Samsung LE52B620 - Flickering backlight

[sliceypete]

Hello All,

My Samsung LE52B620 started to have backlight flickering about a year ago, it would only last for about 10 mins and then the backlight would stay on.

about a month ago the backlight flickering is constant and does not stop.

I think it's a problem with the power supply board (BN44-00267b) or maybe the backlight is dying?

I checked and all the caps look to be fine.

I do not believe it is a problem with the mainboard, since I unplugged it from the power supply and the backlight came out but still flickers.

I've attached a picture of the power supply board.

Here is a video of the flickering occurring (uploaded to YouTube)

Note: the longer the TV is on the brighter the screen will become, when I first it on, the backlight is quite low.

Thanks again for the help guys!

[lotas]

Re: Samsung LE52B620 - Flickering backlight

There may be ring cracks here, try soldering

[sliceypete]

Re: Samsung LE52B620 - Flickering backlight

There may be ring cracks here, try soldering

Hello Lotas,

Thanks for the suggestion.

Ok I reflowed the solder in these areas.

If I turn the TV with the mainboard unplugged, the blacklight turns on for about 5 seconds and then turns off.

With the Mainboard plug, I get no backlight when turning out the TV. (I can see the menu's if I put a flashlight to the screen)

[Davi.p]

Re: Samsung LE52B620 - Flickering backlight

Common problems through the models are when lamps are connected through connectors , the burnt or oxidized part, bad connection on inverter to balance board cables, bad caps are not possible since the inverter has an AC output.

[lotas]

Re: Samsung LE52B620 - Flickering backlight

There is also an open or interturn short circuit in the windings of inverter transformers, check the resistance of the windings, it should be the same.

[sliceypete]

Re: Samsung LE52B620 - Flickering backlight

Hello Lotas,

I bought a cheap multimeter and checked the resistance of those spots and the readings were the same. (23.8 & 0.4, see attachment)

What would be the next thing to check? also thanks for all the help so far!

[Davi.p]

Re: Samsung LE52B620 - Flickering backlight

already said, unless you don't read me..

[dick_barton]

Re: Samsung LE52B620 - Flickering backlight

Is it the backlights flickering or the image flickering. Hard to tell from your video. Does the set have a Test Picture in the set up that you could show.

[sliceypete]

Re: Samsung LE52B620 - Flickering backlight

Is it the backlights flickering or the image flickering. Hard to tell from your video. Does the set have a Test Picture in the set up that you could show.

it's the backlight that is flickering not the image, I order a replace power supply board off ebay.

Will update with results when it comes in.

[cheeky2]

Re: Samsung LE52B620 - Flickering backlight

Personally speaking if the power supply resolves your issue then I would swop over the two high voltage caps highlighted from your good one to your faulty one just to see if they are faulty and breaking down.

[sliceypete]

Re: Samsung LE52B620 - Flickering backlight

Personally speaking if the power supply resolves your issue then I would swop over the two high voltage caps highlighted from your good one to your faulty one just to see if they are faulty and breaking down.

Great suggestion! I will try this out if the new power supply board fixes the problem.

[sliceypete]

Re: Samsung LE52B620 - Flickering backlight

Personally speaking if the power supply resolves your issue then I would swop over the two high voltage caps highlighted from your good one to your faulty one just to see if they are faulty and breaking down.

The replacement board arrived last week and the TV worked after I did the swap.

I ordered some 22pF 6KV high voltage ceramic capacitor from ebay to replace the ones from my old board.

After replacing the two high voltage caps you pointed out, the old board it works without any flicker!! My TV is back up and running!

I think I will keep the replacement board just incase I run into anymore problems in the future. (if anyone on these forums needs a board, just PM me)

I really apprentice all the help I received!

[cheeky2]

Re: Samsung LE52B620 - Flickering backlight

I had a similar issue with on a LG power board which was the high voltage capacitors which were breaking down so that's why I suggested solution.
Glad you resolved the issue