INSTRUCTION MANUAL MODEL IEC-788 NTSC/PAL, F1/F2, S-VHS CLOSED CAPTION DECODER LINK ELECTRONICS, INC. 2137 Rust Avenue Cape Girardeau, Missouri 63703 Phone: 573-334-4433 Fax: 573-334-9255 e-mail: sales @ linkelectronics.com website: www.linkelectronics.com
TABLE OF CONTENTS GENERAL DESCRIPTION... Page 2 SPECIFICATIONS... Page 3 SETUP PROCEDURE... Pages 4-5 TECHNICAL DESCRIPTION... Pages 6-7 PRODUCT WARRANTY... Page 8 SERVICE INFORMATION... Page 8 PARTS LAYOUT... Page 9 FRONT/REAR PANEL/RACK TRAY... Page 10 1
IEC-788 GENERAL DESCRIPTION The IEC-788 is a high-performance Closed Caption Decoder for the NTSC and PAL systems. It is capable of processing and displaying all standard closed caption format trandsmissions, including EIA-608 Extended Character Set. This includes up to 64 additional characters to permit correct typography in Spanish, French,, and other European languages. In addition, accents above capital letters, as well as, descenders of lower case letters are supported. Nine standard data channels are supported by the IEC-788: Captions channels 1 thru 4 (CC1-CC4), Text channels 1 thru 4 (T1-T4) and Extended Data Services (XDS). The various decoding channels are selectable from four front-panel toggle switches. A single rear-panel toggle switch provides NTSC/PAL video standard selection. Designed with the professional user in mind, the IEC-788 processes baseband video in either composite or S-Video formats. A rear-panel push-button switch is used to select the input/output format. The composite video format uses a single high impedance looping input with two outputs. The S-Video format can use standard 4-pin mini-din connectors or BNCs for its input/output. The video performance is outstanding with differential phase and gain errors limited to less than 0.1 and 0.1% respectively. The un-weighted signal-to-noise ration approaches 70dB. AC-Coupled, complementary differential input amplifiers assure high common-mode noise rejection, while discrete phase-linear keyers provide clean insertion of the decoded characters into the video image. For added flexibility, the AC mains selection is available at the front-panel as well. Packaged in LINK s compact 700 Series chassis, the IEC-788 is both rugged and reliable. If desired, it may be rack-mounted along side two other 700 Series units of any mix. In addition, the IEC-788 is backed by LINK s standard ten-year warranty. High performance, flexibility, and economy are equally represented in the IEC-788 Closed Caption Decoder. 2
IEC-788 SPECIFICATIONS COMPOSITE INPUT: Video Level:... 1.0Vpp ±6dB Impedance:... >18kS Looping Connector:... BNC Maximum DC on Inputs:... ±6.0VDC Common Mode Range:... 5Vpp CMRR @60Hz:... >50dB COMPOSITE OUTPUTS: Number:... Two Connector:... BNC Level:... Unity Gain Character Video:... 90 IRE Units Character Background:... 10 IRE Units Impedance:... 75S ±1% Frequency Response:... ±0.1dB at 15MHz... -0.5dB at 17MHz... -1.0dB at 18.5MHz... -3.0dB at 26MHz Differential Gain:... 0.10% Differential Phase:... 0.10 Propagation Delay:...19nS ±3ns Hum and Noise:... >60dB to 5 MHz... >40dB above 5MHz DC Offset:... <2mV, Clamped Line Rate Tilt:... <0.1% Field Rate Tilt:... <0.1% S-VIDEO INPUT: Y Level:... 1 Vpp ±6dB C Level:... 0.6 Vpp Nominal Impedance:... 75S ±1% Connector:... Four Pin Mini Din S-VIDEO OUTPUT: Number:... Two, one 4 Pin Mini Din & One BNC pair (Y & C) Y Level:... 1 Vpp ±6dB C Level:... 0.6 Vpp Nominal ENVIRONMENTAL: Temperature:...0 to 50 C ambient Humidity:... 10%/90% non-condensing Power:...9.5 VAR AC Voltage:... 120/240 VAC±10%, 50/60Hz MECHANICAL: Height:... 1.0 inches Width:... 5.5 inches Depth:... 9.25 inches Weight:... 2lbs., 9oz. 3
IEC-788 SET-UP PROCEDURE NOTE: THIS UNIT WAS COMPLETELY CALIBRATED BEFORE IT WAS SHIPPED. USE THIS FACTORY SETUP PROCEDURE ONLY IF NEEDED! 1. Mid-range all pots. AC line switch to 115V. Pre-set front panel switches to OFF, mode = CAPTIONS, channel = 1, field = 1. Pre-set rear panel NTSC/PAL switch to NTSC. Set the rear panel Composite/S-Video switch to Composite. 2. Apply a 1Vpp NTSC color bar signal to the IEC-788 input BNC and terminate. Connect the IEC-788 video output to the video test system. (This system should consist of a wave-form monitor, vectorscope, video monitor, and oscilloscope with feed-thru termination.) 3. Apply power to the unit and note the AC line current: should be less than 200mA. 4. Adjust R43 to set the output video baseline DC level to ground (0Vdc). Adjust R50 to set the output video level to 1Vpp (unity gain). 