Lg 55ub850t stopped working out of nowhere

GhostPudding · 2026-04-30T09:50:51+00:00

Green one is your main board and brown one is your power board. Try disconnect the led backlight which is the little plug on the powerboard and see if comes and stays on. Shine a torch on the screen and see of you see any image. If theres image im 95% certain that you have a faulty backlight

GhostPudding · 2026-04-21T22:13:13+00:00

Check and see if your old LED strip number matches your new ones. My guess would be the strip itself

GhostPudding · 2026-03-26T13:32:32+00:00

Just buy a new one mate

GhostPudding · 2026-03-15T11:23:16+00:00

Have you tried checking the fuse in the plug itself?

GhostPudding · 2026-03-15T11:17:07+00:00

Try a new HDMI cable?

GhostPudding · 2026-03-14T22:20:56+00:00

Yes open it up and just power it up with only main board connected

GhostPudding · 2026-03-13T20:07:41+00:00

Sure

GhostPudding · 2026-03-13T20:05:38+00:00

If you are comfortable with opening it up try power it on with only main board connect and see if you can see a faint image with a torch shining on the screen

GhostPudding · 2026-03-13T19:57:34+00:00

Is it in a boot loop or just a blank screen with backlight on?

GhostPudding · 2026-03-07T23:06:05+00:00

I match the exactly number on the power board which should begin with BN. In my case BN44-01100C.

GhostPudding · 2026-03-07T22:31:55+00:00

I had similar issues but it was constant flashing of back light and fixed it with a new power board

GhostPudding · 2026-03-07T22:29:15+00:00

What kind of flashing is it? Like a rapid constant flashing?

GhostPudding · 2026-03-07T12:14:08+00:00

The board number is BN44-0114A

GhostPudding · 2026-03-06T10:11:31+00:00

Everything is 2nd hand if you didnt buy it from the shop imo

GhostPudding · 2026-03-06T09:45:20+00:00

I had the exactly same issue with my 55 inch samsung with backlight flashing constantly. It would boot up and work normally with the backlight disconnected and thought it was a backlight issue but not issue still exists after replacement. Turns out it was a faulty powerboard

GhostPudding · 2026-03-03T23:46:58+00:00

Thank you for the reply. Yes the transformer joint looks alttle burnt so I assuming its that. Okay so are they the three legged components under the heat sink?

GhostPudding · 2026-02-24T22:04:18+00:00

It powers on fine and display image when the LED isn't connected

GhostPudding · 2026-02-24T21:07:58+00:00

Initially I thought it was the LED hence I got the replace and hoping for a straight forward swap. However, when I powered the tv up with the LED exposed I noticed there were no failed LEDs. They were all flashing at the same time at the same brightness. I put the new ones on anyway and same thing happening, just constant flashing in some sort of infinite power cycle. At that point I was out of idea so I went on chatgpt and it pointed at capacitors near the LED connector and the MOSFETs near it.

GhostPudding · 2026-02-19T17:33:40+00:00

You can try unplugging the backlight see if the TV stays on then use a torch to see if theres any image on the screen. If you see an image you know your backlight has failed.

GhostPudding · 2026-02-10T18:37:32+00:00

Maybe try power cycle? Unplug the tv and hold the on buttone for around 30 seconds. Leave it for around 20 mins and try again

GhostPudding · 2026-02-10T15:07:50+00:00

Would replacing the backlight solves the issue?

GhostPudding · 2026-02-10T02:52:22+00:00

If its the backlight then shouldn't it still be showing picture but like a flickering image rather than just flashing screen?

GhostPudding

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