Chosen Solution
I took in a vizio E420-B1 (LED NOT SMART) Power Supply has no standby voltage, all 4 12 volt outputs stay active at all times, led voltage is 26,1 volts across the terminal, now if you power tv on and off a few times led voltage will jump to 35 volts and led and tv works fine for about 15 mins then shuts off, when this happens you have to do the power on and off procedure allover again until you get luck and it powers on.
Hi @electricmonkey , Don’t know the answer but it may be quicker and easier to take the shotgun approach and replace all the boards. Here’s a supplier that sells a “board kit” for a Vizio E420-B1. If the TV meets the serial number requirement for the “kit” (see note in link regarding TV serial number) it may be an option to consider.
