Re: LN40B540P8F Flickering Backlight

Thanks for sharing those pics. I didn't see anything like that with my lamps. Perhaps they're just not far gone yet. I may just wait and see how long this lasts with the back light turned down a bit. The transformer came in a two-pack...

I've gotten the impression that the Samsung protection circuit used here it just extra touchy. I've noticed that with some models, people are disabling it altogether by clipping a jumper. Thankfully, I haven't gotten that desperate yet.

Re: LN40B540P8F Flickering Backlight

Well replacing that transformer seems to have done the trick for now. I'm not sure what made it go bad in the first place, but all the CCFLs seem to work fine. I left the back light turned down just a bit, maybe it'll last longer this time.

The trickiest part was getting the CCFLs plugged back in after removing the power supply incorrectly. Luckily I was able to create a method for getting them plugged back in to their sockets without disassembling the panel any further. I just looped short pieces of waxed string around each lamp's...

Re: LN40B540P8F Flickering Backlight

I'm curious to know how these transformers are hooked up. With there being multiples, do they each power a portion of the backlight? If so, why does the bad one disable the entire backlight? Unless it were shorting and causing an over-current condition that tripped the protection circuit. Even then, why would it stop shorting when the backlight is turned down to 2? Turning down the backlight setting just changes the modulation percentage, not the voltage...right?

It's obviously a damaged transformer, I'm just curious about why...

Re: LN40B540P8F Flickering Backlight

It's a BN44-0264B. I pulled it out to inspect the solder joints, and found nothing obvious. Unfortunately, I'm not sure what the best way to reinstall the board is. The ends of the CCFLs are quite floppy, and don't want to engage with their connectors. Is there a quick and easy way to access them from the other side, or must I dismantle the entire TV now?...

Re: LN40B540P8F Flickering Backlight



BN44 sounds right, I'll check the other digits and get pics when I get home. I think it ended with a 'B'......

Hello, our Samsung TV has started flickering. I've got the back off, and can see the backlight flickering on and off through the small holes in the sheetmetal. Here are some things I've noticed so far:

-I can hear a light buzz when the lights are on, and it's silent when it goes out. Possibly just normal inverter noise?
-I have 386VDC on the main filter caps
-I don't see any bulging caps
-I don't see any overtly burned components
-T1803 has some very light discoloration on the tape around its core
-Energy saver mode is already off
-If I turn the...

Re: LG 50PC3D-UD Power Supply Repair

Thanks for posting the results of your repair. So many people never follow up, and the thread dies as soon as they find a solution!

I just picked the same TV for free, and it exhibits the exact same problems. I'm curious if it was just the MOSFET that kept your TV from turning on though? I suppose a short on the ZSUS would probably send it into protect mode. Maybe I'll pull my power supply out and bench test it with light bulbs like you did.

Either way, hopefully I'll meet with the same success!