Chosen Solution
Hi, How long do you have to wait before the standby light comes back on and that you can turn on the TV after it has shutdown? Also the “pop” sound might just be the audio turning off as the power is removed suddenly rather than being turned off in a controlled manner when the TV is turned of normally. If you can, try “muting” the audio and then check if the “pop” is still heard if and when it turns off. It may be that something is overheating and shutting down the power and it doesn’t start again until it has cooled down Given that there is no standby light after it has shutdown (I couldn’t see it on in the video after the TV shutdown) it means that the mainboard either hadn’t received the voltage signal from the power board so that the light can be turned on or if it has received the voltage signal, it didn’t turn it on. I can’t find the schematic for the power board but you would have to check if the standby voltage is there after the TV turns off suddenly. A way to do this perhaps is to check for voltage on all the wires in the cable going from the power board to the mainboard when the standby light is on in the TV i.e. the TV has power connected but is not turned on and write them down. When the TV fails and there is no standby light check again to see if any are missing or if they are all there etc. This may be a pointer as to where the problem is, power board or mainboard. Be safety aware if you decide to try this as there is lethal exposed voltage in the back of a TV. If you don’t know how to safely test for voltage when lethal voltages are nearby then don’t do it. Leave it for the experts. It’s not worth it. With a lot of TVs the mainboard turns the power board on when you turn on the TV. The standby voltage coming from the power board is there to tell the mainboard that it is ready to turn on as voltage is there. Also I had a bit of a problem looking at the video and image that you posted, they just kept “hanging” with nothing showing until it eventually came after a lot of trying. Try posting images etc direct on ifixit. Here’s how to do this. Adding images to an existing question
