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Screen uniformly dim. Briefly got back to normal then happened again

My 60uj6050 lg tv’s screen got very dark one day. Tried all recommended settings,even factory reset the tv. Didn’t help. But then, a few hours later we turned it on, and it was fine. A few days later, the problem came back, this time for good.

Here’s the information:

  • no amount of fiddling with settings helped
  • Screen is dark, not black. No need for flashlight
  • picture is uniformly dim. No stripes, no halves, or spots
  • Bought a power supply board and motherboard from shopjimmy. The parts that I got didn’t look like new parts. Neither fixed the problem.

Before buying backllight strips as the next logical step, I have doubts. Based on what I understand, uniformly dark but not black screen is more likely to be caused by power supply. Could it be that shopjimmy sold me parts pulled from broken units, and the one I got was broken? Or does it sound like a clear case of burnt backlight? What do you make of the fact that picture briefly returned to normal before going bad again?

The last question might point to the diagnosis.

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I have the same issue. It started months ago and performing a picture test would bring the brightness back to normal- did this four or five times over a period of 6 months or more and it seemed to be when the TV was first turned on. Today this would not fix it. I reset the AV and adjusting brightness from 50-100 had no effect on the picture. The picture is still there but very dim, like 10-15% of normal.

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@James Dietzel what model is your TV and what voltages do you have going to the backlight LED's from the power board?

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Hi @minifixit ,

Uniformly dim is different to not being on at all so it may be a resistive connection (loose/corrosion?) somewhere.

Check the connections/cable from the power board to the backlight LEDs first and then it may be at the LED strip connections.

One way to find out maybe without dis-assembling the panel, is to purchase a TV LED backlight tester - examples only and check the brightness of the LEDs by disconnecting the LED power cable from the power board and connecting the tester to the LED power cable.

As the LEDs will be powered by the tester and not by the power board this will help to point to where the problem lies, i.e. the LEDs or the power board (or possibly the mainboard if the power board is receiving an incorrect voltage level signal from the mainboard to dim the LEDs check the cable between the mainboard and the power board)

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It might be helpful to know the power supply output voltage for the LEDs if this works that way.

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I've had several LG tvs that have had this problem and lost the 1st one because of not catching it in time but the problem is often due to my power cord. The cord provided with the tv must be cheap because After losing the 1st one all I had to do to the other ones is pick up a new cord at my local walmart and use it instead of the one provided. If you catch it early enough within a week of the problem initially occurring the problem will fix itself with a new cord. Plug the tv in with the new cord, if its bright enough to see the menu turn off energy saving and set picture to vivid and if it does fix itself it will do so within 1 to 2 hours depending if the charge diodes gets back to a proper charge. If it doesn't then the diodes have been damaged due to lack of power and the entire power supply board will need replaced. I could fix my older tv if I had that power supply board but it was a limited 3D TV so the power supply board isn't common enough to be found cheap.

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What is a "Charge diode". Never heard of it.

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So have u fixed the problem

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Update 1: it could be a problem with electrical arcing in the wall power socket causing probable dirty power supply...used another wall outlet and the situation became better.

Update 2: another cause is that the tv storage had become full due to redundant cache files from apps and the settings are not saving full reset seems to fix it .

i am having this problem with my 2.5 yr old phillips tv too recently .. the picture quality became slightly dull and blurry as compared to before, not a lot but noticeable to trained eyes.its as if the gamma is dark even though the gama is set neutral value 0.

I have switched the to a different wall socket and changed the power cord to another same one ( from soundbar which is used as well ) and the situation is better.. wil try changing the power cord to a brand new and see how it goes. If i am right there is something wrong with these pwoer cords as they seem to be giving problems after a while of use.

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The only thing that might cause that is a resistance developing in the cord. That would reduce the voltage to the TV. That would be easy to check with an ohmmeter. It should be pretty close to 0 Ω on each side. You can also feel the cord when the TV is on. A resistance will generate heat. I would suspect at the connectors.

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@ruggb an update to the post

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