K7000 working but screen pulsates, shows random white dots

Vectorman

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K7000 working but screen pulsates, shows random white dots

Guys,

Got another 7000 question. I've got a 25" 7000 that I've capped and it works with a decent picture. But the picture pulsates. Like the focus waves slightly in and out, making the picture look like it's bulging, then focused, then bulging, etc.

Also, while this is happening, there are random little white dots (or short lines) that show up around the screen, like static or something. 2 or three per second. As the monitor is on longer, more of the dots show up. Then the picture starts also to shake and act like it's going to go out, but it doesn't.

Unfortunately, it's one of the junk Zenith chassis.

Anyone know what's causing this? (BTW, I know it's the monitor. Tried a different iso trans, and a different monitor and the problem is only on this monitor).

Thanks,
John
 
pulse

Check cap by regulator and replace regulator. If this did this before cap kit then replace regulator. Did you replace the 47uf 160v cap?
the dots more then likely are comming from your isolation transformer. Take ground off chassis frame. if it does not have a ground to the frame then attach one and see if that helps. ground problems are weird but this usually cures that problem.
 
I got the random dots to go away. The problem was the next board had kind of been smashed into the tube (my employee must have done it...I didn't know) and so one of the pins on the neck was bent and not making connection. After bending that pin back and reattaching the neck board, the dots are history.

But now I need to try to deal with the pulsating problem. I'll try the filter cap and the VR.

Stay tuned...

John
 
well, tried replacing the VR and the filter cap...still pulsating slightly. I'm inclined to just not worry about it. You only notice it during attract when the picture freezes on something. But during game play you can't tell it's so minor.

Any other suggestions?

Thanks,
John
 
It could be flyback related, but there are no replacements for that model.

Other than going around and checking it for cold solder, or maybe connecting another monitor to make sure it's not power related, it's probably not worth shotgunning parts into...
 
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