Chosen Solution
This Element E4SW7019RKU TV had a backlight issue in March of 2022. When replacing the backlights notice three or four LEDs had burn marks around them making black marks on the back whitepaper. After replacing the backlights & testing them, there was a clicking sound from the PSU and an over voltage reading to the backlights, and the new backlights did not function. I decided to replace the PSU. Installed the new PSU and TV works. Fast forward to December of the same year. TV started exhibiting the same symptoms as before. No backlights, there are the appropriate images on the screen when a flashlight is used, the PSU is again producing overvoltage to the backlights. When both backlights and mainboard is plugged in voltages are 413 volts 362 volts from left and right output sockets on PSU. Compared to 275V & 82 respectivly when both mainboard and backlights are unplugged from the PSU. Is it possible that the MOBO is at fault here?
Wayne Griffiths the overvoltage can be caused by the failed backlight strips. At this point I would replace the strips again and check the voltage after that. If it is still a concern then, consider modifying the power board to limit the voltage supplied to the strips.