5. Apply an NTSC video signal to the IEC-788 that is known to contain closed caption data encoded on line 21. This may be the output of a closed caption encoder, a demodulated off-air signal, or a video tape machine output. Select decoder ON at the front panel and select the appropriate data channel (usually CC1) to produce decoded captions at the video output. Adjust R40 to set the character background to 10IRE units. Next, adjust R66 to set the peak character luminance to 90IRE units. 6. Set the rear panel Composite/S-Video switch to S-Video. Connect an S-Video signal (Y/C) to the 4-pin mini-din input connector. Connect the Y/C output signal to the video test system. 7. Adjust R202 to set the output chroma level for unity gain. Adjust R94 to set the chroma baseline DC level to ground (0Vdc). Adjust R95 to set the insert balance (i.e. character background) to ground (0Vdc). 8. Note: Subsequent testing may be conducted in either Composite or S-Video mode. Check the operation of the front panel switches: Decoder Off/XDS/On, Captions and Text in both data channels and both fields should operate properly. 4
IEC-788 SETUP PROCEDURE (CON T) 9. Remove AC power from the unit and set the rear panel NTSC/PAL switch to PAL. Connect a PAL video signal to the IEC-788 that is known to contain closed caption data encoded on line 22. Again, this may be the output of a closed caption encoder, a demodulated off-air signal, or a video tape machine output. 10. Set the front panel AC line switch to 230V and connect the IEC-788 to an appropriate AC source. Apply power to the unit and confirm accurate decoding of the encoded caption data. This concludes the set-up of the IEC-788. 5
IEC-788 TECHNICAL DESCRIPTION Video input may be either Composite or S-Video. Switch SW123 selects between the two input modes, providing two 75S input terminations (by R199 and R200) if S-Video is selected. Input connectors are J122 and J123 (BNC) or J126 (4-pin mini-din). Likewise, SW123 controls the output connections to the appropriate BNCs (J124 and J125) and the 4-pin mini-din (J127). There are two basically identical video signal paths in the IEC-788 one for luminance/composite video and one for chrominance. Since they are so similar, only the luminance/composite video path will be described in detail. Incoming video is AC coupled via C1 and C2 into the complementary differential input cell consisting of transistors Q1 and Q2. The gain of this cell is set by the ratio of R9/R5 with C4 providing a slight high frequency boost. The collector of Q1 offers a convenient pick-off point for video destined for the sync strip circuit (described later). Meanwhile, the collector of Q2 drives the next amplifier stage. Transistors Q10, Q11, and Q12 form a discrete (inverting) operational amplifier. The output of this amplifier appears at the emitter of Q12. The JFET switch, Q20, is used to sample the DC level at the back porch of the video signal at Q12 emitter. This DC is monitored by U20 and an error signal is fed back into the emitter of Q10, effectively clamping the back porch to ground. U30 serves as a high speed switch (keyer) for the insertion of decoded captions/text. Its two inputs are pins 2 and 3. Pin 2 is the actual video signal while pin 3 is simply a DC level set by R40 to facilitate insertion of alphanumeric characters at the output cell (discussed later). A key signal from the closed caption controller arrives via R44 and switches U30 between its two inputs. The output of the video keyer appears at the emitter of Q31 and is applied to the output cell via R51. In the chrominance channel, the keyer (U4) and output amplifier (Q13, Q6, and Q113) are integrated with output level adjustment provided by R202 and insert balance adjustment provided by R95. The other path taken by the video signal from the input cell provides both sync and caption information to the closed caption controller. This signal is initially amplified and its polarity is corrected by Q100 and Q101. A chroma trap, L100 and C102, removes the chrominance from the incoming video before the signal is sent on to the sync stripper (Q110, Q111, and Q112) and the closed caption controller (U80). An additional low pass filter, Q102, R109, and C103, is inserted before the closed caption controller to reduce any noise present on the video. The output of the sync stripper appears at the collector of Q112 as a negative-going 6
