General > General Technical Chat
Why do backlight LEDs burn out and go blue?
<< < (5/20) > >>
Siwastaja:
More likely the backlight consists of RGB LEDs and R, G have failed for a reason or another. Or, the signal chain has failed regarding R and G.

Very unlikely this is due to using white LEDs with slowly failed phosphors to the point image is completely blue. But of course, that's possible, too.

The fact that others have seen the same failure to the point it's a very common issue is interesting, because it should indicate someone knows the likely cause. This should make your life easier; Google further until you find an explanation from someone who actually investigated what's wrong. But obviously if you refuse to investigate and fixate into the initial idea of white LED phosphors failing like in one documented case in an LED lightbulb with external phosphors, then there is nothing we can do.

Fixation is a bitch. Airplanes have crashed thanks to fixation. I feel sorry for you, but good luck.
Twoflower:
Could that be that the TV uses kind of 'remote phosphor'? Some TV-Sets use blue LEDs with a bar contain the phosphor or nano-crystals (most of them contain cadmium!) to transform the blue light to the specific spectra required. If that piece fell off/moved that only the light from the LEDs enters the diffusor of the LCD?

But often there are LEDs on two edges (if not spread over the background). That would rule out the idea the the remote phosphor bar is the culprit unless both fell of the same way. Unless the TV experienced any kind of stress (quick change or high temperature, vibartion...) that made fell off the phosphor?

EDIT: I missed the point that you actually mentioned that it was on at full whack. So the LEDs ran hot and the phosphor might have been damaged/detached from the LEDs.

I think RGB LEDs for background illumination is not commonly used anymore. From what I've heard too many problems with the uniformity of the used LEDs (brightness, aging, color...) and too expensive.
bdunham7:
Here's a photo of failed LED strip from such a TV.


themadhippy:

--- Quote ---They don't.  Your TV is in blue mode
--- End quote ---
is that for viewing adult movies?
ealex:
@bdunham7: that's exactly how the leds looked like in the LG i've recently repaired.

the phosphorus layer was flaking off, and most of the leds where pure blue.
there where no signs of overheating.

the fix was easy, but handling the huge glass pane is scary

@eti - i don't think you can desolder those, they are bare dies on the pcb, with a lens glued above.
the replacement led strips are cheap, just take care to get the proper ones, and maybe some good / thin double sided tape
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod