Chosen Solution
TV shows the LG logo on power up then is black. With a flashlight I can see display when accessing menu mode. The TV has sound. I have the back off and there are no bulging caps. The leds flash when turning on the tv (probably during the logo display). how do I determine driver board, power board or led problem?
driver board connection
testor
@sdp1234 check the voltages on your power board to the backlight LED’s (set your meter at something like 200-250V and let us know what voltages you get. You can measure the voltages on the power supply against hat is printed on the board. See your pictures #2. My first suspect here would be the backlight array having failed. LG has had bad issues with this on their models. If your voltages are okay you may have to consider replacing the backlight. For that you will have to dismantle your panel . PITA but doable. Just do not mix up or turn any of the diffuser sheets over etc.
Hi @sdp1234 , Here’s a link to a section from the service manual that may be of some help. Near the bottom of the flowchart it says to “Make sure the Inverter control P401 2pin : High”. Just a thought.
Hi @sdp1234 I’ve worked on a few models of LG smart TV that have this exact issue. The fix was to replace the backlight strips, even though they all worked on the backlight tester. My best guess is that the worn out LEDS were pulling more amps to function than the power supply could safely deliver, causing it to auto shut-off after turning on perfectly for a split second. For a quality replacement part I would recommend replacing all strips at the same time with new ones from Shop Jimmy. I’ve used their parts for years with no complaints. Best of luck with this repair!
