SERVICE MANUAL MODEL : VM-1201 REVISION : A0 DATE : MAY DOCUMENT NUMBER :

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1 SERVICE MANUAL MODEL : VM-0 REVISION : A0 DATE : MAY.. 00 DOCUMENT NUMBER :

2 WARNING ========== For continuous protection against radiation, shock and flame, replace only with same type and rating components specified in the approved sheets. Disclaimer Speco Technologies makes no representation or warranties, either expressed or implied, with respect to the contents hereof and specifically disclaims any warranties, merchantability or fitness for any particular purpose. Furthermore Speco Technologies reserves the right to revise this publication and to make changes from time to time in contents hereof without obligation to notify any person of such revision or changes. Table of Contents. INTRODUCTION OPERATIONAL SPECIFICATION Operating Environment Signal Input Requirements Power Input Requirements FUNCTIONAL SPECIFICATION Display Quality CONTROL AND ADJUSTMENTS PHYSICAL SPECIFICATIONS THEORY OF OPERATION MAIN POWER SUPPLY BLOCK VIDEO INPUT BLOCK Video filter.... VERTICAL & HORIZONTAL PROCESSOR.. Vertical guard.. Vertical Drive Output..... Sync Separator... Phase Detector.... Supply Horizontal Oscillator, Horizontal O/P Transistor and Second Phase Detector 8.. Mute Output And 0/0 HZ Identification Sandcastle Output. 8

3 . VERTICAL DEFLECTION BLOCK HORIZONTAL DEFLECTION BLOCK TROUBLESHOOTING INSTRUCTIONS NO DISPLAY, NO POWER NO DISPLAY, (POWER OK) NO DISPLAY, (NO ASTER) NO PICTURE OR NO COLOR (RASTERK) VERTICAL DEFLECTION FAILURE APPENDIX: A. SPARE PARTS LIST B. SCHEMATICS AND PCB LAYOUT DIAGRAM

4 Audience This service manual is primarily for system / service engineers, distributors and dealers. It carries the assumption that the reader understands the basic operating concepts. Purpose This manual contains reference data for Speco Technologies monitor. It gives information regarding the operating principles of monitors, as well as technical service and maintenance information.. Introduction The VM-0, high performance monochrome monitor, display over,000 TV lines resolution on a bright -inch picture tube. This combination provides excellent multi-screen displays commonly produced by picture-in picture and quad units. All user controls are conveniently located behind a protective front panel door. This monitor can be placed on a desk or mounted in a standard -inch rack (with an optional rack mount kit) This series are housed in an enameled steel cabinet for ruggedness and durability, and with the exception of the picture tube, the circuitry is all solid-state. It also feature video loop through connectors with switchable high-z/ohm termination. The VM-0 is an excellent choice when you require a rugged, compact B/W monitor. The exquisite and reliable design of this monitor will provide years of trouble-free operation.. Operational Specification.. Operating Environment Temperature Operating :-0 to + 0 Storage :-0 to +0 Humidity (Relative) Operating :0 to 8% non-condensing Storage :0 to 9% non-condensing

5 .. Signal Input Requirements Connector For CVBS:BNC terminal Type:composite video input Level:.0Vp-p Synchronous:0. V Luminance:0.V Polarity:Positive bright Impedance: ohms.. Power Input Requirements Operating Voltage Range:90 ~ V AC at 0 / 0 ±Hz Input Current at 90 V AC Operating:0. Amps rms. maximum Input Current at V Operating:0. Amps rms. maximum Power consumption Normal operation:0 Watts maximum. Functional Specification The standard conditions for verifying the following specification are as below:

6 Temperature : ± Magnetic field :No additional magnetic field in near side AC line Input :00 ~ 0 V AC ±0%, 0/0 ±Hz Warm-up Time :0 minutes min. after power on and signal applied Ambient light :00 to 00 lux... Display Quality Display area (monoscope pattern):full scan Video Amplifier Performance Video Bandwidth :8 MHz Light output (brightness and contrast at maximum) At block pattern :00 FL minimum At full white pattern :0 FL minimum Contrast adjustment range:over db Linearity (cross pattern) Horizontal :0% maximum Vertical :0% maximum

7 Picture geometry:.% Picture centering: mm Size stability:picture luminance from FL to max., the size shall be less than.% (with full white pattern) Swing and jitters:swing and jitters are not allowed (viewed at 0cm from eyes to screen). Focus:(viewed at 0cm from eye to screen, contrast adjusted to set luminance at 0 FL with full white pattern, brightness set at raster just disappeared) Inspect full character pattern, all characters should be distinguished.. Controls and adjustments External user s controls: Brightness adjustment Contrast adjustment Horizontal hold Vertical hold Volume adjustment (optional).. Physical Specifications Dimension:mm(H) 0mm(W) x00mm(d) Net Weight:9 Kg. Theory of Operation

8 This section describes each functional block of the monitor.. Main Power Supply Block AC power input:ac socket Line input noise / EMI filtering:line filter T90 ; X-Cap C90, C90. Y-Cap C90, C90, C90. Over current protection:fuse Power on/off control:power switch AC to DC conversion and filtering:diode D90, Capacitor C90 Start-up circuit:r9, C9. Main switching power controller, free run oscillation, voltage feed back, switching duty control, cycle by cycle over current protection, power MOSFET driving:u90-uc8 Free run oscillation:r909, C90. Voltage feed back and control:output voltage control R90, R9 & VR90; gain compensation C9& R90. Current sensing and cycle by cycle over current protection:current sensing R90; Noise filtering R90, C909. Energy storing and transferring:power transformer T90. Power driving:power MOS transistor Q90.