IEC-788 TECHNICAL DESCRIPTION (CON T) TTL composite sync signal. This sync information is used by the sample pulse generator, Q21, to drive the switch FET, Q20 (described above) and by U90, the horizontal pulse generator. The two stages of U90 serve to first remove the vertical component of the composite sync signal, then to regenerate a horizontal sync pulse of the proper width as required by the closed caption controller. The closed caption controller, U80, accepts the low-pass filtered video from Q102 and the horizontal pulse from U90 and produces five output signals: 11. Character luminance, the alphanumeric information that is added to the keyed video via R65 and D52. 12. A key signal from pin 17 (referred to as the box on the schematic). This signal controls the keyers U30 (luminance) and U4 (chrominance). 13. Red, Green and Blue character outputs. The operating firmware places the device in monochrome mode and only the Red output is used. Operating mode of the closed caption controller is determined by the setting of the five toggle switches SW80 (Captions/Text), SW82 (Channel 1/Channel 2), SW81 (Field 1/Field 2), SW121 (Off/XDS/On), and SW122 (NTSC/PAL). These switches are monitored by the micro-controller, U1 and a two-wire serial data interface (I 2 C) controls U80. Power-on reset is accomplished by U3 (which resets U80) and by U2 (which resets U1). The luminance output cell consists of Q50, Q51, Q52, Q53 and associated circuitry. Its configuration is non-inverting with output impedance of 75S. The power supply is a simple linear design. Transformer TX120 features dual primary windings which are switched by SW124 to allow operation at 115/230VAC. Metal oxide varistors (MOVs) V120 and V121 provide over-voltage protection. The secondary is wired in a full-wave bridge configuration with U120, U121, and U122 providing -12VDC, +12VDC, and +5VDC regulated outputs, respectively. 7
PRODUCT WARRANTY Link Electronics, Inc. Link Electronics Inc. warrants its product to be free from defective material and workmanship for a period of TEN-YEARS from date of shipment, including parts and labor. This warranty excludes the HDE-3000 High Definition Closed Caption Encoder & PCR-8200 Video Disc Recorder, note1. Labor performed at the Link Electronics factory in Cape Girardeau, Missouri. This warranty does not extend to products which have been subjected to misuse, neglect, accident, incorrect wiring, alteration, improper installation, or used in violation of instructions from Link Electronics. Link Electronics makes no other warranties, express or implied, of merchantability, fitness for a particular purpose, or otherwise. Link Electronics liability for any cause, including breach of contract, breach of warranty, or negligence, with respect to products sold by it, is limited to repair or replacement by Link Electronics, at its sole discretion. The product must be shipped to Link Electronics, freight costs prepaid. Repaired or replaced equipment shall be shipped customer surface freight only, to be paid by Link Electronics. This warranty is in lieu of all other warranties, expressed or implied, with respect to the condition or performance of any Link Electronics products, its merchantability, or fitness for a particular purpose. The product warranty will be null and void, if a specific component part should become obsolete by the manufacturer. If the component part becomes obsolete and not available through distribution, Link Electronics, Inc will not be responsible for repair or replacement of a Link Electronics manufactured product. In no event shall Link Electronics be liable for any incidental or consequential damages, including loss of profits. SERVICE INFORMATION In the event that the Link Electronics equipment should fail, you should contact the Customer Service Department and request a Return Authorization (RA) number. At that time, the details of how the repair should be processed will be discussed. All inquiries relating to either parts replacement or warranty service should be directed to: LINK ELECTRONICS, INC., 2137 Rust Avenue, Cape Girardeau, Missouri 63703. Attention: Service Department. Phone: (573)334-4433. Fax: (573)334-9255. This WARRANTY supersedes all previous warranties, whether implied, written or verbal, Date, October 1, 2005. Note 1: See the Warranty for the HDE-3000 & PCR-8200 for the warranty period of this product. 8
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IEC-788 FRONT PANEL IEC-788 REAR PANEL PRT-700 RACK TRAY 10