Ctc12 Chroma circuit schematic

[andy]

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[reeferman]

Sure, I'll PDF it at work tomorrow.

When you pull the color osc tube, does it rainbow? As I recall, it should (turn color up 100%).

If I recall correctly, ground pin 2 (grid) of 3.58 osc and adjust L702 (reactance coil) for slow drift/stationary rainbow. Definitely check area for cold solder joints. Also, the crystal can be bad. If you have a known good one, I'd slap that in after checking all the surrounding PCB.

If you get the color back, adjust reactance coil, and the adjust 3.58 osc coil, for good flesh, with tint control mid range, watching a quality broadcast.

Good luck,

Phil

[andy]

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[Chad Hauris]

It seemed like there was a problem in the detector circuit that produces the correction voltage along with the crystal problem in a CTC-15 clone I worked on.
The detector I think is a 6JU8 quadruple diode (chroma sync phase detector and color killer detector): have heard of tube failures here.

[andy]

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[reeferman]

Glad to see you have the sync back. From the first photo I could tell the sync was off because the rainbow was horiz and not vert. The further off the freq is the more lines you'll have. Ground the grid on the reactance tube. As you adjust, you may go through the horiz then vert. scenario several times. Your best adjustment will give the least number of, but widest (floating) vertical bars

Next thing you need to do is to get a halfway decent convergence on the set. You'll be amazed with your progress.

[andy]

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[reeferman]

Check V707a and associated components for the green problem.

Once that is fixed, try this to center your tint. Ground pin 2 of V703B 3.58 Osc tube. Adjust L702 reactancecontrol coil for minimum # of vertical color lines/bars. Tune in a show of known good color quality. Adjust the tint to midrange, adjust T703 3.58 Osc Trans for correct tint.