9 Snubber circuit:snubber C90, D90, R90. Primary side self-powering circuit:d90,c9. Output. volts for vertical & horizontal drive circuits:d90, C9. Output.volts for horizontal deflection circuit:d90,c9.. Video input block Signal input buffering and switch CVBS Input buffer :Q0 & R0,R0. Video filter & output stage. Video input:through C0 to W0 (Contrast VR ) and differential amplifier Q0, Q0. Video amplifier: Cascade amplifier R9, Q0, Q0, R, C0. Brightness control:vr0, R, R, R, Q0.. Vertical & horizontal processor.. Vertical guard: This vertical feedback signal on pin when the level on pin is below 0.v or high than.8v the guide circuit inserts a continuous level of.v in the sandcastle output signal of pin.the results in the blanking of the picture displayed, thus preventing a burnt-in horizontal line... Vertical drive output: The drive o/p pin of U0 delivers a drive current of.ma at V output through R0 to U0 pin... Sync separator: The video input through C0, R0 and filter C0 to pin of U0.The Sync separator is designed such that the slicing level is independent of the amplitude of the Sync pulse. The 8

10 black level is stored at pin by C0. The slicing level is stored at pin by C0 and decided by R0... Phase detector: The phase detector circuit is connected to pin8. The circuits are activated depending on the voltage of pin8 and the state of the Sync pulse noise detection circuit, C0, C0, R0... Supply (pin9, 0 and ): U0 can start operating by application of a very low supply current into pin. When the starting circuit is taken from pin0 via internal diode, and the voltage on pin will stabilize to a typical value of 9.V.. Horizontal oscillator, horizontal output transistor, and second phase detector (pin,, and): The oscillator is connected to pin. An external RC; C09, R, VR0; sets the frequency combination between pin and ground. The open collect horizontal output is connected to pin. The duty factor is set by an internal npn emitter follower stage connected to pin. When no flyback pulse is detected at pin the duty factor of the horizontal output stage is set to 0%... Mute output and 0/0HZ identification (pin): Pin has the possibility for 0/0HZ identification. A pull-high resistor R08 achieves the function...8 Sandcastle output (pin): The sandcastle output pulse generated at pin.. Vertical Deflection Block Power amplifier: The DC level across C08 and the current is detected by R0 and feedback to U0 through R. The driver output comes from pin and it drives the yoke by a negatives slope current ramp R9 is used to stabilize the power amplifier. Boost power D0, C0 is connected to pin. 9

11 Flyback generator: U0 pin is the output of the flyback generator that when driven, jumps from low to high condition C0 transfers the jump to pin Vertical size control:vr0, R, R08.. Horizontal Deflection Block Horizontal drive buffering:driving source-u0 pin. Driving transistor-q0, to pull high the driving waveform to drive the Q0(MOS FET). Horizontal deflection:horizontal Output transistor-q0; Load-Yoke inductance and C ; D0, High Voltage generation-flyback transformer. Troubleshooting Instructions This chapter describes possible failures of the monitor with corresponding check/correction actions, and guidelines for safe operation and service of the monitor.. No Display, No Power.. First of all, turn power off, use multimeter to check Q90, and R90, replace if bad. Turn power on after that... Check DC voltage across C90. If no voltage or voltage too low, check and fix the following components:ac receptacle poor contact, fuse F0 broken, power switch malfunction, or bridge diode D90 bad.. Check voltage on U90 pin for start up condition:if voltage on U90 pin reaches the start up voltage(around to.v), U90 UC8 will start to work and output V at pin 8. If voltage on U0 pin is too low, check and fix following circuits:start up circuit R9, and C9... If no output pulses at U90 pin, check and replace U90. 0

12 .. If driving pulses at U90 pin and drain of Q90 are correct but voltage at U90 pin low than threshold voltage --causing U90 to stop and restart periodically, check and repair following circuits. Power transformer T90 bad; D90 short-circuit/opened.. No Display, power output normal... Check and fix FBT B+:If no B+(.V)on pin of FBT replace D90, C9... Check driving output voltage:0 or very low check and replace Q0, Q0... Power off monitor. Check yoke connection. Use multimeter to check D0, D0, D0, Fix if any is bad... Power on, check voltage at pin0 of U0 if no voltage, check and fix Vertical circuit B+, D90.. No Display (No Raster)... Check yoke connection... Check CRT board and verify CRT heater is on... Check G voltage if fail, check and fix FBT or D0... Check K (cathode) voltage at negative of D0 about 0V, If no voltage output Check and replace D0 and C0.. Vertical Deflection Failure.. Vertical display can't be held--check and fix:u0... Vertical raster abnormal (one horizontal line, size too small or fold back on top / bottom) -- check and fix:v supply at U0 pin, if has voltage check and fix U0.

