2A. Press the protrudng end of the stub aganst the bench untl t breaks loose and recedes nto the tube, and then use the jeweler's screwdrver to press t farther nto the tube. Tap the back of the tube on the bench so the stub falls out, and lay the tube asde. The outer tube needs a rectangular slot just behnd the mountng shoulder of the clp. My method was to drll two more holes, one on each sde of the one already drlled, and cut out the remnants wth a sharp utlty knfe. The slot should be the same approxmate length as the shoulder of the clp, and as wde as the dameter of the drlled hole, as shown n Fgure 3A. Next, cut off the end of the outer tube 3/16 nches from the tp, as shown n the upper part of Fgure 1. A good way to keep the cut the same dstance from the tp all of the way around the tube s to lay the sde of the pencl tp aganst the bench and spn t slowly whle holdng the utlty knfe n one place.the cut wll probably leave burrs or a plastc lp nsde the tube. Remove ths wth the jeweler's screwdrver or, beng careful not to cut the barrel, wth the tp of the utlty knfe. Now cut the clp of the pencl about 1/16 nches before the front of the mountng shoulder as shown n the upper part of Fgure 1. Smooth the sharp corners of the cut ends. Undercut the shoulder overhang so the clp wll ft under t as shown n the lower part of Fgure 1. Glue the mddle of the clp to the barrel of the tube as shown. Hangng two fngers over ths crossbar makes t easer to squeeze the eraser when usng the probe. Lay the outer tube asde for now. Completng the sprngwre assembly For the steps n ths secton, refer to Fgure 2C. Strp 1/4 nch of nsulaton off one end of the hookup wre and solder t to the loop of the sprngwre. Strp 1/2 nch of nsulaton from the other end of the hookup wre and tn the bare wre. Roll the 13/32 nch length of desolderng brad between your fngers to round t, then wrap t around the sprngwre leads about 1-1/8 nches from ther ends, as shown. After t's n place, use needle - nosed plers to flatten t nto the approxmate shape of a washer or thn doughnut. The desred result s to have the thn doughnut of brad the same dameter as the end of the nner tube, allowng for some slght swellng caused by fllng t wth solder. Check that the brad s 1-1/8 nches from the shortest end of the sprngwre, then algn the two sprngwre sdes so they are as parallel and as close fttng as possble, holdng them n the needlenosed plers, whch are placed on the sde of the brad that gves the best results. Ths s the partal correcton referred to earler for the problem of the sprngwre ends crossng over each other. Wth the solderng ron lyng on the bench, touch the brad to the ron and supply just enough solder to fll the brad and make a good connecton to the sprng - wre. Excess solder could cause a bulge that would prevent proper sldng acton between the two tubes. After solderng, do any further needed algnng (fnal correctons) to the ends of the sprngwre extendng past the brad. Insert the hookup wre nto the small end of the nner tube and push t out the eraser holder end, contnung untl the brad doughnut s flush aganst the small end of the tube. Form a loose loop n the hookup wre, bend a gentle curve n the tnned etxl, and usng the jeweler's screwdrver f needed, start the tp out of the drlled hole as shown. Fnal assembly To reassemble the two tubes, place the coled sprng over the sprngwre ends, and begn sldng the nner tube nto the outer tube. When the tnned wre protrudng through the sde of the nner tube reaches the rm of the outer tube, make sure t's algned wth the slot n the outer tube. Press the tnned wre back nto the nner tube just enough to allow the nner tube to slp nto the outer tube. Press the eraser holder wth enough pressure that the drlled hole n the nner tube s vsble n the slot of the outer tube. Work the tp of the hookup wre out through the slot, usng the jeweler's November 1995 Electronc Servcng & Technology 53

40 screwdrver and needlenosed plers f needed, and pull the wre out through the slot. Contnue to pull the wre through the slot untl the loop goes nsde the nner tube and just clears the bottom of the eraser holder socket. Renstall the eraser by twstng t back nto the holder. The wre extng through the slot prevents the nner tube from fallng out when t's released. If everythng s workng correctly so far, pressng the eraser holder should cause the nner tube to move forward about 1/4 nch, and t should sprng back when you release the holder. Formng the jaws Now that the probe s assembled, t's tme to partally cut, break, and bend the sprngwre to make the jaws. There are two reasons for only partally cuttng the sprngwre. Frst, the brttle wre fles when cut, and could cause eye njury. Because of ths, you should wear safety glasses n case you nadvertently cut through the wre. Second, the pressure requred to cut through the sprngwre could damage the edge of precson cutters. So that you won't need three hands, set the rear of the eraser on the top of the bench and press down on the outer tube, or barrel, so that the sprngwre s fully extended. Measure 1/4 nch from the cut end of the outer tube and clamp the jaws of the sdecutters across both sprngwre ends at that pont. Squeeze the cutters untl the sprngwre end closest to the cutters' pvot pn s cut about halfway through (1/4 through on the front and back sdes). Release the cutters and rotate the pencl 180 degrees so the other sprngwre s next to the cutters' pvot pn and repeat the partal cut. Usng the plers, bend each end of the sprngwres back and forth at the partal cut, about 30 degrees from ts straght lne, untl t breaks off. Wth the sprngwre fully extended, bend the jaws as shown n the upper drawng of Fgure 3C. Frst bend the two sdes of the sprngw re out so the tps are about 3/16 nches apart. Then, about 1/16 nches back from the tps, and makng the bends as dentcal as possble, bend the ends back toward the center. The tps should now be open about 3/32 nches. As the eraser s released, the nner cor- Once agan ths year's Profax Schematcs Specal ssue wll be offerng a prze drawng. Every reader s elgble to wn przes from: Sencore Fluke Tentel Electronc Software Developers Premum Parts + Don't forget to fll n all the nformaton requred on the entry card and pass the other one along --:"-- to an assocate. (No duplcates please). Servcng & Technology Electronc Desgn Specalsts Ram Software TV Man Sales & Servce Phlps atecttlutc ners of the jaws should come together shortly before gong nsde the barrel, as n the lower drawng of Fgure 3C. When the jaws are bent correctly, the frcton from the mouth of the barrel wll cause the jaws to slow before gong nsde the barrel, possbly wth a slght snappng acton. Some tral and error adjustments may be requred to get t rght. An optonal mprovement to the jaws s to flatten the tps by flng straght across them, ths allows the pnchng nner part of the tps to approach closer to a crcut board. For the flng, extend the jaws about 1/16 nches wth the tps stll together, and use lght strokes of the fle to avod msalgnng the jaws. Stop flng when about half of the outer tps are removed, as shown n the lower part of 3C. Connectng to the hookup wre Numerous ways can be devsed to connect to the probe's hookup wre, such as addng a small allgator clp, or makng a permanent soldered connecton to a test equpment lead. I chose to use a smple nsulated loop whch can be clamped n the hook of a scope probe or the jaws of a small allgator clp. Many DMM test probes have an allgator clp adapter whch wll clamp to ths loop. Clampng one allgator clp from a jumper lead to the probe can gve a dfferent and useful jumper. Dependng on your needs, you may want to shorten the hookup wre before dong ths step. As shown n the lower part of Fgure 1, the loop s just a small crcle made of the hookup wre soldered to tself, then enclosed n an nch long pece of heat shrnk tubng or spaghett, whch s then taped to the nsulaton of the wre. A pnch of cauton Certanly ths probe wll not solve all of your connecton problems. It's neffectve at clampng to short leads protrudng from the bottom of a crcut board. And though I've notced no effect on waveforms at vdeo frequences, t's only reasonable that hgher frequency waveforms would be degraded. Also, there's no sheldng to prevent pckup of strong unwanted sgnals. Other potental shortcomngs are possble. But, snce I've made ths probe, few tems to be tested have made t through my shop wthout feelng the np of ts lttle pnchers. 54 Electronc Servcng & Technology November 1995

41 Photofacts CROSLEY GCT 2505M 3541 CT-20R12T 3542 CT2746B NC -44A 3541 CT-20R3T B509-00AA 3538 CTN-3176S 3539 JVC DAEWOO AV-31BM PHILIPS CN E615-00AA 3545 DTQ-2605FC P200C DTQ-2605FCG 3551 MITSUBISHI 25B502-00AA 3550 DTQ-2605FM 3551 CS A T290C DTQ-2605FMG 3551 CS DTQ-2605FN 3551 XM DTQ-2605FNG 3551 RCA E13205BKF PANASONIC E13205BKF FISHER ADP TX825TD A8Y AEDP FVH-960 VCR -268 ALDP PC AMDP TOSHIBA ANDP CF27D CT-13R12T 3540 TAC GOLDSTAR CT-13R13T 3540 TAC CN26B CT-13R22T 3544 TV20D W REWORK TECHNOLOGY FROM DENON Sngle hot ar nozzle elmnates the need for multple heads and makes t easy to operate. Also removes BGA. Crcle (75) on Reply Card SC7000 Desolderng Tool SMD removal kt avalable. DEN-CN INSTRUMENTS, db 2580 Corporate Place F-103 Monterey Park, CA Toll Free (800) FAX (213) INC. November 1995 Electronc Servcng & Technology 57

