Panasonic TC-P58vt25 plasma, buzzing and dark screen

[GoneGault]

This was a dumpster rescue in nice condition, but I have no knowledge of it's history. When I plugged it up I could hear relays snap; when I turned it on, I saw a bright point of light in the middle of the screen, then the screen quickly went dark. It then started the typical 7 blink pattern. I pulled the buffer boards and tested them, finding one buffer board shorted. I jumped the pins on SC50, and got a solid red light but the screen was dark. Green LEDs lit up and stayed steady on the SS and SC boards, but a loud buzzing came from the area of the D board....(It is sort of hard to pin down the location--could be the power board). The main power supply board 812MDM has a large 230V 1000u capacitor that may have be swollen on the top; also the sub power board 812MDS also has a large 230v 1000u capacitor that may be swollen on top.
I would be interested in any suggestions on how to proceed.

[tw2005]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

The caps maybe be sus but some of those larger ones can have a slight dome from new. Sounds like you need to relace the buffer and it should be ok but have a good look over the panel for any cracks.

Which board Sd or Su was shorted?

If the the panel gets hit or crackes whilst on, often the Sd will be shorted

[Moreno83]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

As TW2005 says , loud buzzing sound is probably bad panel. You could tighten all screws and check the voltages , maybe someone played with the potmeters.

[GoneGault]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

Thanks guys. It is the SU board that is shorted. If the screen was damaged (maybe when they dropped it off) would it be likely to show a bright point of light when it was started the first time, then nothing else?

[Moreno83]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

Maybe the last bit of gas ignited....., it can be that the gass inside was already gone. The panel then just makes a loud buzzing noise.

[tom66]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

Just carefully check the whole panel for cracks with a flashlight. If there aren't any it should be ok.

[Moreno83]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

Unless someone used to long screws for a board and touched the panel , happened to me once! Still sick about that 1....

[GoneGault]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

Thanks all! I will check the panel.

[GoneGault]

Re: Panasonic TC-P58vt25 plasma, buzzing and dark screen

Thanks guys....you were exactly right. When I checked the front of the panel with a flashlight I found a small holed.