13 Appendix A. Spare Parts List Location Parts Number Description F Fuse, A/0V, slow blow D Diode A, 00V, RS0 D Diode,.A, 800V, BA9 D0, D Diode, A, 800V, FR0 D90, D90, D Diode, FR00 D90, D Diode, A, 00V, FR0 Q Power MOS SK99 Q0, Q0, Q0, Q0, Q Transistor NPN SC8 Q Transistor NPN SC88 Q Transistor PNP SA0 Q0, Q Transistor NPN SD U IC TDA9B U IC TEA8 U IC UC8 FBT Flyback Transformer T Driver Transformer T Driver Transformer R J CR K W R *9J CF 0.9 W R J MOF 8K W

14 Appendix B. Schematics and PCB Layout Diagram. Schematics Page -- Main Board, Video Board.. Schematics Page Power Supply, Video Amplifier. PCB Layout -- Video Board, Circuit Trace. PCB Layout -- Main Board, Silk Screen

15 D C B A W0 R 0K CRT BOARD C0 U/00V VR0 MB R 80K Title Number Revision Size B Date: Sheet of File: D C B A G G G PLUG AC SOCKET W90 F90.A/0V C90.U/0V T90 EE- C9 EC 00U/V C90 0.U/0V R90 0K C90 /00V C90 /00V D90 A/00V C90 U/00V C9 EC 00U/V D90 FR0 R9 8K W R90 K W C90.0 KV D90 BA9 T90 8 ERL- D90 HER0 D90 FR0 C9 000U/V C9 EC 00U/0V.V L90 UH V.V R9 0 W.9V W0 B+.9V R K R 0K C U/V Q0 SC88 C U/V R 8.K W R.K /W OPTION S0 SPARK GAP K R. /W HGND HEAT J0 CRT SOCKET D90 FR0 C98 EC 000U/0V GND VC U90 COMP IC8 Vfb OUT Ise R90 8 D90 N8 R90 K G C908 /KV 8 Vref Rt/Ct S D R90 K C9 PEI 0 VR90 SVR KB R9.9K R90 M C9 0/0V R909 K C P Q90 SK99 R90.9 OPTION W0(PIN)W0(PIN) GND VIN CONT VR BOARD FUNCTION V-POSI H-POSI SYNC+ SYNC- R90 90 C90 /00V R908 POWER BOARD VR0 00 R 00 R K VR8 K R.K R8 0 VR0 K R 0 R K VR0 K VM-90B/0/0B POWER/B CRT/B VR/B

16 8 A B C D 8 D C B A Title Number Revision Size Date: File: Drawn By: U0 TDA9 C 0 R K R0.K R0 8K R 80 Q0 SC8 R K C0 00U/V R8 Q0 IRF0 R08 K C08 U R K C0. C09 00P R 0K VR0 H-HOLD R09 0 C U/0V R.K R0.K C0 C09.U R 0 R 0K R08 00 R0. W VR0 00B V-SIZE R C0. 8 U0 IC TDA8 R0.K R0.K C0.0 C0.0 R0 K C0 00U/V D0 N00 R. W.9V C0 00P C0 0 R0 R0 80 /W C.0 C0 0P R0 80 R0.K C0 0P C0 U/V R0 C0.U C0.U C0.U R0.K C08 000U/V.8 W R0 W0 VIDEO IN R8 K C0 U/V Q0 SC8 R0 0 R0 K R0 K C0 0U/V 8 W0 Q0 SC8 R9 0 C0 C0P 00V R0.K Q0 SC9 R.K R.8K R K Q0 SA R.8K R 0K D0 N8 W0 V R0 K R.K Q0 SC8 Q0 SC8 R 80 R09 0 R08 0 C0.U/0V R0 0 R0 K R0.K C0 U/V 0U/VC0 VR0 0K BRIGHT Q0 SC8 R0.K R8.8K C08.U R K C /00V D0 FR0 R0 8. W W0 DY W0 D0 FR0 D0 FR0 C0 0U/0V C0 /0V L0 C0 0U/0V H.V L0 UH.9V 8 C? FBT- B+.V J? 8/W 8 U0 LM8 C0 0U/V R0 0 C0 R0 W C0 000U/V V C0 00U/V W0 W0 VR? 0KB C0 R0 8.K C0 U/V R0 0K VM-90B/0/0B W/AUDIO MAIN BOARD

Synchronization circuit with synchronized vertical divider system for 60 Hz TDA2579C

Synchronization circuit with synchronized vertical divider system for 60 Hz TDA2579C FEATURES Synchronization and horizontal part Horizontal sync separator and noise inverter Horizontal oscillator Horizontal output stage Horizontal phase detector (sync to oscillator) Triple current source