Chosen Solution
Hi all, I am currently at a stand still with an issue. My LG TV (70LB656V) will work power on and function fine, however, as soon as a movie, video or TV starts to play, the LED backlights will power off after a random amount of time. Troubleshooting: I have managed to extend the time by turning power saving onto maximum and turning the brightness down to 50%. Power supply board (EAY63072301) has a red LED light on, which appears to flash a fault code of 4. Voltages to LEDs seem normal until failure occurs. There is 120v from the heatsinks on the MOSFETs to ground (Is this normal?). Question: I would like a second opinion before i go ahead and purchase one, but does the issue occuring sound like Power fault, or LED fault? And does anyone happen to know the meaning of the fault code on the power supply board? Thanks. Update (09/18/2019) @oldturkey03 The LCD still worked fine. I believe I located the issue. A bit more prodding around and I found that there is a LED that is not working, which if I understand correctly, it actually causes the entire array to slowly malfunction over time. Will replace the LED and respond with the outcome. Update (09/28/2019) Turned out there was a blown LED, I have replaced the LED that had blown and it is working 100% again.
@kiwitronics once the backlight has failed shine a flashlight beam at an angle against the screen. see if you can make out the screen that way. If so you know that it is your backlight that has failed. Then you need to give us the voltages for the backlight LED while the backlight is working and what it is when they are not. If the dimming of the backlight helped to make it last longer it is a greater chance that it might be the power supply.
@oldturkey03 as per the photos I checked all 3.5v,12v and 24v terminals while backlights were out, all voltages were as per the service manual voltage screenshot.
My tv is LG 55LB671V. After some time ago my tv started turning off in a random time…. I opened the back cover of my tv and the LD701 LED was blinking 3 times every some seconds… I thought that maybe was the power board, but i also red that if the LED on the power board blinks for 3 times that means that i have an open LED strip. Also when the problem starts i have slound qnd i have not video but when i go closely to the tv on the up left corner i can see the video on my screen with my screen brightness to be very weak. Furthermore, when the problem occurs, i close and i open the tv and the screen is perfect with no problems after the next time. Some times my tv before shut down the screen it creates darck areas on my tv (you can see the screen behind but it is darker than other areas) and eventually my video wi turn off (with the sound to be okay) until i reopen it. So is it is bad strip problem and i have to replace it? Or is it a but connection on yhe strip and i can fix it without any parts.
Can I chip in here with a related question? Very similar fault on an LG 55LB700V Screen goes black after a few seconds, Took the back off and found that the PSU (EAX65424001) is flashing error code 4. Does anyone know the PSU error codes? If I unplug either of the two LED plugs, I get code 3, which I think someone said was OC on the LED string. Makes sense. Before the screen blanks out, I see that it’s evenly lit, so SUSPECT that the LEDs are fine and it’s jsut the PSU, but wanted to be sure before I push the button on a refurb board from eBay.
f I unplug either of the two LED plugs, I get code 3, which I think someone said was OC on the LED string. Makes sense. Before the screen blanks out, I see that it’s evenly lit, so SUSPECT that the LEDs are fine and it’s jsut the PSU, but wanted to be sure before I push the button on a refurb board from eBay."
i have the same symptoms (although the 12v dc rail is down to 11.70v is to low? was wondering if you replaced the PS board? did it fix it?
I replaced my psu board ($80) from Ebay, tv worked perfectly for 2 weeks, but now it`s back to the same… turns on for a few seconds then blacks out….hhhhmmm
