Posted By
MMS
on 2021-07-22
04:45:12
 |  Re: Commodore 16: Black and white screen on Composite, color on the RF
I tried to find similar cases from the past on other forums, but I could not.
Most of the cases incompatible signals, or bad video cables used, but not in this case.
I agree with one of Hifi's previous comments.
As the TED, the xtals, the video cable closed out, and the RF tuner picture has color. The later proves, that on the board the color signal exists from TED, but fail to reach the video cable via the A/V socket, and that one receives the color signal from tuner via the CN7.
As the modulator generate the composite signal and passing the color signal to A/V too, the failure should be in the modulator or the coils between the modulator and the CN6 connector. I do not say the crystal, as then the RF output also should not have a proper color.
The only logical answer is that there is a defective component / broken track / cold soldering between the video socket and the tuner. As the Composite and the separated Chroma signal also have the failure, I may close out the EM3-EM5 coils too. I highly suspect some bad component or cold soldering within the modulator.
(a small crack could be at the bottom of the connector too. It you press it with the multimeter measuring pins, it may cure it temporarily).
Please try to touch or even move every little component in the tuner to close out bad connection betwen the component and the board.
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