K7000 25" Vertical Colapsing

SterlingRush

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This is more of information sharing, as I was able to fix the problem(s), just wanted to give another reference in case others run into this issue.

K7000 25" std res chassis was brought to me, having the black jail bar issues on the screen. We performed a rebuild on the chassis, jail bars went away, but new issue arose. So the issue I will picture below, is what was fixed, by what I will list further below. I'm not sure of the exact fix for this, but this will at least give guidance, of a few spots to check and redo on the chassis.

OK, rebuild consisted of:
-Cap kit
-Flyback
-STR30130
-D1398
-D19, D20, D23, D24
-C38
-New remote board
-Desolder and solder of header pins, pots, ect....


Results gave me this:

CIMG4159_zpsbspg6iay.jpg



CIMG4160_zps7iqdvc2f.jpg



CIMG4162_zpsvo4urnbj.jpg



No amount of adjusting or tweaking, would produce any better results. That was as big as the image would go, with that constant distortion. Looked up Fromm's flow chart, and went through the process. Swapped out IC1, IC2, and C50, tested IC3 pin 6 for +24DC. Same result, had approx +20.3 DC at this point.
 
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Pulled the chassis, went back over all spots myself and the owner had worked on during the rebuild, since the issue seemed to change after our work. Found multiple lifted/damaged traces, and a broken diode leg, that looks like someone had attempted to solder the leg back on. My listing will read as the position with the damaged pad, and what it was jumped to within the same trace:
-R16 to pin 7 of the usually missing P7 board.
-R101 to C23 positive leg
-C40 positive leg to the "B" blue wire(behind the flyback)
-R96 to R89
-C48 positive leg to D25(banded side)
-C48 negative to pin 7 of IC3
-Diode with soldered/broken leg was D21, not replaced with the rebuild
-Tweaked the 50/60Hz pot just a little more


Final result:


CIMG4170_zpsiccozfgs.jpg



CIMG4169_zpseao2yow1.jpg
 
Interesting... will add link to this thread in the sticky...

THANK YOU for the post!! the more info out there, the better.
 
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