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Sony KP53XBR15 convergence problem

Hi. Sony KP53XBR15. Red convergence - horizontal size adjustment - from center to right works perfectly. From center to two thirds out to left works perfectly. Far left one third is the problem. As size is adjusted down from as big as it can get, just before it would be correct, far left part of red image suddenly increases in size, running off left side of screen, while rest of left side image continues decreasing in size.

Have replaced STK devices, even exchanging them to see if problem follows chip. No.

Have replaced all low ohm feed resistors and checked all others. No go.

Not heat related. Does it hot or cold.

Have removed and checked all elec caps on board. No go.

Have checked power regs. No go.

Mind you, the blue works perfectly, as does the green.

I can't see it being the size pot.

I scope the red H conv output, and waveform does look different than the blue, but on STK input I can't see any difference. Yokes read okay ohmswise. I don't have a spare yoke or conv board to try in it.

Any constructive thoughts?

Thanks much, Danny

Reply to
<djnoble35209
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Fixed your model #...should be KPR.

I'd suspect the pot if your getting a drastic jump like that. Is there a dead spot in it maybe?

-- ========================== Jeff Stielau Shoreline Electronics Repair

344 East Main Street Clinton,CT 06413 860-399-1861 860-664-3535 (fax) snipped-for-privacy@snet.net ========================
Reply to
Shoreline Electronics

Well, if it affected both left and right, maybe so, but it is dead smooth movement on right side and inner part of left side. Just the far left side is affected.

Danny

Reply to
<djnoble35209

Do you think someone may have tweaked this set before you? These can be a real headache if so. Too many pots!

-- ========================== Jeff Stielau Shoreline Electronics Repair

344 East Main Street Clinton,CT 06413 860-399-1861 860-664-3535 (fax) snipped-for-privacy@snet.net ========================
Reply to
Shoreline Electronics

No. I've known the set since it was new. Belongs to a friends inlaws. I fixed the p/s a couple of years ago. This problem showed up like instantly one day. No one else has ever worked on it, or fiddled with the convergence board.

I also did swap around the little 8 pin op amps, there are like 7 of them, but that had no effect. Was worth a shot.

Danny

Reply to
<djnoble35209

Maybe one of the diodes? That's about all that's left.

Reply to
Ancient_Hacker

Haven't found any bad, like open or shorted yet. There are 2 chips kinda near center of board. One of them may be the problem. Just hate to throw money at it until I have a firmer handle on the problem. The owner is in south Florida for a month so I have some time. I don't have a print of this board, may try and locate one if I have to.

Reply to
<djnoble35209

Swapped CXA1268P chip, I believe IC912. Not in front of it right now, and a

16 pin chip whose number I don't recall right off, both borrowed from a Mits conv board. Only 1 large size IC left on board. Am beginning to wonder about the yoke.

Danny

Reply to
<djnoble35209

Okay. Bad red yoke. Looking for good used one. New is prohibitively expensive.

Thanks for the advice, Danny

Reply to
<djnoble35209

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