Flashing LED backlight on a LG 60LB650V

[imp]

Hi respected members of this forum,

I've just received a LG 60LB650V LCD (PSU board EAX65423801) that has a flashing backlight. It flashes about every second with one dim flash and the second with full brightness. When the menu is showing on the screen is seems intact without any dark areas. I´ve searched for info about this and most (out of few) cases it was due to bad LED strips which needed replacement. However, my sympthom isn´t quite the same with that dim/bright/dim/bright cycling.

Also worth mensioning is that the voltage on the connector out to the LED strips is changing accordingly with disconnected LED´s. That´s strange? All the capacitors measures fine.

Where should I begin?

Thanks!

[CapLeaker]

Re: Flashing LED backlight on a LG 60LB650V

It's the backlights. Here is what happens: As a start, the LED backlights are not voltage controlled, they are current controlled. So the PSU is looking for a certain current draw from the backlights. LED's can fail in a weird way, the can work fine for a few seconds, then not. Don't get distracted too much and fix what you know isn't right.

[imp]

Re: Flashing LED backlight on a LG 60LB650V

Thank you CapLeaker for the info and advice, I will dismantle the TV soon and find the correct parts to replace the LED's with. It's well worth the effort and money, it's a great TV

[imp]

Re: Flashing LED backlight on a LG 60LB650V

Found the problem

Just ordered a complete set of new LED strips from Aliexpress and hopefully the TV will become as new again.

Thanks again for a great forum with all the kind knowledgeable members!

[tvtimmy]

Re: Flashing LED backlight on a LG 60LB650V

I would get some white electrical tape to cover up the burn on the plastic led cover sheet.

[imp]

Re: Flashing LED backlight on a LG 60LB650V

I would get some white electrical tape to cover up the burn on the plastic led cover sheet.

Yup, either that or some white paint. I guess it must be reflective in some way too?

[CapLeaker]

Re: Flashing LED backlight on a LG 60LB650V

scrub the crap out of it with 99% IPA