Chosen Solution
Red standby light is blinking. There do not appear to be any bulging electrolytic capacitors, though there is a fine white powder on various resistors, diodes, capacitors and jumper cables on the board.
I note that the blinking seems to be from a reset of some sort as I tested voltages on the power board. A5V remains at a steady 5.3V but the other test points I could find drop to 0 volts every second or two and then back up to their proper voltage (timing coincides with standby light blink rate), B5V 0V to 5.3V, B13V 0V to 13V (should be 12.8V). Thinking I need to replace the power board as the first step, but could it be some other component doing this? When I disconnect the two cables from the power supply board (one goes to another board, maybe the main board, and the other cable goes into a hole towards the screen), the voltages at the test points remain where they should be A5V 5V, B5V 5V, B13V 13V. Is my father-in-law’s TV, he reports this happened during a rain storm. Initially HDMI2 wasn’t working, so he switched the cable to HDMI1 and it worked, but shortly there after it went to the state its currently in (matter of minutes or hours, not sure) Power board removed from TV and plugged to wall emits a high frequency sound, might be normal though? Power Board
Main Board
TCon Board
norlin add a couple more images. Post one of your complete power board and one of the main board. Unplug the cable going from the ower board to the main board then turn your TV on. Let us know if the backlight comes on. If so your issue is probably your main board. The white powder looks suspicion of some blown component but it could really be anything. From the symptoms you are describing it sounds like a bad main board.
