How do I know the power board is bad not the sustain or main board?
I reflowed the transistors and transformers on the main power board, no bulging or leaking caps.
Power on, grey screen for fraction of a second, then powers off. Red light goes away on power on, then comes back when screen dies, fades away then solid.
Thanks for the question. My name is XXXXX XXXXX X'm sorry to hear about your TV.Have you measured Vs and Va voltages?Best,Dan
No, can I do that with a basic multimeter? and I am assuming they are labeled on the outputs of the board.
Miles,Yes, they're labeled. TV needs to be on, so put your leads in place first... then turn the TV on. Nominal values should be on a sticker inside the TV. Va is usually 65VDC... Vs is usually 185VDC or so.Dan
OK, 60 VDC for Va checks Good187 VDC for Vs, probably still rising but TV shuts off. (195-204 VDC spec written on main power board)
Miles,Ok good work. There is no reason to suspect a defective power supply. Have you looked closely at all three scan boards on the left, and also the sustain board on the right? You're looking with a magnifying glass and a bright light, for any pinhole-size burns, melt marks, smoke marks, etc.Anything?
All clean, no scorches or burns, melting, smoke.
Miles,Standing behind the TV, the scan drive is the large board on the left with heat sinks on it. Disconnect it from the power supply. Now turn the TV on. You won't have a picture, but does the TV power on and stay on?Dan
No it does the same thing (power on, then clicks off) but now no whine from the scan board.
Ok. It's not the power supply, the scan drive, or either of the scan boards. It's either the main board, sustain, or the plasma panel itself.Go ahead and reconnect the scan drive board to the power supply, then disconnect the sustain board (large board on the right with heat sinks on it), then power on the TV. Some sets don't let us run this test but it's worth a shot.Does the TV power on?
Same, on then off, no change in time. Main board is $20, couldn't hurt to try a new one.
Miles,It's either the main board or the panel. The panel is very rare to fail, unless there was some physical contact. Yes, I would replace the main board.Dan
USAF trained; currently teaching electronics for the DoD.
replaced mainboard, everything is the same, I checked the PDP boards, but they seem to be power and signal distribution only, the amps are in the ribbon cables.
Miles, Then you have a bad plasma panel, unfortunately. Sorry to bear such bad news, but the panel would be far too expensive to consider replacing. It would be wise to replace the TV, in my opinion.Dan