samsung 50" plasma, no picture, no obvious short or blown fuse.

[tom66]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

What is the panel Vset rating? Low Vset should cause a prominence of dead pixels.

[mph8783]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

It doesn't list one and there are no obvious signs of lost pixels.

[tom66]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

Can you post the picture of the panel sticker? (Has Vs, Va etc on it.)

[mph8783]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

You can see it all in the photos I posted at the start of this thread. I have put the back cover on again now.
I was wondering if it could be VSet + Va = Vs as that works out about right (173V).

I also have a theory that as the caps age, they cause ripple and spikes to find their way to the buffer IC's which blow, then take out the Y-Sus. Therefore if when the panel starts to show higher levels of noise and sparkle on the blacks (which I had for the last couple of months) the caps are changed, it may avoid the more costly and complex FET & buffer failures - just a thought....

[tom66]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

Va has nothing to do with Vset and Vs, it is completely independent of those. Va is used to program the image onto the panel through the bottom X drivers. Vset and -Vsc is used to prepare the panel (priming.) Vs is then used to make the programmed image appear. There, you know how a PDP works .

Your theory has some merit. A lot of the time it appears on these boards a small electrolytic tends to fail. This probably causes the Vg (15V) to drop out. The drop in 15V leads to maldischarge (Vset/Vsc poor waveform) but also increased heating in the FETs. Perhaps this then leads to the FET failure, which proceeds to nuke the buffer board.

[rabmac]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

Hi m8 can u post a picture of components you changed or part numbers hav same tv sound no picture ,seems identical prob just need to no wat parts and on what boards need replaced thanks

[mph8783]

Re: samsung 50" plasma, no picture, no obvious short or blown fuse.

There can be several causes of the fault, if you think it is the same as I had the you should do three things:
1) buy a standard repair kit for your y-sus board. eBay has them, just search for your y-sus board part no.
2) check for shorts on the buffer boards (youtube has info) and buy however many buffer ic's you need. If you haven't replaced fine pitch smd components before you may want to buy a whole board.
Don't power up tv with repaired y-sus with possible faulty buffer board attached, it may blow y-sus again.
3) replace any other capacitors that look swelled up.