42 What do you know about electroncs? Vacuum tubes By Sam Wlson Televson s beng blamed for everythng these days. But, I say, f you watch TV over a very long perod of tme you wll pck up gems of wsdom. You may not agree wth the phlosophcal vewponts, but you wll agree that they provoke thought. Here are two examples: Regardng success: "The hardest thng about gettng to the top s to get through the crowd at the bottom." (Rockford Fles) By a confrmed bachelor: "A man needs a woman lke a fsh needs a bcycle." (For the women who read ths column: nterchange the words man and woman.) Don't throw away your 6SN7s A company called George Kaye Audo Labs s makng a new tube tester that costs over $500. Don't confuse ths tube tester wth your favorte old Hckock tester. That old favorte dd a fne job of separatng good and bad, but, t was never ntended to gve an n-depth analyss of a tube's condton. I have to be very careful how I word the followng, but, I feel t must be sad. At the very menton of the word "vacuum tube" or "relay" there are some people who go nto hold. Those people are not techncans. They call themselves "admnstrators." They are people who have worked ther way nto postons where they control what s beng taught and what nformaton s beng used n tests. To paraphrase the late Presdent, Harry Truman-they know as much about what s happenng n electroncs as a pg knows about Sunday. Who uses vacuum tubes n ths day and age? Well, for one example, people n the broadcast ndustry. Despte the fact that certan admnstrators have announced that tubes and relays are dead, there are people who stll use them! Not too long ago I quoted the Wall Street Journal artcle that told about some manufacturers who make vacuum -tube audo equpment. Who buys ths type of Wlson s the electroncs theory consultant for ES&T. equpment? People who clam that transstor audo systems just don't sound as good as tube equpment. I have a znc ear. I can't tell the dfference between the sounds made from a bass drum from those made by a tuba. am not even qualfed to make a guess as to whch type of equpment sounds best. However, when professonal muscans say tube equpment sounds better I am not dumb enough to argue wth them. I do know that there has never been any test equpment that can dentfy that dfference n sound qualty, but I'm not sure that proves anythng. If you don't beleve tubes are beng used today fnd a way to get nto a 50,000 watt broadcast staton and start countng. The GROL Now lsten carefully-the "new" FCC lcenses are called GROL (General Rado Operator Lcense). Every queston on the FCC test has been released to the publc along wth the answers. I am a co-author (wth Joe Rsse) of two books on the FCC GROL tests. I have been through every queston and every answer. Joe Rsse also went through every queston and answer. There sn't any coverage on tubes n any part of the new FCC test. The test s supposed to be a method of determnng whether a techncan s qualfed to work n the broadcast ndustry today. If a broadcast techncan s lkely to be nvolved wth tubes why don't they have anythng about tubes n the FCC lcense? We're back to those admnstrators agan. To them, tube s a four-letter word. You stll don't beleve me? Take a look at the latest textbooks for techncans. Look at the trade school currcula. Before you send me a nasty letter askng why I don't have tube theory n my books, let me tell you somethng about wrtng books. One reason for wrtng techncal books s to (hopefully) get a few pennes n royalty money. I hope that doesn't spol an mage. If a book doesn't sell there are no royaltes. So, the people who buy books make the fnal decson on whether a book wll be used for tranng. I was born on Frday, but, not last Frday! '(Incdentally, f you are an admnstrator you should dsregard all of the bad thngs sad about admnstrators. It's really not my fault. Norma wrote t!) The lfetme of batteres You and I both know that a battery s a combnaton of cells. However, the publc seems to have trouble wth that dstncton. We see ads n newspapers about a sale of flashlght batteres. Here n Florda we are warned that we must always make sure that we have a good supply of flashlght "batteres" on hand when the bg wnd descends upon us. If you buy cells every tme you get a warnng you would have to buld an extra room to house them. When the last hurrcane was about to ht our town the rado and TV announcers had old people half scared out of ther mnds. In one nstructon that was passed out people were to seek shelter n local school audtorums, and, n another nstructon people were warned to stay away from the audtorums. After the bg wnd, people start countng up ther supples. You never know when the next breeze wll come roarng down the street. One announcer sad to keep your cells n your refrgerator and they wll last longer. That s true. Another announcer sad to get everythng out of the refrgerator because the electrcty was sure to go OFF. That was also true. If you do store cells n the refrgerator (but never n the freezer!) you must handle them very carefully untl they get back to room temperature. The seals n cold cells become very brttle! Allow the cells to get back to room temperature gradually n order to avod condensaton and a leakage problem. How long should you keep those batteres? A battery has a shelf lfe, accordng to manufacturers, that s equal to the 58 Electronc Servcng & Technology November 1995

43 amount of tme t takes for ts termnal voltage to drop to 90% of ts rated value when t s stored at a temperature of 70F. For example, alkalne and mercury cells have shelf lves up to two years. Carbon -znc (LeClanche) cells have slghtly shorter lves. The lfetme of electrolytc capactors Note: tantalum capactors are hermetcally sealed and have a longer shelf lfe than the alumnum types. Ths s a dscusson about alumnum electrolytcs. If you are gong to make a capactor wth a hgh capactance value n a small package your best choce s to use a very thn delectrc materal. That s the theory behnd the operaton of electrolytc capactors. Ther delectrcs are a thn coatng of oxde materal. Electrolytc capactors do not last forever. The thn delectrc materal n electrolytcs breaks down over tme. Ther shelf lfe s shortened when electrolytcs are stored n hot and/or damp places. Alumnum electrolytcs can be stored n dry, cool places for up to two years. Durng that tme you need to reform the delectrc materal every two months. You reform the delectrc by connectng a DC voltage across the capactor. Use a current -lmtng resstor. Other types of capactors (ceramc dscs, mca, plastc, etc.) have a shelf lfe of about fve years. That's assumng you store them n a dry place. Also, as wth electrolytcs, you wll hasten ther deteroraton f you put them where the temperature swngs. Important notce Dd you purchase ether (or both) of the followng books by Sam Wlson and Joseph A. Rsse: Communcatons Lcensng and Certfcaton Examnatons-The Complete TAB Reference. Practce Tests for Communcatons Lcensng and Certfcaton Examnatons - The Complete TAB Reference. As often happens, some errors got nto the frst edtons. For a free copy of correctons wrte to me n care of ES&T. Enclose a self-addressed, stamped, busness envelope. It would be a good dea to wrte "correctons" on a pece of paper and enclose t wth your mal. Otherwse, t mght get mxed n wth my contest for a free can of Florda ar. Test Your Electroncs Knowlexge A mxed bag By Sam Wlson Fgure 1. Result of a sawtooth waveform test performed on an amplfer. 1. In what feld of technology would you expect to fnd an "end effector?" 2. Regardng a SAW flter, what do the letters SAW stand for? 3. In what type of thyrstor crcut would you expect to fnd a snubber? 4. Whch of the followng statements s correct? A. When you stress a materal you get stran. B. When you stran a materal you get stress. 5. A Kelvn Brdge s used to measure A. capactance. B. nductance. C. resstance. D. frequency. 6. A techncan performs a sawtooth Wlson s the electroncs theory consultant for ES&T. Fgure 2. Dagram of a crcut. waveform test on an amplfer and gets the result shown n Fgure I. What does the result tell about the amplfer? 7. You can measure a voltage wth a A. varable capactor. B. gyrator. C. potentometer. D. None of these choces s correct. 8. A voltage doubler s connected to an ac power lne frequency of 60 Hz and an ac voltage of 120V. The output voltage should be n the range of A. 175V to 250V. B. 300V to 350V. C. 400V to 450V. D. None of these choces s correct. 9. What s the recprocal of reactance? 10. In the crcut of Fgure 2, what s the voltage between pont A and ground? (Answers on page 64) November 1995 Electronc Servcng & Technology 59

44 Computer Corner Is computer servce n your future? By Sheldon Fngerman Unfortunately, the cost of replacng many consumer electronc products s gettng about as nexpensve as servcng them. Ths fact has left many servcers scratchng ther heads wonderng about what the future wll brng. Obvously, the more expensve the product, the more nclned the consumer wll be to repar the tem rather than heavng the tem nto a dumpster and headng off to Wal-Mart. Computers easly ft nto the category of reparable tems...so far. The computer servce busness Ths magazne, as well as others, have had some excellent artcles dealng wth computer servcng. But, what they have not dealt wth are the realtes of actually beng n the busness, and whether beng n the computer servcng busness mght be a vable opton for you. There are many reasons computer servce s desrable: parts are relatvely easy to obtan. Hourly rates range from $60 to $90 per hour. The entre operaton can be carred out n your lvng room, (although you probably wouldn't want to). And n most cases, you can yank a part out of one brand name computer and stck t nto another of a dfferent brand. There s another sde to ths, however. If you are used to sttng at a bench, solvng problems at your own pace, computer servce defntely offers some surprses. Most repars are done on ste, wth a very nervous customer watchng your every move. Ths alone can be unnervng to the average bench techncan who, dur- Fngerman s an electronc, and computer con,ultzttu ttnd servcng techncan. ng a normal house call, may only have to deal wth a few kds wantng to know when the set wll be fxed. As rate as some customers can be wth regard to the speed at whch a televson s beng repared, ther busness s rarely brought to a halt because ther TV doesn't work. Techncan and customer communcaton To begn wth, the customer can be part of the problem. Many computer users know just enough to be dangerous, and t can be dffcult to get the proper nformaton n what I call the ntal "nterrogaton." They tend to be afrad to admt they may have done somethng wrong, even though the problem may merely have been a concdence rather than anythng they were dong at the tme of the falure. Gatherng as much nformaton as possble before startng a repar or consultaton, can save hours n the long run. It's mperatve that you fnd out what, f anythng, happened between the tme the computer was workng fne and the tme that t faled. A related problem s a lack of communcaton between the techncan and the customer. The customer may use terms that are n the techncan's computer vocabulary, but may actually mean somethng completely dfferent. If an offce has two computers lnked together, and the customer clams they want a new, larger hard drve nstalled n the "server," but they actually meant the "clent" computer, you may fnd yourself dong the same job twce. And who's fault s t? Maybe I'm wrong, but I tend to blame myself n these nstances. I'm supposed to be the expert here, and I've learned to ask the same questons more than once, pont to perpherals and say, "You mean that?," and draw a lot of pctures. Not unlke a customer who brngs n a TV wth nothng but a lne on the screen from left to rght. Yes, t s a "horzontal" lne, but you know the problem s actually n the vertcal crcut. The object s not to make the customer feel stupd, but to make sure your defntons are the same. Common problems A major headache for me, and a lot of other servcers as well, s tryng to fgure out whether a problem s hardware or software related. A serous knowledge of computer operatng systems, and lttle bt of knowledge about a lot of dfferent knds of software can help here, but there are so many new programs beng released all the tme-many full of "bugs" that mmc hardware problems-you mght fnd yourself jonng the Har Club For Men a lot sooner than you expected. Experence wll soon tell you whch software ttles tend to cause problems. And, beleve t or not, many software publshers wll confess pretty quckly when t s regardng a problem. I can't tell you how many tmes I've heard, "Oh yes. Gve us your address and we'll send out the 'latest' verson of the software." Another common problem s tryng to upgrade a system, only to fnd that the customer has no documentaton, the computer has no known brand name, and the motherboard has no dentfcaton of any knd. Usually, consumer electronc prod - 60 Electronc Servcng & Technology November 1995

