LG 55LB5610 Backlight Pulsing

[azzicles]

Hey guys,

Just wondering if this is a common issue with this TV?

Everything was working fine and then suddenly the backlight started pulsing. It's on for about 50ms and off for around 1 second, in a constant loop.

I stripped it down to the LED strips and found an LED that's almost short and doesn't work, but if they're all in series, one bad LED shouldn't cause any issues should it?

Is it usually the strips, and if so what's the failure mode? Or is it more than likely the PSU?

TV Works fine except for backlight. (LCD/Inputs/Audio/OSD all OK)

Thanks!!

[budm]

Re: LG 55LB5610 Backlight Pulsing

When the current is flowing the LED gets hot so it goes open circuit, then it cools down then the current starts flowing again. Since you know you have at least one bad LED so why not replace it?

[azzicles]

Re: LG 55LB5610 Backlight Pulsing

Thanks, I ordered some strips. I was going to just replace the individual LED but there's no test pads on either side of the LED so you have to remove the lens. Also I'd assume once one LED fails you're better off replacing the entire backlight?

Thanks

[budm]

Re: LG 55LB5610 Backlight Pulsing

Replacing the whole strip is easier than replacing each LED.
You can scrape off the white coating on the strip to get to the bare copper trace to test the LED if there is no test pads.