Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

[Tuned]

First I had the "click of death" - TV did not turn on. Then I replaced faulty capacitors and cleaned up soldering joints (power supply). Power supply was fine for a while - and then when hot the picture would go after 15 minutes or so - but the sound would stay on. Where do I start looking? Power supply or Y-sustain or Y-buffer or what? Or do I just get a big hammer and beat the thing to death?

[dick_barton]

Re: Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

You could check what voltages are failing when losing the picture after 15 mins.
Use freezer spray to cool down components to try and isolate the component causing the problem.

[vinceroger69]

Re: Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

also check the soldering on the psu on any components mounted on the heatsinks as they have a habit of cracking around the solder joints even if look good maybe worth re flowing them with fresh solder.

[dick_barton]

Re: Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

+1
Plasma do seem to have problems with dry or cracked solder joints so I would meticulously check all the boards for any defective joints. The effort could prove worth while.

[Tuned]

Re: Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

Thanks dick barton and vinceroger69. It does seem like it could be failing voltage to the Y-sustain board - and I have already re-soldered one of the components (transistor) on a heat sink. It was so loose that it was sparking. I will check the voltage and also the soldering. Would a Y-sustain board be OK when cold - but when hot not work?

[dick_barton]

Re: Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

Yes, this can often be the case. Again due to poor solder joints, a failing component or component going out of spec when hot.

[vinceroger69]

Re: Samsung PS-50C91HD - after 15 minutes picture goes off but sound stays on.

parts some time heat up when hot and shrink when cool hence working for a time period so when cool makes good contact and works, when gets hot/warm solder joint expands and breaks contact thats my theory.