45 ucts have some knd of label. A Sony s a Sony, and a JVC s a JVC. You need a part, you make a call. But what happens when the product has no dentfcaton and the customer wants to upgrade the RAM on her computer from 4 MBs to 8? Wll the computer accept a 4MB SIMM? If the computer has 8 SIMM slots, are they set up as two banks of 4 slots? Does each bank have to be flled completely? And wll the computer even accept the amount of RAM the customer wants? Most computers have a lmt as to how much upgradng can be done, and you would be surprsed at how lmted some of the older computers are. Keepng up wth what's new In the world of consumer electroncs t's mportant to keep up wth what's new. In most cases these changes have come n stages: transstors, ICs, surface mount components, stereo TV, etc. In the computer world, f you understand t, t's probably obsolete. And the ndustry won't gve us much of a break. I spend more tme readng now than I dd when I was n school. And, my malbox s flled every day wth more publcatons then Ed McMahon has down at The Publshers Clearng House. I have to read them all, or I wll fall behnd. Recently, magaznes lke PC Magazne have started releasng back ssues on CD- ROM. Ths has enabled me to purge some fles and free up space on my bookshelves. Ths new technology also makes searchng for artcles a snap. Magaznes lke ES&T also offer a wealth of tmely nformaton, but n the computer world thngs change very quckly. You probably have televson schematcs that are years old but get lots of use. Computer lterature that old makes good kndlng. Books make good reference materal, but by the tme they get the books publshed new products have already been ntroduced. Sometmes these products couldn't have even been magned by the books authors. It's pretty unnervng to see the latest copy of a book on DOS sttng on the shelf that reads, "Now ncludes DOS 6.0," when you know that Mcrosoft has already released DOS Tools and test equpment are always a concern when t comes to servcng new products, except when t comes to computer repar. Wth computer servce the most valuable tool you possess s rght between your ears. You'll fnd no matter how many peces of fancy test equpment you own, there s no substtute for good, sound logc; especally when dealng wth computers. To fx a computer, sometmes you have to thnk lke a computer. Takng ths to a Zen level, I guess you would have to "be" the computer. Tools Although a plethora of hand tools jammed n a custom case s always a luxury. and sometmes a necessty, a mnmum of hand tools are actually needed to servce most computers. An assortment of screwdrvers, basc hand tools, some specalty tools lke IC pullers, and lots of small screws and washers wll make up the bulk of your tool kt. In the vast majorty of repars, a pece of equpment, lke a scope would be excess baggage, but never leave your DMM behnd. THE FIRST, UNWRITTEN LAW OF VCR REPAIR The techncans at Howard Sams had your well-beng n mnd when they re -engneered VCRfacts to nclude mechancal algnment nformaton wth exact placement of gears and gear assembles. See how smple t can be! Pnch Cam (S) Pnch Speed Down Gear (64) GEAR ADJUSTMENTS ARE THE LEADING CAUSE OF INSANITY AND RAGE AMONG VCR SERVICE TECHNICIANS. To help n fndng the cure, call: Sub Cam Gear (112) Connecton Gear (65) Mode Swtch (55) In antcpaton of other common problems, VCRfacts also features consstent standard -notaton schematcs, electronc parts lsts, IC functons, nterconnect wrng dagrams, and extensve exploded vews. Now for your own peace of mnd, call us and order your subscrpton today. HOWARD W. SAMS & COMPANY 2647 Waterfront Parkway E. Dr., Indanapols, IN Crcle (68) on Reply Card 61

46 Dagnostc software s a necessty, and s readly avalable from many sources. You may have to experment wth a few to fnd the ones that work best for you. The latest versons of Mcrosoft DOS now nclude some dagnostc programs, and they're not bad. Dagnostc hardware s a luxury that's nce to have n your bag of trcks. To be honest, I haven't had a lot of experence wth dagnostc hardware, but many techncans swear by t. Replace modules Assumng the problem s hardware related, determnng whch part s defectve and smply replacng t s usually the best route to take. I know very few techncans who would attempt to repar an nternal modem that's "gone south," or open a hard drve wthout any nstructon. You should always look for problems a smple solder repar, or somethng smlar mght rectfy. I've actually come across a few poorly soldered power swtches. One of the few exceptons to smply replacng a component would be a "flaky" hard drve that just needs to be brought back from the dead. A lot of the dagnostc software that's avalable can actually "repar" hard drves that smply have defects n the magnetc materal whch store data, or may have shfted slghtly over tme causng what are called seek errors. Takng nto account the age of the drve, and the customer's needs, once the data has been resurrected t stll may be a good dea to transfer the data to a new hard drve. Remember, prces keep fallng whle relablty keeps mprovng. Havng an extra computer on hand can be an nvaluable dagnostc tool. And, as long as you are honest about sellng used parts, t's pretty easy to sell the parts off of your "test" computer, allowng you the luxury of upgradng that computer, whle gettng your customer back n the saddle quckly. Inventory Wth computer prces fallng all the tme, keepng a large nventory of parts can be a detrment. However, t's always a good dea to keep an assortment of common tems on hand. Wth everyone gettng on-lne these days, havng a few modems around couldn't hurt. But, you stll have to be careful. As wth other computer perpherals, a 2400 baud modem, that may have cost $250 when t was state of the art, may be worth almost nothng as your customers clamor for 14,400 and 28,800 baud modems, whch probably cost less now than that old 2400 baud modem you have sttng on your shelf. Unlke a TV, where you would smply replace a defectve part wth an exact replacement, many computer components can be easly upgraded to the latest technology by smply substtutng the part, lke the modem mentoned above. Other parts to keep on hand are adapters; lots of them. It's an awful feelng to get to a job wth a new CD-ROM drve, only to fnd that the computer's power supply doesn't have enough power cables. A smple Y adapter would have saved the day, f you had one. An extra keyboard s always a good tem to have around, but consderng the fact that you may only have a 50/50 chance the keyboard DIN plug wll ft the computer-there are two standards now -once agan an adapter can be a real tme saver. You can't have too many adapters. Profts and possbltes Another rarely thought of tool s a notebook computer. Even a relatvely nexpensve monochrome model has an external port that wll drve vrtually any color VGA montor well enough to evaluate. It's also a great place to store programs, tons of nformaton, a servce database, take lots of notes, and even contact bulletn boards and on-lne servces rght from the repar ste. Add a portable prnter and you can even crank out an nvoce on the spot. Not nexpensve, but f you use a lttle magnaton there are lots of possbltes here. Now, before you get too excted about all the bg bucks you are gong to make n ths busness, remember that good salares usually go hand and hand wth some degree of aggravaton. Recently, the communty I lve n started up a nonproft, low cost access to the Internet. I agreed to act as a volunteer "mentor." Soon, people who were havng problems gettng onlne were callng me at all hours. You'd thnk they were dallng 911. Many people called askng for "free" advce over the phone. I tend to be very lenent wth my tme when dealng wth establshed customers. Wth a prospectve clent you have to be a bt more careful. When workng n a consultng capacty all you have to sell s knowledge. How much of that you are wllng to gve away s up to you. So, how do you get started? If you've been mantanng your own computer(s), and/or been solvng some tough problems on other machnes, you mght want to dve rght n. If the "nnards" of a computer are new to you, see f there are any computer servce semnars n your area. You can always look under the hood of your own, but just knowng where all the parts are won't nearly be enough to start a computer servce busness. On the other hand, f you've been "surfng the Net" for years, one of the hottest professons rght now s gettng ndvduals and busnesses hooked up to the Internet. Except for nstallng a modem here and there, you may never have to touch a screwdrver or a DMM to make a very good lvng. Lablty One often overlooked ssue that deals wth any type of repar busness s that of lablty. When you remove a hard drve you could be holdng years worth of data n your hands. Even an electrostatc dscharge could brng a thrvng busness to a complete halt. Check wth your nsurance company, and always try to get the customer to do a complete backup of any valuable data before you show up. Be rght up front about the possblty of data loss and other problems that mght occur durng a repar, and put some type of dsclamer on your nvoce. In other words, cover yourself. In many ways, I'd rather be faced wth a tough computer problem than a "dog" of a VCR that's been sttng on my bench for a week. But that's me. If you feel profts slppng away as more and more consumer products become throw away tems, servcng computers could be just the boost your busness needs. And don't thnk you can't do t. Anyone possessng the sklls necessary to fx a televson or VCR certanly has what t takes to dagnose and repar a computer. 62 Electronc Servcng & Technology November 1995

