Ok, what on earth is wrong with this 7000?

Vectorman

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Guys,

Another one that has me stumped (again). Look at these pictures. Monitor works, recapped, new FB (tried 2 different new FB), but for some reason the picture is way brighter (or over driven) on the left side of the monitor, and dim on the right side. It is not the tube - does it on every 7000 tube. It is also not on the neck board - tried swapping with known good. Anyone else solved this one? Oh, and it SEEMS like it's related to the green mostly. I know, I should have tried changing the green input transistors.... is that it?

Thanks for any guidance you can offer!!!

John "vectorman"
 

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Those are purity issues. Either the yoke has come loose or got dislodged/moved or the rings on the neck have. If the yoke came loose you can kinda adjust it and push it back up against tube while its on but do not touch the copper windings, you kinda need to know where is safe to touch. If its the rings this can be more complicated, the rings can also slide forward or backward on the neck and or the front two closest to the tube adjustments also deal with purity. The back 2 sets are convergence.

This is 100 percent a purity issue because of how the green is bleeding into the red. It also helps to turn the contrast down and the color pots when adjusting the purity so the bleeding dosent give you false reads.
 
Wait you said it does this on multiple tubes?! I find that hard to believe, this looks like classic purity issues. Or maybe a degauss problem. So say your pots were over driven then the whole screen would have a green or blue or red tint not just part of it. The only thing i can think of is the chip on the neckboard causing a weird color issue on the 7400 series chassis but im not so sure its capable of causing random colors across the screen only the tubes purity can but i coukd be wrong unless someone installed a giant magnet on the chassis lol. A b+ set waaay to high can also cause weird problems.
 
Wait you said it does this on multiple tubes?! I find that hard to believe, this looks like classic purity issues. Or maybe a degauss problem. So say your pots were over driven then the whole screen would have a green or blue or red tint not just part of it. The only thing i can think of is the chip on the neckboard causing a weird color issue on the 7400 series chassis but im not so sure its capable of causing random colors across the screen only the tubes purity can but i coukd be wrong unless someone installed a giant magnet on the chassis lol. A b+ set waaay to high can also cause weird problems.
K7000s don't have LM1203s lol they're ancient technology by comparison. the IC1 is what handles the color processing duties though.

@Vectorman I would start over with the brightness and color white balance adjustments and see if that makes a difference. my monitor fu is weak at this moment and this is something I've never seen before. you may need to enlist @arcadecup in the interest of science.
 
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