I must guess you got the service manual so let's say you can't diagnose which it is from that. Here's some sage advice I got years ago. Ready? Replace the cheapest suspect part first.
Bob
I have a Samsung PN50C590G4F plasma tv from Feb. 2010 that wont turn on and the relay on the power board clicks on and off repeatedly with the front led flashing. When the set is trying to turn on the VA reads 55, the VS 211 and the VSC -198. The VE reads 92 when the relay clicks off and then drops to 81 when the relay turns on. I replaced the X board thinking that was a problem but the same numbers are on the meter reading with the new board. When I bypass the number 3+4 post of the logic board the screen comes on with the test colors but again turns off after about 6 seconds. I don't see or feel any popped capacitors and all ribbon feeding voltages to the y board, logic board and main board are correct as written near their terminals. Please offer testing suggestions and or solutions.
Thanks
Brian

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