sick sony

[peter g]

hi all, greetings from s. florida. my tale of woe concerns a sony rptv, vintage 1996. model#KPR-4110, chassis #SCC-643A-A. the problem is i cannot converge the red vert lines(sides). this is what i"ve done, so far. 1)changed fluid (all three tubes). 2)checked all caps on convergence bd. for value and esr. checked all caps on main chassis. 3) checked B+ voltages going to convergrnce bd., also 12v reg. 4)checked resistors (convergence bd.).5)changed both output stk's. and several out of tolerance resistors.6)checked both input waveforms int convergence bd.(from E bd.)7)swapped output chips and op amps.(to see if trouble moved). 8)checked pc boards for breaks.in spite of all this checking, i still can't converge the red! i can't believe i could not find one bad electrolytic in this set! this forum is my last resort before trashing this poor sony. thanks. sorry for the long thread. pg

[Eric H]

Moved this to Rect & Solid State, figured you'd have a better chance of getting an answer here.

[AUdubon5425]

Changed the fluid in all three tubes??????

[radiotvnut]

Did you use genuine STK's or the generic $5 (or less) variety. I've had many problems with cheap chinese generic parts either not working at all or going up in smoke after a short period of time.

[peter g]

yes, the company i bought the ic's from assured me they were original sanyo stk's. i paid $30.00 for two.

[kx250rider]

Do all of the controls work on the convergence board? If not, part of the convergence board isn't running. If I recall, and I don't have the schematic in front of me, there are two picofuses on that board that protect the power supply from shorted STK modules. If not familiar with those, they're the size of a 1/2 watt resistor, and are usually black plastic. Those often open when the modules fail. (I could be of on that; the 4110 may have regular glass fuses on the board).

I have to congratulate you for the patience to change that glycerine fluid! That's a son-of-a-gun job, and it's nearly impossible to clean out all the fungus that grows in there. I tried once on a set that belonged to me, to replace the glycerine with water, and it didn't do so well. For customers, I mandated replacing the tube(s) if they had leaked or started to blossom with the fungus. Those were the first generation Sony projection tubes from the early 80s to the late 80s.

Charles

[peter g]

actually this model doesn't have any pico fuses on the convergence bd. all those areas on the board have factory installed jumpers. yes, changing the fluid was pretty labor intensive. pg

[colorfixer]

Could the red tube itself be off kilter?

[peter g]

that could be. although, i used the same procedure(changing fluid) on all three tubes. the question now, how can i confirm that? pg

[julianburke]

Actually the liquid on the tubes is not glycerine. It is clear glycol or antifreeze.
The blue tube is the one that generates the most fungus because of its' light spectrum that supports fungus. (like a grow lamp) Philips/Magnavox was made right here in Knoxville and I saw and worked on plenty of them. I still have some of that ethylglycol in white containers that was meant to be a kit for replacement.

[peter g]

yes, actually, i worked for philips for a number of years. and you would be amazed at what i found floating inside the crt"s. bugs the size of a quarter! always the red and green needed fluid change. pg

[peter g]

sorry, meant blue and green.

[Geoff Bourquin]

I think red light kills whatever that gunk is growing in there.....seems like blue is always worst. Most of those sets are so old now that I wont do that job anymore. I always hated it anyway.

Back to the convergence issue: Maybe an open winding on the convergence yoke?

[peter g]

iam going to check convergence yokes. will post results. pg

[Geoff Bourquin]

Does the red move from side to side at all when you adjust the center convergence? if it moves, but not far enough it could be the centering rings on the red yoke got moved so far that the electronics can't make up for it. A couple years ago I had a set like that, and I could center the color that was off (don't remember if it was red or blue), but doing so caused the IC to run quite warm. (well, scorching hot actually). I put an ammeter in series with the fuse to that IC and set the electrical centering adjustment for that color to draw minimum current then moved the rings to pull the test pattern back in line. I don't know if that ring was out of whack from the factory, if the customer was messing around with things, or if I bumped it while I was working. At any rate, it got it working and the IC ran a lot cooler. The edges were pretty close, and only needed a touch-up to pull them back in line.

I'm just thinking out loud here. Hope it helps