47 Books Surface -Mount Technology for PC Boards, PROMPT Publcatons, 528 pages, llus., $26.95 SMT holds great promse for manufacturng technology, and the race to adopt t has been descrbed as the latest revoluton n electroncs. Surface -Mount Technology for PC Boards wll gve everyone from the engneer, to the nterested layman, the nsde track on ths pace -settng technology. Snce ts ntroducton, the largest roadblock from the complete acceptance and effcency of SMT has been a lack of communcaton. The how-to knowledge of SMT comes from the factory floor, but the exchange of deas and demands between the electroncs desgners and manufacturng personnel has been ether nonexstent or, at best, neffectve. Surface -Mount Technology forpc Boards provdes a twoway street for communcaton between the manufacturng technology and the layout consderatons for SMT. The subjects covered n the book nclude, benefts and lmtatons of SMT, surface -mount components, SMT manufacturng methods, practcal applcatons and standards, a glossary of SMT terms, and more. Prompt Publcatons, 2647 Waterfront Parkway E. Drve, Indanapols, IN Easy Laser Prnter Mantenance and Repar, Stephen J. Bgelow, Professonal Book Group, 224 pages, 200 llus, $28.95 hardcover, $18.95 paperback Laser and LED prnters have become ndspensable fxtures n most of today's offces and, lke other offce equpment that usually performs relably, are taken for granted- untl they break down. Easy Laser Prnter Mantenance and Repar s wrtten to address these problems. Wrtten especally for those wth modest techncal sklls, ths easy -to -use gude wll have readers handlng common problems such as poor mage qualty, paper jams, and msfeeds wth ease. Step-bystep nstructons and llustratons ad n solvng more complex problems too. And, just as mportant, ths book teaches how to extend a prnter's lfe by performng adjustments, cleanng, and other routne mantenance. Chapters are ncluded on, components, power supples, mage formaton systems, solderng and test nstruments, servce gudelnes and precautons, mechancal systems, electronc controls, and servce gudelnes. The book also ncludes an ndex of prnter manufacturers and supply sources and a "quck -reference" ndex of troubleshootng procedures. McGraw-Hll, Inc., Blue Rdge Summt, PA The Informaton Broker's Handbook, Sue Rugge and Alfred Glossbrenner, Professonal Book Group, 528 pages, $49.95 hardcover, $34.95 paperback. The frst edton of The Informaton Broker's Handbook was a bestseller. Co - wrtten by the woman who poneered the feld of nformaton brokerng and an expert n PC telecommuncatons and onlne servces, t helped launch the careers of thousands of nformaton professonals. Not content to rest on ther laurels, authors Sue Rugge and Alfred Glossbrenner now delver a completely up-to-date revson of ther masterwork wth new coverage of the Internet and ts enormous potental for nformaton -gatherng. There s also a new chapter on how to proft from the burgeonng feld of publc records -searchng, ncludng the authors' nsghtful tps on technques and markets. In addton, they nclude new or expanded coverage reflectng other advances n technology, ncludng the fastgrowng array of CD-ROM databases, modem and CD-ROM hardware, and database graphcal front-end software. All of the helpful nformaton from the frst edton s stll there too; how to handle the busness end, ncludng how to prce your nformaton brokerng servces, get more out of clents, project a strong mage, and more. Appendces provde resources and reference works, contact names and telephone numbers, as well as nformaton on how to beneft from the resources, expertse, and mentorng offered by the Assocaton of Independent Informaton Professonals (AIIP). McGraw-Hll, Inc., Blue Rdge Summt, PA Onlne Resources for Busness: Gettng the Informaton Your Busness Needs to Stay Compettve, By Alfred Glossbrenner & John Rosenberg, John Wley &Sons, Inc., 385 pages, $24.95 paperback Onlne Resources for Busness: Gettng the Informaton Your Busness Needs to Stay Compettve, descrbes today's onlne servce, the type of nformaton they provde, and how much t costs to obtan that nformaton. Wrtten by onlne experts Alfred Glossbrenner and John Rosenberg, ths compendum shows busnesses how to save tme and money when conductng research onlne. A complete revson of the 1987 bestseller, How to Look t up Onlne, Onlne Resources for Busness, provdes the key to usng the two general types of onlne servces: Busness Servces: Lexs/Nexs (Law), Dow Jones (Fnancal), DIALOG (Corporate),Consumer Servces such as Internet, CompuServe, Amerca Onlne, Prodgy, access to dozens of lttle-known nformaton sources, lke marketng studes and government statstcs, sophstcated search strateges, tools, and technques, nformaton on thrd -party research frms, rates for accessng, downloadng, and prntng nformaton from onlne searches. John Wley & Sons, Inc., 605 Thrd Avenue, New York, NY PSMA Standardzed Handbook of Termnology for the Power Sources Industry, Power Source Manufacturers Assocaton, $35.00 The second edton of the PSMA Standardzed Handbook of Termnology for the Power Sources Industry has been publshed by the Power Sources Manufacturers Assocaton and s avalable to power professonals Ths "dctonary" of defntons has been updated and expanded from an orgnal verson produced eght years ago. It addresses new state-of-the-art actvtes, long-establshed technology and regulatory ssues. The new edton was edted by Joe Stockert of The NJ Power Group, Morrstown, NJ, and revewed by 18 power electroncs specalsts from the PSMA and the IEEE Power Electroncs Socety. The handbook ncludes defntons and explanatons of more than 700 terms n the power ndustry, along wth nformaton on testng and standards agences, nternatonal power components standards and publcatons, world voltages and frequences, mltary specfcatons, standards and handbooks. "It s ntrgung," Stockert sad, "to see how much has changed n the last eght years and how much has stayed the same. The nfluence of new global technologes November 1995 Electronc Servcng & Technology 63

48 Test Your Electroncs Knowledge Answers to the quz (from page 59) 1. Robotcs-t s the grpper at the end of a robotc arm that enables the robot to pck thngs up. 2. Surface Acoustc Wave-the flter acts by sendng acoustc waves across the surface of a pezoelectrc materal. 3. An SCR crcut-the snubber prevents undesred turn -on. 4. A - Stran (deformaton) s the result of stress (force). 5. C - It measures very low resstance values. 6. The amplfer has a poor hgh -frequency response. It cannot follow the rapd change from hgh to low ampltude. 7. C - There are two meanngs to the word potentometer. It s a varable resstor, and, t s a specal nstrument for measurng voltage. 8. B - The peak voltage s 120V X = about 170V. The doubler multples that value (approxmately) by 22 X 170V = 340V 9. Susceptance-susceptance s a measure of the ease wth whch an ac current can pass through a reactance. 10. The same amount of current flows through Ra and Rb so the voltage across Ra equals the voltage across R2. The total drop across the two resstors s 18V, so, there must be 9V drop across each resstor. Usng conventonal current flow and gong clockwse from x to y: +6-9 = -3V (answer). As a double check, gong counterclockwse from x to y: 12+9 = -3V (answer). and marketng programs have revsed power capabltes and strateges and the new edton reflects these developments." PSMA, 3685 Motor Ave., Los Angeles, CA Introducton to Mcroprocessor Theory &Operaton,ByJ.A.SamWlson & Joseph Rsse, PROMPT Publcatons, 232pp, llus., $16.95 paperback PROMPT Publcatons announces the release of Introducton to Mcroprocessor Theory & Operaton-a book that explores the mcroprocessor. Ths book explans how mcroprocessors work wth ther assocated crcutry to provde basc core energy to the entre system. Snce the ntroducton of mcroprocessor theory, a great gap has exsted between ts prncples of operaton and those attrbuted to the more unversally accepted deas revealed n dgtal electroncs theory. The authors set out to elmnate the myths and nform the reader on the crcuts, specfcatons, and general ns -and -outs of mcroprocessor systems. Subjects covered n Introducton to Mcroprocessor Theory & Operaton nclude, features of the Mcroprocessor, basc Mcroprocessor systems, ALU, mass memores, bnary components, and transducers as data sources. PROMPT Publcatons, Howard W. Sams & Company, Indanapols, IN Gecks' Engneerng Formulas Released on CD-ROM, By Kurt and Rener Geck, McGraw-Hll, Inc., $79.95 CD-ROM, $89.95 dskette McGraw-Hll announces the electronc edton of the classc Engneerng Formulas, 6th Edton by Kurt and Rener Geck. The Electronc Geck's Engneerng Formulas s a CD-ROM that uses the techncal data and mathematcal formulas from the Geck's Engneerng Formulas to generate nstant solutons for engneerng and scentfc equatons. The best-sellng Geck's - frst publshed n 1967 and now n ts sxth edton - s an nvaluable resource of fundamental formulas and data for engneers. Wth a fully nteractve nterface powered by MathSoft, Inc.'s MathCad engne, the new Electronc Geck's s a complete engneerng reference that solves the most tme-consumng techncal calculatons nstantly. Indspensable for engneers, engneerng students, and other professonals, the Electronc Geck's provdes powerful navgatonal tools for full -text searchng. It allows access to nformaton through multple paths, ncludng the table of contents, ndex, and hypertext lnkng. In addton, nteractve math allows the user to perform calculatons and test results wth dfferent nput varables. Wth over 500 lve formulas and more than 400 graphc mages, the Electronc Gecks' provdes nstant problem solvng for, electrcal engneerng, areas, dynamcs, machne parts, strength, sold bodes, radaton physcs, statcs, hydraulcs, knematcs, heat, and producton engneerng. The Electronc Gecks' Engneerng Formulas s a tme -savng tool that smplfes all knds of techncal calculatons, from smple geometry to radaton physcs. McGraw-Hll, Inc., 11 West 19th Street, New York, NY Troubleshootng and Reparng Computer Montors, Stephen J. Bgelow, Professonal Book Group, 320 pages, 150 llus., $36.95 hardcover Wth the enormous varety of montor confguratons on the market today, the tme s rpe for a comprehensve gude to the essental dagnostc and repar tools and technques. That's exactly what Troubleshootng and Reparng Computer Montors delvers. Electroncs techncans and ntermedate to advanced -level hobbysts who want to take advantage of the ever-expandng market for montor repar techncans wll need the crtcal nformaton presented n ths authortatve, A -to -Z gude. Readers wll learn how to tackle vrtually any montor problem wth ether CRT -based montors or the growng number of LCD varetes. After begnnng wth an overvew of concepts, components, technologes, and test equpment, author Stephen J. Bgelow presents detals about: CRT algnment and degaussng, specfcatons and archtectures of monochrome, CGA, EGA, and VGA montors, state-of-the-art plasma dsplays, lnear, swtchng, and hgh -voltage power supples, logc and drvers supportng both CRT and LCD montors, major graphcs standards used n today's montors, and many other mportant topcs. McGraw-Hll, Inc., Blue Rdge Summt, PA Electronc Servcng & Technology November 1995

