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Old 05-18-2018, 11:50 AM   #1
guix
New Member
 
Join Date: May 2018
City & State: Troyes
My Country: France
I'm a: Knowledge Seeker
Posts: 19
Question Short circuit on Y Buffer board, or bad panel ?

Hello,

Someone gave me a plasma TV Samsung PS50C530, which didn't turn on. It's the first plasma TV that I open and try to repair. I have repaired some LED TV but it was mostly simple things like replacing backlight or capacitors.

I found shorted components, and an exploded disk capacitor, on the Y Main board, so I bought an Y Main board on ebay, but when I installed it in the TV and tried to turn it on, it blew up instantly. All I saw was a few random white pixels on the display, then I heard "pak" from an unknown place (can't see any damaged component on any board) and now the "new" Y Main board shows the same problem as the old one, with shorts on multiple components. I also checked Va and Vs (with Y Main board disconnected so the SMPS could start) and those two voltages are good. I know the TV sound is working because I connected a HDMI cable, turned the TV on (still without Y Main) and could blindly select the HDMI input withthe remote, and heard the sound from it. Also the LED on the Logic Board flash at 1Hz.

So I think the problem might be, either a bad panel, or a bad Y Buffer board. I did the Y buffer test as shown in youtube videos:

But couldn't find any shorts (I tried with all other pins on the white connectors too).


However I think I've found that all "big" diodes and resistors are shorted:

My multimeter beep when I touch the two side of diodes like the one in this picture. This is bad and shouldn't happen, right !?? I tried to remove the diodes but the shorts are still here after removal. When I measure resistance across these resistors I always get around 2 ohms. As you may see I've removed the hot glue from a chip but not sure what to test here because I don't find the datasheet for that chip (Panasonic AN16489A).

Do you think that this Y Buffer board is bad and caused both Y Main boards failures ? And may it have originated from a bad panel ? I don't see any damage on the panel itself, however the TV bezel is damaged like if it felt on concrete or gravel:


I'm wondering about buying a new Y Buffer, and again a new Y Main (and also X Main maybe, however I can't find any shorts on that board, but does that mean that it's good?). But before I do so, is there anyway to check if the panel itself is good and won't blow up the new components instantly?

Here is a picture of the whole Y buffer board:



What do you think about it? Thanks!
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