Service manual

CB-11
IF Receiver
The remaining outputs of the IF processor are the AFC control to IC6000 from pin 14 and the IF video
signal which passes through the AV-switch (IC2900) as it travels to the comb filter. AFC output voltage
causes the microprocessor to determine any frequency corrections the tuner needs to make for a better
signal. A portion of the luma from the IF-video is separated and filtered for the purposes of signal detection
at pins 5 and 6 of IC6000. From the main video signal, this separation occurs after the comb filter stage,
where composite video exits IC2900 at pin 34. Signal detect information (SD) is then separated from the
luma by transistors Q1240 and 1241 and their surrounding circuitry. For the second video signal, luma is
taken immediately from the IF video signal out of IC1250 and separated by the circuitry including Q1252
and 1253.
Part Location Part # Notes
IC1200 221-00792 All Models
WT1200 175-02770 All Models
IC1250 221-00792-01 All Models
WT1250 175-02770 All Models
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