LG 55GA6450-UD LED backlight fails but returns after power cycling

[gustagen]

I am 4 for 4 with TV and monitor repairs with this forum's help.

I recently acquired an LG 55GA6450-UD LED TV with a backlight issue.

It powers up and works normally for 1-5 minutes, then the backlight turns off. Audio continues to work and the picture can be seen with a flashlight.

If power is cycled, the backlight functions again for 1-5 minutes, then turns off. I tested this over 20 times.

The screen looks evenly lit when displaying an all white image.

Thanks for any help you can offer!

[budm]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

Try turning down backlights (not brightness) level to as low as possible on all inputs and see if it will stay on longer.

[gustagen]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

I turned the backlight level down to 0 and the TV has been working for 20 minutes now.

[budm]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

LED failure is common problem in TV with LED backlights.
You can read many threads at this site about them.

[gustagen]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

I was afraid you'd suggest that the LED strips were the problem.

I successfully replaced all of the strips in a 32" LG back in August with your help, and then set the backlight level to 65%. It's still working fine.

This 55" LG has panel LC550EUN and driver PCB 6917L-0118A. It appears that its LED strips are much more expensive and harder to source.

[budm]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

It looks like your panel use edge lit LED.
Full panel model number is LC550EUN-SFF1?
https://www.ebay.com/itm/695mm-LED-B...-/122572974585
Can you still see good pictures at 30 ~ 40 % backlights setting and will it stay on? If you can live with lower backlights then I would use it until it fails completely.

[gustagen]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

Thanks for the additional info.

I didn't realize the panel was edge lit, and was assuming I'd need several of the single LED strips I was seeing for sale.

How many strips are in the TV? If it needs only one or two, the expense seems more reasonable.

It seems this panel is LC550EUN SF F2. I've attached a photo of the label.

Do edge lit panels require the same type of disassembly as the back lit models, or are the strips replaceable without removing/handling the LCD panel?

In the meantime, I'll experiment with slightly higher backlight levels.

[budm]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

I could not find anything much about the LED strips for the SF F2 (LC550EUN-SFF2) panel.

[gustagen]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

I've had some time to test the TV at higher backlight levels.

It seems to work fine with the backlight set to 35%, and I'm satisfied with the picture.

Thanks again budm!

[budm]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

That is about the same level I used on my LG, it is more then bright enough for my eyes, if they would have limit the drive current through the LED's then they would not have been getting bad reputation about LED failure.

[jbb4670]

Re: LG 55GA6450-UD LED backlight fails but returns after power cycling

I have the same model tv and just recently the top left corner has gone darker than the rest of the image. I noticed what happened was when I was watching tv that area got really bright then it went dim and has been that way since. it is not completely out but you can see the difference. since this is an edge lit LED is it fair to assume that I would need to replace just the strip? one tech guy was telling me that the entire panel would need replacing and it would cost over $900 which I found to be quite absurd. has anyone taken apart this model and replaced the strips?

any help and suggestions would be greatly appreciated. thanks!