49 Products Fber optc tool Fotec has ntroduced a new, nexpensve tool that smplfes fber optc network nstallaton and troubleshootng. The FOtracer s a vsble lght source that makes t possble to vsually test fber optc cables for contnuty and trace fbers throughout the network. Most connecton problems n fber optc networks can be dagnosed wth a vsual check of contnuty. A vsble lght source s needed for vsual testng, snce the actual network sources are n the nfrared regon and are nvsble. The tracer can test multmode cables up to 4 km (2.5 mles) long, makng t useful for all fber optc LAN applcatons. Crcle (100) on Reply Card VCR nstructonal cassette An nstructonal vdeocassette from Electronx presents practcal repar technques for servcng the G Chasss VCR. The G Chasss s found n most VCRs manufactured from 1992 to the present. It s a much smaller chasss, whch n turn allows the physcal sze of the VCR to be dramatcally reduced. Along wth ths reducton comes a varety of new servcng problems, especally ones whch nvolve algnment between the top and bottom of the chasss. These algnments can be a nghtmare for someone not famlar wth the proper methods and procedures to perform them. A Lay - person's Gude to G Chasss VCR Repar wll take the fear out of servcng the G Chasss. The vdeo dsplays many common falures of the chasss and easy ways to repar them. Crcle (101) on Reply Card Telephone transfer unt Electronc Desgn Specalsts ntroduces a product that wll allow callers to get hold of a person easer, whle smultaneously elmnatng unnecessary calls and wasted cellular tme. There s only one phone number requred for contactng the owner of the cellular phone. The selectve teletransfer unt (STU) connects to an offce or home phone lne and answerng machne, and wll selectvely transfer the caller by ther command to a cellphone, or pager, or voce mal, or any other number, or by your command, can tell callers to leave a message on the answerng machne. The level and ablty to transfer can be made from anywhere by smply callng STU and enterng the proper functons. Because cellular or pager phone numbers are programmed nto STU, they reman secret. STU combnes the features of "call forwardng," "no -answer transfer," and "ProLnk," and adds the ablty to flter the caller selectvty nstead of smply transferrng everythng. Crcle (102) on Reply Card Curve tracer Hameg Instruments, Inc. ntroduces the HM8042 Curve Tracer. Ths s a module that plugs nto the company's HM Manframe Power Supply and s used n conjuncton wth any osclloscope that has X -Y dsplay capabltes. It can test dodes, transstors, FETs and thyrstors. The nstrument s mcroprocessor based, has a well desgned front panel and measures and dsplays characterstc curves of semconductor devces. Dgtzed data s used to generate a 5 -curve, flcker -free X -Y osclloscope dsplay. A 4 -dgt LED numerc readout ndcates parametrc data. On -screen cursors defne the curve areas of nterest and the nternal processor calculates dynamc "h" parameters. Sngle measurement data can be stored for a match of two devces or as a test reference. Crcle (103) on Reply Card Tmer/counter Fluke Corporaton announces two new addtons to the PM 6680 famly of tmer/ counter/analyzers. The new PM 6681 tnner/counter has a hgh tme-nterva resoluton of 50ps sngle -shot and 1 ps averaged, plus a speed of up to 8000 measurements per second. Ths allows the unt to make unversal tmer/counter measurements, such as tme nterval, frequency, phase and jtter, at accuraces hgher than currently possble. Also avalable from Fluke s the PM B, whch s an mproved verson of the PM 6680 nstrument. The products have bult-n hardware features for fast data capture. When the tmer/counters are lnked to a PC runnng the TmeVew software package, they are turned nto hghly accurate modulaton doman analyzers. TmeVew handles tme and frequency analyss and advanced statstcal and FFT processng. These capabltes gve users extra facltes, such as analyzng frequency stablty, and revealng and qualfyng sgnal anomales (jtter, nose or modulaton artfacts, for example) that would otherwse reman hdden. Other examples nclude analyzng frequency modulaton, locatng hdden nose sources, plottng frequency agle sgnal sources (frequency vs. tme), analyzng VCO transent response and vewng frequency locked loop dynamcs. Crcle (104) on Reply Card Removal Kt Premum Parts+ offers the Chp Quk Removal Kt, whch contans a specal alloy solder, lqud flux, solder removal brad, and complete nstructons. The removal process s smple. The only tools requred are a solderng ron and a dental pck. The techncan apples specal lqud flux to all leads of the SMD to be removed. Then, wth a solderng ron, melts the specal alloy solder unformly on all pns. The ron temperature recommended s just over 200F. The ron s used to keep the specal alloy solder n a molten state long enough to react wth November 1995 Electronc Servcng & Technology 65

50 the exstng solder. Now the SMD can easly be lfted from the board wth a puller or dental pck. To clean the PC board, the techncan uses a cotton -tpped swab dpped n flux and a solderng ron to push large globs to an unused secton of the board where t s left to soldfy and be removed. Solder brad and flux can be used for any addtonal clean up that may be needed. Crcle (105) on Reply Card 71/4/1 A-1 Test accessores kt ITT Pomona Electroncs' new Model 6003 Electroncs Lab Test Kt s an all - n -one combnaton of the most popular test accessores used n the laboratory. It s a versatle kt for users of dgtal mult - meters and osclloscopes. The kt contans a combnaton of features and accessores for specfc test requrements, ncludng operator -safe nsulaton, nterchangeable test ponts, and nterfaces. The 6003 ncludes a x 1 - x10 osclloscope probe, an assortment of nterchangeable tps, handy leads and clps, BNC female -to -double banana plug adapter, as well as a mult -use DMM test lead wth accessores for testng ICs, board and components crcutry. Crcle (106) on Reply Card Montor dagnostc and vdeo dsplay utltes Tech Assst, Inc. s shppng Dsplay Mate Professonal wth DsplayMate for Wndows. Ths s the leadng utlty for montor and vdeo board servce, mantenance and/or repar. The utltes allow the user to use the setup dsplay test seres to properly adjust the user controls. The user can measure the resoluton, test and measure the color regstraton and/or color convergence error and measure the geometrc dstorton. In the testng features, you can perform any or all 300 tests to determne f the vdeo system s workng properly. It can generate more than 200 test patterns and determne the strengths, weaknesses, qualty, performance, and compatblty of all vdeo system hardware. In the compatblty secton, DsplayMate Professonal wll use vdeo adapter BIOS functon and regster, to probe for hdden flaws and lmtatons n the hardware. Another feature s the speed performance testng. Ths wll report on the performance of the vdeo accelerator. The user may also wrte scrpts to customze the testng to ther preferred routnes and when fnshed, prnt a report for ther clent of all testng completed and the results. Crcle (107) on Reply Card Credt card sze DMM Wavetek Corporaton announces a new DMM, the DM78A. The shrt pocket sze makes the meter easy to use and carry. The multmeter comes n a vnyl carryng case, wth test leads and probes attached. The credt-card szed DMM offers a 3200 count dsplay wth a 32 segment baragraph, useful for measurng peakng and nullng crcuts and locatng bad dodes, and features a Data Hold, whch freezes a readng on the dsplay for later evaluaton, and provdes safer operaton when n a dangerous area. Auto Shut-off, s desgned to UL and EN (IEC) Agency Safety standards. Crcle (108) on Reply Card Electrcal cleaner and degreaser CRC Industres announces a new formula for ts Lectra Clean electrcal cleaner and degreaser. Absent n the new formula, n order to meet Clean Ar Act standards, s the prmary ngredent 1, 1, 1 Trchlorethane. The new formulaton contans no CFCs, 1, 1, 1-Trchlorethane, or Perchlorethylene, but accordng to the company has retaned all of ts desrable characterstcs ncludng non -flammablty, non - corrosveness and freedom from resdue. The product can be used n a wde varety of electrcal applcatons to ncrease the lfe and effcency of motors, parts, relays, swtches and other equpment by effectvely removng grease, ol, drt and sludge. Crcle (109) on Reply Card SMD tool kt Automated Producton Equpment's SMD Tool Kt contans all of the components necessary to quckly 1.cm:we and replace Ball Grd Arrays and all surface mounted components or prnted crcut boards, when used wth the SMD Electronc Servcng & Technology November 1995

51 Sound Systems for Your Automoble The How-to Gude for Audo Systems Selecton and Installaton By Alvs J. Evans and Erc J. Evans Ths book wll show you how to plan your car stereo system, choose components and speakers and nstall and nterconnect them to acheve the best sound qualty possble. Order# $ IC Cross Reference Book By Howard W. Sams & Company The IC Cross Reference Book, compled from manufacturers' data and from the analyss of consumer electroncs devces for Photofact servce data, wll help you fnd replacements or substtutons for more than 35,000 ICs or modules.order# $ INOUSTRIAI1 ELECTRONICS W" O Ele TECINICIANS.4 vs, 8.wN 19 q Industral Electroncs for Techncans By J.A. Sam Wlson and Joseph Rsse Industral Electroncs for Techncans provdes an overvew of the topcs covered n the Industral Electroncs for Techncans CET test, and s also a valuable reference on ndustral electroncs n general. Orcer# IET $ Advanced Electronc Projects for Your Home and Automoble By Stephen Kamchk You w I gan valuable experence In the Feld of advanced electroncs by learnng b buld the nterestng and useful projects featured n Advanced Electronc Projects. Order# $ Introducton to Mcroprocessor Theory and Operaton A Self -Study Gude wth Experments By J.A. Sam Wlson and Joseph Rsse Introducton to Mcroprocessor Theory and Operaton takes you nto the heart of computerzed equpment and reveals how mcroprocessors work. Order# $ Securty Systems for Your -come and Automoble By Gordon McComb In smple, easy - to -understand language, Securty Systems for Your Home and Automoble tells you everythng you need to know to select and nstall a securty system wth a mnmum of tools. Order# $ Speakers for Your Home and Automoble How to Buld a Qualty Audo System By Gordon McComb, Alvs J. Evans and Erc J. Evans Buld qualty home speaker systems that wll complement the sound avalable from your other components usng the nstructons n ths book. Order# SPEAKERS orol--; $ Basc Prncples of Semconductors By Irvng M. Gottleb Wth ts smplfed explanatons and thorough dscussons. Basc Prncples of Semconductors provdes everyone, from the hobbyst and student rght up to the techncan and professonal electrcan, wth an excellent ntroducton and reference nto the prncples of semconductors. Order# Basc Prncples of Semconductor, MOM P1 If1.11:0NDIC70R : : F.I91NC ,74/5." Semconductor Cross Reference Book By Howard W. Sams & Company From the makers of Photofact servce documentaton, the Semconductor Cross Reference Book s the most comprehensve gude to replacement data for all major types of semconductors. Ths volume contans over 475,000 part numbers and other dentfyng numbers. Order# $ Tube Substtuton G ade Complete Gude to Replacements for Vacuum Tubes and Pcture Tubes By Wllam Smth and Barry Buchanan The Tube Substtuton Handbook wll help antque rado buffs, consumer electroncs techncans and other nterested ndvduals fnd the rght rep'acement tube when servcng older electroncs products. Order# $ Electronc Control Projects for the Hobbyst and Techncan By Henry C. Smth and Crag B. Foster Electronc Control Projects for the Hobbyst and Techncan helps the reader know how and why an electronc crcut works, then apples that knowledge to buldng practcal and dependable projects that solve real, everyday problems. Order# $ Schematc Dagrams Schematc The Bascs of Interpretaton and Use Dagrams By J. Rchard Johnson Step-by-step, Schematc Dagrams shows you how to recognze schematc symbols and ther uses and functons n dagrams, and to nterpret dagrams so you can desgn, mantan and repar electronc equpment. Order# $ AYES! I want to learn from the experts. Rush me my book(s) rght away! Please add $4 shppng & handlng. FREE shppng & handlng for orders $50 and over. Please make your check or money order payable to: Electronc Servcng & Technology. L1Order Toll -Free Qty Order# Descrpton Prce Total Prce Ncme Acdress Shppng/Handlng (New York Resdents add applcable sales tax) Total Cty_ State Zp MC/NASA/AMEX/Dscover # Expres Form of payment: CI MC 0 VISA 0 AMEX Dscover Check 0 Money Order L Please mal your orders to: Electronc Servcng & lechnology, 76 North Broadway, Hcksvlle, New York FAX j

