Backlight flickering

[ainarssems]

Hi

Got LG 42LG300 LCD TV with flickering backlight. There are no caps that are visually bad. Checked 24V voltage to inverter and it goes to 26V when first switched on then drops to 19V. If inverter is disconnected it stays at 26V.

What do you reckon should I replace inverter, power supply or change caps on power supply even if they are visually OK?

[Ltank]

Re: Backlight flickering

Can you post pics of the inverter and power supply board?
LG has some sets that the fix is cutting a jumper. Other sets
have capacitors that are in rectangular holes in inverters that looks ok but need replacing

[ainarssems]

Re: Backlight flickering

Pictures attached.

[Ltank]

Re: Backlight flickering

Even though the caps may look ok. Change the three caps on each inverter boards. Use quality caps. Not general purpose or radio shack. I use Panasonic FC or FM caps

[tom66]

Re: Backlight flickering

I'd try replacing C114 the red poly cap
Check PFC bus voltage too (across big 450V cap) you may have to trace it and probe at the drain of a transistor for example.

[ainarssems]

Re: Backlight flickering

I test fitted larger 1000uF 50V caps on inverter as they were closest that I had available at home( original are 680uF 35V) and no change.

My gut tells me it's more likely to be power supply issue and I found one cheap enough on e-bay so thought I will give it a go. Business seller, 15k plus feedback and 99.5% positive and only £17.99

http://www.ebay.co.uk/itm/271562004687

[ainarssems]

Re: Backlight flickering

Changer power supply and all working fine.

Thanks for assistance