Chosen Solution
I have a Samsung model#un55eh6001f powering on and off constantly, power supply looks good no expanded caps, I already changed motherboard ran for 3 hours then same powering on and off. Thanks John
twolittlebigfeet start of by disconnecting the motherboard rom the power board. Let us know if your backlight turns on and if the TV stays on. Let us also know how it turns on and off and if it does so by itself. Does the whole TV turn off or does just the screen goes black. Next you need to measure the output voltage from the power board to the main board. the values for the connector voltages are printed on the board so let us know what those voltages are. Also, post some good pictures of your boards with your question. that way we can see what you see. For now this sounds like a power board issue but we definitely need more information. Adding images to an existing question
