Dec 8, 2022, 12:24 PM
Post #1 of 1
LG 43uj6200 42" TV turns on for a fraction of a second, then goes blank
This is a much asked about question:
LG Smart LED TVs that turn on for a second, show the LG logo, then a black screen ensues.
My TV is a LG 43uj6200 TV.
I have tried the typical troubleshooting steps involving holding the power down for 15 seconds while unplugged, then waiting up to 15 min, then holding down the power again while it turns on. No fix there.
I am getting the 3 red blinks, but the system will stay on (at least the motherboard does). 3 red blinks indicates that it is a power supply issue, from what I read.
Also, I visually looked at the mainboard for faulty caps (leaky or busted cans). Nothing visible. I have read that there is a power diode that could be bad. I did a diode check on all diodes near the "blue rectangular component" (possibly a relay?) None of the diodes showed an open circuit or an infinite voltage.
I do not have an ESR/LCR meter but am going to get one in a few days.
I measured the voltage on the output of the power board and it is supposed to be 13.2 volts. I got 13.08V. Measuring the second to last pin (P-ON), I got 3.2V. I am not sure if that is up to par. I think 3.3V is the requirement for the mainboard.
The last pin at the bottom of the connector is called INV-OK or something like that. I measured 2.85V there. Are these voltages within spec?
I have also read that the LEDs could be open circuited or failing which would draw more current than the power board can handle. This could also cause the shutdown.
Does anyone have any other repair tips for this? I really don't want to have to buy a new power or mainboard.