Repairing a Samsung buffer board - possible ? (image persistance, VGL pin fault)
Good day folks. I decided to "revisit" this Samsung UE40F5000 TV I've talked about in a previous thread which inexplicably died during an LED replacement. Originally, it came in with no backlight in the top portion and after replacing the dead LEDs, we put it back together and to everybody's dismay, there was no more picture AT ALL. I eventually had no choice but to conclude it's a bad panel, without having a clue as to HOW it actually died by just laying flat on the table, but anyway.......we had no choice but to buy the guy a new TV, but I was also left with the dead one, so after some time, I decided to dust it off and try and figure out what's really wrong with it, since I've learned some tricks in the meantime 
So this brings me to my actual topic: is it actually possible to repair a buffer board ? I concluded the left (or right, really when you look at the screen from the front) buffer board is somehow busted. Here's what happens: when the buffer is not connected to the T-con board, all the voltages on the T-con board are correct: 1.2v, VGH (35v) and VGL (-6v). However, when I plug in the buffer in question, everything on the T-con dies - 0v on all these test points. I tried probing around the buffer board, hoping to find a short, but I couldn't find any, at least not on any of the discrete, visible components. I then tried a trick I learned from some "kids" on a local repair website: placing a piece of tape over the VGH and VGL pins respectively and see which one causes the voltages to drop. It turns out it's the VGL pin that does this, because when it's not making contact with the t-con board, but the VGH one is, all the voltages stay up and there's even picture coming on screen (true, it looks very bad on the affected side, but it IS there). If I remove the tape and allow VGL to contact the T-con, the previous problem reoccurs. The image persists because there's not VGL to "discharge" the panel. The guy who came up with the idea was lucky enough to have a faulty VGH pin, so the right side of his screen didn't come on at all. I couldn't exactly trace where the VGL pin is going, but I assume it goes to that component at the end of the buffer board in the picture. Is it this thing ? Does this project have the slightest chance of success, or is it dead from the get-go ? Cheers.
So this brings me to my actual topic: is it actually possible to repair a buffer board ? I concluded the left (or right, really when you look at the screen from the front) buffer board is somehow busted. Here's what happens: when the buffer is not connected to the T-con board, all the voltages on the T-con board are correct: 1.2v, VGH (35v) and VGL (-6v). However, when I plug in the buffer in question, everything on the T-con dies - 0v on all these test points. I tried probing around the buffer board, hoping to find a short, but I couldn't find any, at least not on any of the discrete, visible components. I then tried a trick I learned from some "kids" on a local repair website: placing a piece of tape over the VGH and VGL pins respectively and see which one causes the voltages to drop. It turns out it's the VGL pin that does this, because when it's not making contact with the t-con board, but the VGH one is, all the voltages stay up and there's even picture coming on screen (true, it looks very bad on the affected side, but it IS there). If I remove the tape and allow VGL to contact the T-con, the previous problem reoccurs. The image persists because there's not VGL to "discharge" the panel. The guy who came up with the idea was lucky enough to have a faulty VGH pin, so the right side of his screen didn't come on at all. I couldn't exactly trace where the VGL pin is going, but I assume it goes to that component at the end of the buffer board in the picture. Is it this thing ? Does this project have the slightest chance of success, or is it dead from the get-go ? Cheers.
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