Hello, been a while since posting and always appreciate this forum and the help.
Picked up an LG OLED77C2PUA that does not turn on.
The standby light does come on when plugged in. Pressing the on/off button on TV (or LG remote) the red light turns off for 1 second and comes back on steady. I took off the back panel and tested the power supply. When pressing the power button, the 20V and 12V to Mainboard spike to 19.9 and 11.9 for a few seconds then slowly drop back off. Can tell the supply is coming on for 2-3 seconds. The 12V to TCON also spikes to 11.9 then drops back to 0. The two 23V to TCON remain at 0 with pressing power button.
Disconnecting two LVDS TCON --> Panel and nothing changes.
I disconnected the lower cable from TCON --> Mainboard and got results:
TV powers on and provides audible LG power on tune. The panel stays black, however, there is a single half inch multi-color band on right edge of screen (left if looking from behind fyi). Further inspection with flashlight and TV off reveals tiny hairline crack in bottom right corner - 2 maybe 3 mm in size. Also dark spot here when powered on again, with the multicolor band (lower cable to MB disconnected). Can get the band to flicker with light pressure on panel here as well.
Checking PS to MB and now every pin gets expected (3.3, 11.9, 19.9 etc.) and stays that way, Tcon gets 12V, and the two TCON 23V are also good. Think PS is good but happy to post pin results if needed.
Disconnecting the LVDS from TCON --> Panel one at a time: left no change. However with the right out, the left side of panel (right side from behind) comes on with white/grey vertical bands.
Had already ordered a new TCON online from ShopJ before discovering the hairline crack so installed that, and got all the same above results.
Reading this forum, and not fully discouraged by the crack due to its tiny size and proximity to corner, I also disconnected the TCON EVDD (that wasnt getting 23V originally) on PS side just to see. Nothing changes with the TCON--> Mainboard cable in, however, with it out, and the right TCON--PANEL LVDS out, the entire screen lights up white/grey vertical bands across entire screen, with some distinction along the right edge vertically (above hairline crack), and now horizontally bottom (along hair line crack).
In this state - the screen also stays lit even with power on/off cycling.
So - my assumption is bad panel and can part out the boards?
Any chance the MB is also having issues? There does not appear to be a red Optical/Audio light.
Any chance the tape trick on panel LVDS could work (I did some testing without results).
Thanks in advance for any assistance. I know thats a lot and wanted to give a comprehensive description. Will post some photos.
Picked up an LG OLED77C2PUA that does not turn on.
The standby light does come on when plugged in. Pressing the on/off button on TV (or LG remote) the red light turns off for 1 second and comes back on steady. I took off the back panel and tested the power supply. When pressing the power button, the 20V and 12V to Mainboard spike to 19.9 and 11.9 for a few seconds then slowly drop back off. Can tell the supply is coming on for 2-3 seconds. The 12V to TCON also spikes to 11.9 then drops back to 0. The two 23V to TCON remain at 0 with pressing power button.
Disconnecting two LVDS TCON --> Panel and nothing changes.
I disconnected the lower cable from TCON --> Mainboard and got results:
TV powers on and provides audible LG power on tune. The panel stays black, however, there is a single half inch multi-color band on right edge of screen (left if looking from behind fyi). Further inspection with flashlight and TV off reveals tiny hairline crack in bottom right corner - 2 maybe 3 mm in size. Also dark spot here when powered on again, with the multicolor band (lower cable to MB disconnected). Can get the band to flicker with light pressure on panel here as well.
Checking PS to MB and now every pin gets expected (3.3, 11.9, 19.9 etc.) and stays that way, Tcon gets 12V, and the two TCON 23V are also good. Think PS is good but happy to post pin results if needed.
Disconnecting the LVDS from TCON --> Panel one at a time: left no change. However with the right out, the left side of panel (right side from behind) comes on with white/grey vertical bands.
Had already ordered a new TCON online from ShopJ before discovering the hairline crack so installed that, and got all the same above results.
Reading this forum, and not fully discouraged by the crack due to its tiny size and proximity to corner, I also disconnected the TCON EVDD (that wasnt getting 23V originally) on PS side just to see. Nothing changes with the TCON--> Mainboard cable in, however, with it out, and the right TCON--PANEL LVDS out, the entire screen lights up white/grey vertical bands across entire screen, with some distinction along the right edge vertically (above hairline crack), and now horizontally bottom (along hair line crack).
In this state - the screen also stays lit even with power on/off cycling.
So - my assumption is bad panel and can part out the boards?
Any chance the MB is also having issues? There does not appear to be a red Optical/Audio light.
Any chance the tape trick on panel LVDS could work (I did some testing without results).
Thanks in advance for any assistance. I know thats a lot and wanted to give a comprehensive description. Will post some photos.
I have this tv
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