K7000 color issue- Looks Psychedelic

Gump79

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I just did a cap kit and replaced the flyback on a dead 25" K7000. I got it back in the machine and I noticed when I tapped on it the screen you get a flash red. I pulled the chassis back out and found the yoke and input connector pins had some broken solder joints. I reflowed all the solder pads and now the screen is totally red. I also did a rejuvinate and balance on it to make sure it wasn't a tube issue. I followed the flow chart and it looks like either IC1 or transistor on the neck board is bad?? I'm going to try and swap some parts. I also have an issue where there are green blotches in two of the corners. The monitor is out of a T2 and normally live horizontal I had it stading up whine waiting for parts and to work on so I'm assuming that it needs to be degaussed? When I plug it in R105 is instantly hot to the touch (burning) so I don't think the ADG is working if I'm reading the manual right? Does anyone know the replacement for R105, the manual just reads thermistor but no specs? Am I way off on this or am I heading down the right path?
 

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Probably just need to degauss it. If you have degaussed it and there are still blotches like that, then you'll have to go through and set up the purity.

The thermistor is supposed to get warm. That's how it works. It's in series with the degaussing coil. It heats up and then goes high resistance, shutting off the degaussing coil. It is NOT supposed to smoke or burn though, and it shouldn't get ridiculously hot.

-Ian
 
Also, on the red screen problem - the transistor on the neckboard could be shorted, or you could have a heater-cathode short in the tube. Since you have a tube tester, and you can easily check the gun for shorts, you probably already did that, so it's probably the neckboard transistor. All three drive transistors are the same, so try swapping the red one for one of the others and see what happens. Or, remove the red transistor entirely - then you should get no red. If you still get a solid red screen, it's the tube.

-Ian
 
you can also check Q1 on the chassis by the video input header. if that transistor is bad it will give you a full screen of color or no color at all.

the other two above it are for the blue and green so you can swap them as well to see if the problem moves.

but it is most likely the neck board transistor. check it and check your work to make sure you did not solder the legs together,

after that and you get it fixed manually degauss it before and after it gets put back in the game.

yes the thermistor is supposed to get hot but not cherry red.

Peace
Buffett
 
I replaced Q1 and swapped Q201 and Q202. Still the same issue. I also rechecked the tube on the B&K just to make sure, tests good. IC1?? The degaussing circuit must have kicked on because the Green in the corners is now gone so at least one issue is resolved....
 
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