[miniman82]

So, you're saying the color smears from red to something else from top to bottom depending on the setting of horizontal hold?

Are you running the signal through the antenna or composite input? I suppose it's possible for the tuner or IF to be slightly out of whack one direction and the color circuits to be skewed in the opposite direction causing it to get confused (some sort of odd phase shift or somesuch), but it should be noticeable in normal viewing if it were that far off.

Try this: whenever I troubleshoot a color problem, I always inject a signal at the first video tube's grid (NTSC signal). That eliminates the tuner/IF as a possible source of confusion. If it's still doing the same thing, you know the issue lies in the chroma/demodulation section and you should focus your efforts there. My guess will be that the CW osc transformer (Sams A36 and A37 respectively) is tilted too far one way, and because the feedback signal for the AFC is taken from one side of that transformer, it's easy to see how even with correct colors on the screen a slight imbalance will throw the whole thing off. In other words, I've found that it's possible to have that particular transformer set with correct colors on screen, but have an overall phase shift with respect to burst that it tends to get the AFC circuit all bent out of shape.

It's the color equivalent of the horizontal circuit being on the verge of falling out of sync, so you're seeing the color 'pulling' just as the whole screen would tend to tear when on the edge of the horizontal sync pulse.

I think this is because the color burst is gated by the horizontal flyback pulse, and if those 2 transformers are set incorrectly it will try like hell to lock in but it's too far off for an automatic lock. What happens to a set of color bars when you ground point 'M' in the Sams? If you get a rolling color rainbow, your AFC is out of line with respect to burst. If that's fine, my money is on A36/37 being tuned incorrectly.

Best way I've found to get those 2 close to good is have color bars on screen, and tweak them both till you zero in on a normal looking pattern. You can look at the grid signal from the CRT with a scope to try and get the ladder to look right, but I always just tune it by eye.

Hope this helps, but I really didn't think it would be possible to have vertical color tearing. Sounds like a strange problem indeed.