52 Chpmaster. The Chpmaster s a hot ar - based complete communcatons rework and repar staton for rework and repar of pagers, 2 -way rados, cellular telephone electroncs, and other communcatons equpment. The SMD Tool Kt contans an SMD pad prep cleaner that gently removes oxdaton and contamnaton to restore pads to optmum solderablty. The cleaner removes the coatng from the pager or crcut and s non-toxc to workers. The kt also contans an assortment of dental - qualty probe tools, "no -clean" solderng flux, syrnges for flux applcaton BGA "no -clean" removal prep soluton, a vacuum handlng tool, a wck gun for wckng away old solder, assorted dspensng needles for the syrnges, and tweezers. Crcle (111) on Reply Card e :60P -4.!ItCrof tze, DMM Feldpece Instruments has ntroduced the LT6 handheld dgtal multmeter. It measures volts, ohms, amps, ndcates contnuty wth a beep, and tests power semconductors for catastrophc falure. The meter works wth all the accessory heads and other accessores offered by the manufacturer for ther Heavy Duty lne of meters. The optonal deluxe test leads (model ADL2) ft the LT6 and can be used to connect the accessory heads to the meter. Currently avalable accessory heads nclude converters for current, MA relatve humdty, and dual temperature. Crcle (110) on Reply Card Current probe Fluke Corporaton, ntroduces ts new 80q -110s probe, whch offers hgh -accuracy current measurements for a wde range of osclloscope and multmeter applcatons. The new probe s compatble wth other of the company's products. -- The probe accurately reproduces current waveforms as they occur. Users smply connect the clamp to a waveform recordng devce to clearly vew dstorted waveforms that result from nonlnear loads, such as computers, adjustable speed motor drves, and electronc ballasts for fluorescent lghtng. Crcle (112) on Reply Card Crcut software Interactve Image Technologes Ltd., announces the Electroncs Workbench Engneer's Pack. Ths pack offers desgn engneers the ablty to desgn and verfy complex crcuts usng the company's mxed -mode smulaton and then ntegrate these crcuts nto SPICE and PCB desgn automaton software-speedng up the entre desgn process. The product comes wth over 2,450 models, whch allow users to desgn more complex crcuts. The models correspond to actual parts that users would select from popular databooks. The models are made of four specalzed lbrary sets: 500 Transstors, 600 FETs, 500 Dodes and Thyrstors, and 500 Opamps. Crcle (113) on Reply Card Swvelng robotcs Robotc machnes from Inca Corporaton can move TVs, vdeo dsplays, projectors or computers n every drecton. They are avalable n four standard models for lftng loads of 100 to 450 pounds. Modular panel movers can move up to 250 pound panels 3 feet wde. All are equpped to take a rado remote or swtch controller and can be fxed to work wth a pullout and swvel as well. Crcle (114) on Reply Card Hand tools Cooper Tools offers a premum lne of cutters and plers under the Erem name desgned for those who specalze n state-of-the-art technology. Each tool s machne process made from hgh-grade tool steel and s selectvely heat treated at cuttng edges. A precson double -screw jont system prevents lateral blade movement. Other features nclude lead catchers, ant -glare fnsh, serrated tps, and conductve molded grps. Ergonomcally desgned grps are also avalable. Crcle (115) on Reply Card Rework system Amercan Hakko, Inc. ntroduces The Model 702 Rework System; a fully ntegrated rework system for all PCB repars. Ths new system ncorporates the latest desgns wth a straght handle desolderng tool, a medum style solderng ron, an extra slm style solderng ron, and a complete hot ar SMD rework staton. The Model 702 ncorporates an ESD desgn for statc free performance and safety. Calbraton can be performed n house, and ts compact desgn uses a mnmum of bench space. Crcle (116) on Reply Card Alternate source drectory Hearst Busness Publshng/UTP Dvson announces release of the 1995 IC Master Alternate Source Drectory (ICMASD) on floppy dsk. Ths electronc verson of the Alternate Source Drectory from the IC Master catalog s an ndustry wde cross-reference lstng of 127,000 current and dscontnued devces. It ncludes complete manufacturer contact nformaton. The all -new 1995 ICMASD has been enhanced wth the addton of devce category nformaton such as Lnear -Telecommuncatons, or Memory - EPROM. A new, more powerful nterface makes accessng the expanded and enhanced data faster and more effcent. ICMASD cuts hours of searchng for functonal equvalents and second sources. Crcle (117) on Reply Card 68 Electronc Servcng & Technology November 1995

53 Classfed Classfed advertsng s avalable by the word or per column nch. By -the word. $1.65 per word, per nserton, pre -pad Mnmum charge s $35 per nserton. Intals and abbrevatons count as full words. Indcate free category headng (For Sale, Busness Opportuntes. Mscellaneous, Wanted). Blnd ads (reples sent to ES&T for forwardng) are $40 addtonal. No agency dscounts are allowed for classfed advertsng by the word. Contact Krste Wckham at to place your classfed ad (by -the -word). Mastercard, VISA, Amercan Express and Dscover are accepted for FAX or mal orders. Per column Inch (classfed Dsplay): $235 per column nch, per nserton, wth frequency dscounts avalable, 1" mnmum, blled at 1/4" ncrements after that 10" maxmum per ad. Blnd ads are $40 addton. Reader Servce Number $25 addtonal to cover processng and handlng costs. (Free to 4 -nch or larger ads.) For more nformaton regardng classfed dsplay advertsng please call Optonal color (determned by magazne) $150 addtonal per nserton. Send your order, materals and payments to: Electronc Servcng & Technology, 76 North Broadway, Hcksvlle, New York Attn: Classfed Department Phone: FAX: FOR SALE 'BULLETIN IT'S OFFICIAL -THE LARGEST TIP DATBASE 'OVER 17,300' VALUABLE, TIME -SAVING REPAIRS for servcng TV's, VCR's, Projecton TV's, CAMCORDERS & other electroncs, organzed n an easy -to -use computer program-the TIP REPAIR Program. PROFES- SIONAL BOARD/COMPONENT LEVEL REPAIRS from Techncans lke yourself. ADD your own tps. PRINT tps. BACKUP & save the tps that you have Added/Revsed. Owners of our COMPUTERIZED TIP PRO- GRAM say ths s the **BEST** techncal tp program on the market today. Works on ANY IBM compatble computer. NEW VERSION-works n DOS and WINDOWS. Only $ and WO' COPY PROTECTION!!! > Don't be fooled by other cheaper tp programs.> that are copy protected wth lmted nstalls (now that's a gmmck) and stll other programs that are more expensve wth less tps & a database that never gets any bgger >. FREE shppng for Prepad orders (U.S.A.) **FREE** Demo! Have your own tps? Ask about our TIP EXCHANGE polcy wth FREE Updates! CALL / HIGHER INTELLI- GENCE SOFTWARE, 60 Farmngton Lane, Melvlle, NY ((24,000)) THE WORLDS LARGEST TECH -TIP PROGRAM IN THE USA. "NEVER BEFORE HAS THERE BEEN AN OFFER LIKE THIS" PROOF 1S IN OUR PRODUCT - TEST OUR FULL PROGRAM. WWWWWWWWW"FREE" "FREE" "FREE" MD))))))))))))))))))))))) We are so sure you wll fnd our computer tech -tp program to be THE BEST OFFERED ANYWHERE, that we wll shp our ENTIRE PRO- GRAM at NO COST TO YOU. Test 1 week, f you are dssatsfed, smply return the program Postage Pad - there s absolutely NO RISK OR COST TO YOU. "OUR TRUST IS IN YOUR SATISFACTION" (Proven to pay for tself wthn a few repars) FEATURES INCLUDE: FCC -ID cross reference manual cover ng VCR's & Mcrowave, Product Processng Forms. Repars 1977 :hru Nov. 1995, TV, VCR, CD, LD, Projecton, Montor, Stereo, Camcorder, Amplfer, Combo Unts, Fax Machne, Satellte, & Mcrowave. SEMI- ANNUAL NEWSLETTER wth Step -By -Step Repars usng today's technques. NEW product nformaton, ndustry News and Servce Center Assstance. WE ARE THE ONLY TECH -TIP COMPANY that publshes our ENTIRE PROGRAM IN PAPER MANUALS, for servce centers who are not computerzed. "FREE" format changes computer or paper at each update. One-tme membershp "PAYS." OUR MEM- BERS RECEIVED ((10,000)) NEW TECH -TIPS "FREE" IN OUR NOV. 95 UPDATE. To those Computerzed, we offer the MOST AD- VANCED DOS or TRUE WINDOWS SYSTEM, n whch you may Enter or Prnt Out repars. Our program covers repars, 165 BRANDS ALL IN ONE CONVENIENT PROGRAM. Repars are collected daly at three major servce centers and sent weekly to our Data Center where each Tech -Tp s gone over completely. Addtonal Lookup and Cross Reference nformaton s added. Ths process s how we constantly IMPROVE and INCREASE the program FOR YOUR BENEFIT at each UPDATE. SAVE TIME DIAGNOSING, ORDERING SERVICE MANU- ALS and RESESEARCHING PARTS NUMBERS YOU MAY NOT NEED! GET TO THE BOTTOM LINE "PROFITABILITY," and CALL Ed Erckson, NESDA Member and Presdent of (TV -Man Tech -Tps, Inc.) YOU'LL BE GLAD YOU DID! (800) (407) EST. FOR SALE SERVICE TIPS NOW CONTAINS OVER 17,250 TECHNICAL TIPS. Due to the TREMENDOUS RESPONSE FROM OUR CUSTOMERS, SERVICE TIPS IS NOW ONE OF THE LARGEST AND MOST CUR- RENT DATABASE'S AVAILABLE TODAY. SERVICE TIPS s organzed n ALPHABETICAL ORDER by Brand Model/Chasss & Symptom wth 3 lnes for Symptom and 8 for Soluton. YOU CAN REVISE and EDIT or PRINT any servce tp n our database, AND YOU CAN ADD YOUR OWN INFORMATION and t wll automatcally be alphabe:zed and sorted. SERVICE TIPS HAS MULTIPLE WAYS TO BACKUP ALL OR PART OF THE DATA. The program contans ACTU- AL TECHNICIANS FINDINGS on TV's, Projecton TV's, VCR's, Camcorders and other consumer electronc equpment. UNLIKE SOME OTHER PROGRAMS, WE HAVE NO GIMMICKS. ATTENTION ALL 1ST TIME BUYERS - CALL US FOR A SPECIAL BONUS OFFER. SERVICE TIPS s avalable for $ plus s&h. For more nformaton CALL US at (from US & Canada). Demo Dsk and Quarterly Updates avalable.** DON'T BE LEFT OUT EVEN IF YOU DON'T OWN A COMPUTER ** ELECTRONIC SOFTWARE DEVEL- OPERS NOW OFFERS 1,926 SERVICE TIPS IN BOOK FORM COV- ERING COLOR & PROJECTION TV'S, AND VCR'S FOR EMERSON, GOLDSTAR, NEC, SAMSUNG AND ZENITH FOR THE LOW PRICE of $ TO ORDER Mal Check or Money Order for $59.95 to: ELEC- TRONIC SOFTWARE DEVELOPERS INC. 826 SO MAIN ST, SOUTH FARMINGDALE, NY or call TV CASE HISTORIES: Booklet wth 2,440+ hstores. Satsfacton assured. Only $49 (plus $3.00 for prorty mal). Mke's Repar Servce, P.O. Box 217, Aberdeen Provng Ground, MD Same malng address 31 years. Send SASE for samples , FIX TVS 11am-9pm. TEST EQUIPMENT BOUGHT & SOLD: OSCILLOSCOPES, ETC FAX FREE 9-516/517 MODULE CURE!!! Stop replacng! Repar easly yourself. Send busness SASE: TEK Enterprses, 212 Marabou Drve, Newark, DE SERVICE DATA & HARD TO FIND PARTS prevously -owned SAMs, manufacturers data, books, FREE catalog. AG Tannenbaum, Box 386, Ambler, PA 19002, (215) , fax (215) We re -cone all speakers. Dealer servce our specalty. Free prce lst. Daphragms, parts, refoam kts and more! Tr-State Loudspeaker, **** SONY TUNER CURE **** /-12 Stop replacng! Repar easly yourself & save! Senc $15.00: TEK Enterprses, 212 Marabou Drve, Newark, DE FURTHER PRICE REDUCTION. Dehl Mark III $49, Dehl Mark V Horzontal crcut tester $169. New. Conductve coatng for remote control keypads $9.99 ppd. WEEC, 2411 Nob Hll Road, Madson, WI (608) , (608) FREE ZENITH CURES Earn $$$ Repar Zenth TV modules found n over 1000 models, Symcure manual shows you how. $89.95 or send SASE for FREE samples. ZMEX, 807 Queen Palm Lane, Sarasota, FL November 1995 Electronc Servcng & Technology 69

