Video distortion on TV tube

Jun 01, 2011 4 Replies

Okay, I've fixed the vertical hold problem mentioned in another string of posts, and now the bottom of the picture is overlaid or superimposed over the top of the picture, at the top of the screen,. I was thinking this is most likely an adjustment, but couldn't find the pot that affected it and ended up pulling the CRT out to gain access to and adjust a variable inductor at the back middle of the PC board. So now the problem is not as bad, but it's still there. I'm guessing this is some sort of wrap-around, but have no idea as to what to do about it. Any suggestions? Surely this isn't the first time something like this as happened with a TV. There are four pots on this board, but one of them doesn't seem to do anything to the picture, so I am trying to leave it where it was. If anyone has any ideas, I'm all ears.



Thanks bunches.



Dave


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How about a make model, year age info, etc?????

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Sounds like your original problem was height or linearity, not vertical hold.

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Replace the bad electrolytics in the vertical output particularly if it's inside the feedback look. Sony 8" color monitors are notorious for this. Don't screw with the pots but I'm sure you already did. If you ever need to move things more than 10% it's broken or somebody did what you're doing now. Diddling but it won't take long to correct once the bad caps are gone. And don't buy cheap crap. Look for highest ripple current.

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It's foldover. Common problem. Replace the boost capacitor, and maybe the B+ cap for the vertical output.

Mark Z.

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