54 FOR SALE Sencore equpment (all models). Please call for a complete lst. Tech Choce Dstrbutng, Lance, ELECTRONICS SOFTWARE DEVELOPERS ANNOUNCES THE RELEASE OF ITS LATEST COMPUTER PROGRAMmun FCC and MODEL to MODEL CROSS REFERENCE PROGRAM - t wll enable you to cross reference 94 Brands wth over 3,000 models and over 200 FCC numbers. Ths NEW program s easy -to- use and all nformaton s n alpha -numercal order and covers VCR's, Camcorders, TV's, and Computer Montors. Compled from techncans' nformaton, our easy - to -use format wll SAVE YOU TIME AND MONEY as well as ELIMI- NATING UNNECESSARY PARTS COSTS and DUPLICATE SER- VICE LITERATURE. To order send check or money order for $39.95 plus $3.50 shppng and handlng to Electronc Software Developers Inc 826 S. Man St., S. Farmngdale, NY OR for Credt Card Orders CALL DON'T HAVE A COMPUTER - ths nformaton s also avalable n book form for $49.95 plus $3.50 shppng and handlng. Sencore test equpment, LC101, PA81, PR57, SC3100, SG80, TVA92, VC93, VG91. Fnancng avalable, wll sell ndvdually, prces negotable. DC&H, PO Box 0475, Rockledge, FL , / FOR SALE "Servce Shop Invoce Database" for Wndows. Prepare customer nvoces wth ease. Mouse orented wth dropdown boxes, pushbuttons, checkboxes, and more. Select parts, prces, names, labor, status, all wth the mouse. Fast, accurate, tme saver. Saves, Adds, Prnts, Searches all records. "SHOP TESTED." Personalzed prnted nvoce. Techncan compatble. Satsfacton guaranteed. $ Phllps Software & Computer, call for demo Sencore VG91 vdeo generator, TVA92 TV analyzer, and VC93 VCR analyzer. All less than one year old. Transferable lfetme replacement guarantee. Must sell! Cash or take over payments. Contact Chrs, 4026 Mornngsde Drve, Bloomngton, IN 47408, , To Advertse n Electronc Servcng & Technology's Classfed Secton Call Readers' Exchange Readers' Exchange s a free servce. The followng restrctons apply to Readers' Exchange: Only ndvdual readers may use Readers' Exchange, and tems must be restrcted to those that are ordnarly assocated wth consumer electroncs as a busness or hobby. If you're n busness to sell the tem(s) you want to offer for sale, the approprate place for your message s n a pad advertsement, not Readers' Exchange. Readers' Exchange tems must be restrcted to no more than three tems each for wanted and for sale, and may be no more than approxmately four magazne column lnes n length (about 20 words). All submssons must be typed or prnted clearly! Send your Readers' Exchange submssons to: Readers' Exchange Electronc Servcng & Technology, 76 N. Broadway,Hcksvlle, NY FOR SALE Photofacts from 1980, '83, and '84. Call wth best offer. Contact: Dana, , early mornng or Wed. and Thurs. evenngs after 6 P.M. Sencore equpment, PR57, CR70, TVA92, VC93, VG91. Complete wth modules and manuals, $ total package, lke new. Contact: Sencore VC93 VCR analyzer. Two years old. hardly used. All accessores and orgnal box, $ Contact: , after 6 PM EST. Ask for Barry. Closed my shop. Wll completely outft shop. Sencore: SC6 I, DM56A, ST66, CR70, PR57. B&K 1250 NTSC, 1601 power supply, 520B transstor tester, 820 capactor tester, 1822 counter. Have other tems. Best offer. Contact: V. Knght, anytme, or fax Sencore CM2000, SC61, PA81, PR57. All orgnal boxes, cables, probes, adapters, and manuals. Excellent condton, $ Separate prces avalable. Contact: Mke, Sencore VA62, $850.00, SC61 $ or both for $ All leads n excellent condton. Contact: NRI VCR tranng vdeotapes, $ MT1 Moble Rado tranng course, 40 lessons, $ Contact: BJ. Jett, Farmers Telephone Cooperatve, PO Box 217, Ransvlle, AL 35986, x 203. Sencore equpment lke new. SC3100, VG91/TVA92, CR70. Gong out of busness. All for $ , or best offer.contact: Sams Photofacts, 1275 folders, numbered 205 through Wll sell for $250.00, or sell n small lots for $.75 per folder plus shppng. Send SASE for lstng. Contact: Wlly at Sencore VA62 and VC63, $ Marcon 2018 syntheszed frequency generator 80 KHz to 520 MHz, $ Tektronx 475 scope 200MHz wth probes, $ Leader LCG 396, NTSC generator, $ Contact: Alex Torok, Weller solderng statons EC2001 ESD, $150.00, EC2000 ESD $ Both lke new. Ungar 4624 solder/desolder, $400 new. Plus more, just ask. Contact: Jmmy Sencore VG91 and TVA92. Lke new, all manuals, cables and boxes, $ or take over payments (contract). Also a PR -57 solaton unt $350.00, osclloscope 20 MHz B&K model 4667 pcture tube checker and rev, $ Plus more. Wll pay shppng. Contact: Gordon E. Lane, 239 Jacksonan Drve, Hermtage, TN 37076, Sencore VC93 VCR analyzer, excellent condton, $ Contact: I en, Len's VCR & L' ectroncs Repar, Electronc Servcng & Technology November 1995

55 FOR SALE Hckok sgnal generator 615. Jackson cathode ray osclloscope, CR03. Sencore color generator, G141. Contact: Ann Bchanch, 15 1/2 West Lake Street, Chsholm, MN 55719, SC61 - less than 500 hours. Used once snce Sencore calbrated t. Comes wth 2 drect probes, probes, and hgh voltage probe, $ Contact: , leave message or call after 6 PM EST. Sencore VA62, NT64, VC63, excellent condton, wth probes and manuals n orgnal box $ , shppng ncluded. Contact: Keth Conroy, Woods Road, Utca,NY 13502, Tenma, 60 MHz osclloscope 3 channel, 8 trace, $600.00, or best offer. Contact: Mchael, , AM's. Sencore 100 MHz waveform and crcut analyzer, model SC3I00. Purchased n New, excellent condton, cart ncluded, $ Contact: Route 2 Box 232D, Wllston, SC 29853, ext.365. Smpson 380M mcrowave leakage tester, $400.00, 260-6xlm-analog tester $ B&K 467 CRT tester, $ Excellent condton, com- Vtaly, Tenma montor tester, lke new. Lst for $ n MCM's Catalog. I need to get $ for t. Contact: RFM Sales & Servce, , fax Partal set of Sams Photofacts,#800-#2000. Some mssng, $ Contact: (days) (evenngs). ask for Glora. Hckok tube tester, model 532 dynamc mutual conductance, electronc volt -ohm -capacty mllameter, model 203. Phlco, dynamc tester, model Contact: Ed H. Rauchfuss, 946 Santa Clara Place, Los Alamos, NM , New Sencore VG91 vdeo generator and VC93 VCR analyzer, n orgnal cartons, never turned on. $3, frm. Contact: Bob, Howard W. Sams Photofacts from early 1940 to Make an offer. Contact: Fredde, Sencore, Tentel, Fluke, Tektronx, Phlps, Heath test equpment, offce equpment, parts, and more. Retred from busness. SASE. Contact: Bob Kovalesk, 55 Edgewood Avenue, Clfton, NJ Tenma 20 MHz osclloscope, dual trace wth probes, $ Fluke 83 DMM wth leads, $ B&K CRT analyzer model 480 wth many adapters, $ Contact: Bruce, Lke new Sencore test equpment SC60 dual trace scope, FC51 1 GHz counter, PR57 Isol transformer, DVM 56 multmeter, and more. Cost mnus 70% OBO. Also, CATV taps, spltters, Jerrold SJ5 2W amp, WWV recever FM mod, connectors. Contact: Superor varable transformer, 0-135Vac, 7Amp $ Heathkt IG-57A, RF/IF sweep generator, $ Contact: Walt, WANTED Man power transformer and schematc for Rock-Ola Juke Box, model #452 seral # Contact: J. Harrs, 76 Lllan, Yorkvlle, IL RCA stereo recever MSR 140, tuner pack assembly, part # Contact: Rchard Zabel!, ext. 105, daytme. Sanyo JV688 stereo ntegrated amplfer, need servce manual or schematc. Wll pay for copy or wll copy and return. Contact: George Columbo, 4185 Lousana St. #3, San Dego, CA 92104, , or corn. New A.A or qualty rebult A. Sony 470DLB22 pcture tube. Contact: Ron' s Electronc Servce. 345 Hgh Avenue. Jefferson, IN, Htach flyback, , or model CK-200 (GTX chasss) wth good flyback. Contact: Garbs Saatjan, 5612 Marburn Ave., Los Angeles, CA JVC model RX-9 computer controlled recever, need access to servce manual. JVC advses manual no longer avalable. Wll pay for loan or copy, (your terms), postage and phone call. Contact: Charles W. Morgan, 646 Devon Drve, Nashvlle, TN , Panasonc C-2600 satellte recever n good workng condton. Contact: Ron Tsubota, 130 Douglas Road, Ontaro, OR 97914, Good used CRTS - 510YT-B22A, CPJ 370 BV B&K TV-TC. Contact: Samuel Pearlman, 7513 E. Camno De Querab, Tucson, AZ Shell/cartrdge mount dual turntable model 128. ZB-17 EVG replacement. Contact: Dan Palmer, 3438 Alvn Krby Rd., Tmmonsvlle, SC 29161, Splsbury SBX-11A and Marcon CP24, CP34 HF SSB rados for pans, SMATV Modulators and sngle channel bandpass flters, #20 stranded Teflon wre, Motorola HT software. Contact: Rejean Matheu, rd Avenue, Val D' or, Quebec J9P 4N7, , fax Sylvana CK3000 test jg or hgh voltage focus dvder for ths jg. State prce. Contact: Happy Valley 7V, 501 Rossevelt Street. Exeter, PA Toshba type - channel selector swtch (Sears - part # ) for model # Fche vewer/projector Mcro -Corp model #760 or any make of fche vewer. Contact: M. Fscher, 2947 N. Spruce Road, Pulask, WI 54162, (after 8P.M. central tme zone). Sencore test equpment of all types. Wll pay cash for qualty test equpment. Must be n good condton. Contact: Lance, ScTech SEG-21 need servce manual or schematc. Magnavox AR9160BK specal effects generator/genlock system. Contact: Jack, 5262 US RT. 50, Fayettevlle, OH 45118, RCA CTC 72N, model ET396W, need VHF tuner KRK 199. Contact: George T. Fogelman, 1201 Idlewlde, El Paso, TX 79925, Techncs power unt model SH- 10E for a Techncs drect drve turntable model SPIO MKII. The manufacturer clamed ths to be a dscontnued 1978 model. Contact: McDonald Pnder, Ext Multtech model MP -020 VHS vdeocassette player, servce nformaton needed. Contact: T. Gratkowsk, 5 Gross Lane, Easthampton, MA 01027, SAVE TIME For fast, accurate servce, please remove the peel off label used to address your magazne, and attach t to the Reader Servce Card, the Address Change Card or to any correspondence you send us regardng your subscrpton. Mal All Correspondence To: Electronc Servcng & Technology 76 North Broadway Hcksvlle, NY November 1995 Electronc Servcng & Technology 71

56 "Sperry Tech's, Prcng Gude", Updated new 6th edton a framework for settng rates that apply to H -Tech products..a formula that guarantees SUCCESS' "Call Toll Free for detals Advertser's Index Company Reader Page Servce Advertser Number Number Hotlne Crcle (62) on Reply Card TUBES TUBES -TUBES VISA onty $99" World's Largest Range Over 2,000 Types, Domestc & Foregn UP TO 85% OFF pf,t`,, Internatonal Components Corporaton Toll Free N Y State Maxess Road. Melvlle. New York Crcle (58) on Reply Card The FAX DOCTOR - Snce 1988 the FAX,(1;;48041 DOCTOR has compled a Tek Tp Manual coverng well over 500 common problems for all makes and models of FAX machnes. ' Call now to order your copy Crcle (57) on Reply Card NEW AUTO RADIO VIBRATORS PLUS: 6 to 12 VOLT POWER INVERTERS, SPEAKERS. TRANSFORMERS, DIAL GLASS, MORE! It you repar older car rados...you NEED OUR FREE CATALOG! ANTIQUE AUTOMOBILE RADIO INC. 700 Tampa Rd., Palm Harbor, FL (800) WE FIX AM or FAX (813) Crcle (53) on Reply Card GEne The most fun you can have wth your rado on! No other onlne servce serves the rado hobbyst lke GEne's Rado & Electroncs RoundTable does. Scannng, shortwave, ham rado, even an onlne callsgn database so you can look up QSL nfo n an nstant! And we have t all at one of the lowest connect tme rates of all the major onlne servces To sgn up for GEne wth your computer & modem, dal toll free n the U.S. or Canada At the U#= prompt, type JOINGENIE And for a specal ntroductory offer, At the key/offer code prompt type BWH528 Crcle (77) on Reply Card 72 Electronc Servcng & Technology November 1995 Amercan Hakko Andrews Electroncs Antque Automoble Rado /88 HAKKO / /WE FIX AM Automated Productons Equpment / B & K Precson IFC Chemtroncs / Computer & Montor Mantenance / Dalban Corporaton / Den -On Instruments, Inc / FAX DOCTOR, The / Fluke Corporaton BC /44 -FLUKE GEne Rado& Elec. Roundtable / ISCET / Internatonal Components Corp / NESDA 13,27 800/ PTS Electroncs / Parts Express / Premum Parts / Sams, Howard & Company / Satellte Dealers Assocaton / Sencore IBC 1 800/SENCORE Sperry Tech / Stoner, Inc / Tech Assst / Trtroncs / WAHL CLIPPER CORPORATION / Xytronc /HOT WAND We'd lke to see your company lsted here too. Call Dane Klusner at 516/ to work out an advertsng program talored to sut your needs. SALES OFFICE PHONE (516) FAX (516) Porer mport sm ear ofc lochnology "

57 Techncal know-how s a servce techncan's most mportant tool. Today more than ever, a sold functonal understandng, combned wth proven effectve troubleshootng technques s essental to your success. But where do you get sold, well-rounded tranng? How do you learn good troubleshootng sklls? To meet the growng demand for sold, fundamental, practcal tranng, Sencore ntroduces Tech Tranng - tranng by techncans... for techncans. Computer Montor Servcng Course - TC100 (Approved for CEU credt) Ths hands-on self study course teaches you how to effcently test and troubleshoot as you work through the actvtes and self tests. You'll learn: How to quckly determne montor types How to make all montors look alke from the SMPS to the CRT What vdeo patterns to use to accurately dentfy falures Computer Montor Servcng Class - TC 100T (Approved for CEU credt) Ths 3 1/2 day class provdes hands-on experence on actual chasss. You'll learn how computer montors work, typcal crcut operaton, how to make adjustments, and lots of practcal troubleshootng. Call for locatons and dates. Understandng Televson Horzontal Stages - I'V300 The horzontal stages are the most complex, hardest workng, and probably the hghest falure part of a televson recever. Knowng how these stages work, how they fal, and how they nteract wth other crcuts wll help you conquer these dffcult servcng problems. Ths tranng package ncludes a self -study workbook and a 45 mnute vdeo. Tech Choce Techncal Troubleshootng Demonstratons Do you need a quck servcng refresher? No matter how you servce, you'll take home valuable tps that you'll put nto practce mmedately. Choose from these practcal demonstratons: Computer Montor Troubleshootng Proftable TV Troubleshootng Smplfed VCR Servcng Camera/Camcorder Testng & Troubleshootng Check the cty lstng below for upcomng Tech Tranng locatons: Albuquerque Atlanta Baltmore Brmngham (AL) Boston Buffalo Calgary Chcago Cncnnat Cleveland Dallas Detrot Edmonton El Paso Houston Indanapols Kansas Cty Knoxvlle (TN) Los Angeles Mam New York Cty Oklahoma Cty Phladelpha Phoenx Pttsburgh Ralegh (NC) Reno San Dego Seattle Soux Falls Tampa Toronto Vancouver (Tentatve lst. Not all Tech Tranng classes wll he held n all locatons. Call for detals.) Crcle (1) on Reply Card Call SENCORE( ) Sencore, 3200 Sencore Drve, Soux Falls, SD Phone: (605) FAX (605)

58 True-rms. True values. Do you troubleshoot non-lnear crcuts or loads? If so, you need true-rms capablty to ensure accurate measurements. Now you can get ths capablty wthout havng to compromse on qualty or safety to stay wthn your budget. Prced at just $199.00*, the new Fluke Model 76 true-rms DMM s the latest n the long lne of trje-rms values from Fluke. You can use the Model 76 to easly measure true-rms ac current and volts, dc current and volts, ohms, capactance, contnuty, and frequency. And, the Model 76 s the only DMM n ts class that meets UL, CE, CSA, and TO/ certfcaton standards and conforms to the IEC product safety stancard for Overvoltage Category 111.(1) You'll fnd that knd of true value all the way down the lne wth Fluke test tools. See your local Fluke dstrbutor to select a true-rms meter that fts whatever your job or budget demands =1... Fluke 32 $149* Fluke 33 $269* Fluke 76 Fluke 87 Fluke 8060A $199* $3350 $4590 EUV GS U S Its! prce Prces subject to change wthout nonce (I) Approvals/Lstng pendant Crcle (11) on Reply Card ISG Fluke Corporaton P 0. Box 9090, WS 250E, Everett. WA USA U.S. (206) Canada (905) Europe (31 40) Other countres (206) All rghts reserved. Ad no FLUKE

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