Samsung UN40ES6100 backlight periodic flashing

[TheDandy]

This set's got a backlight that comes on, dims, and switches off periodically. Picture's fine, but the backlight cycles between on and off. All my research seems to point to the BN44-00502A power board, and a buzzing can be heard near the top of the board when the backlight goes off.

Visually inspecting the board, all the caps seem fine and there's no leakage, though there is a lot of residue from the factory on the back. Near the top of the board under some diodes there is some discoloration, but it appears to be present on every example of this board I can find including pristine ones. Inspecting the other boards yields nothing, but just in case I made sure the cables were plugged in properly.

I'm looking to fix the board, if it CAN be fixed, but I'm a total newb at this and am looking to learn as much as I can. I've read some of the troubleshooting guides, and I've got my volt meter at the ready, but yeah- If y'all have any help, advice, or arcane incantations to help get this set fixed it'd be greatly appreciated.

[BIAFRAN]

Re: Samsung UN40ES6100 backlight periodic flashing

You need to troubleshoot the unit causing the backlight intermittent behavior by forcing the power supply board voltages out connecting 1k ohm resistor between standby and ps on to observe if the backlight voltage is steady or fluctuating this must be done without main or logic board connected.If confirmed ok then u need to test the backlight for defective LED.This forum don't respond to assistance arcane incantations.��

[budm]

Re: Samsung UN40ES6100 backlight periodic flashing

This set's got a backlight that comes on, dims, and switches off periodically. Picture's fine, but the backlight cycles between on and off. All my research seems to point to the BN44-00502A power board, and a buzzing can be heard near the top of the board when the backlight goes off.

Visually inspecting the board, all the caps seem fine and there's no leakage, though there is a lot of residue from the factory on the back. Near the top of the board under some diodes there is some discoloration, but it appears to be present on every example of this board I can find including pristine ones. Inspecting the other boards yields nothing, but just in case I made sure the cables were plugged in properly.

I'm looking to fix the board, if it CAN be fixed, but I'm a total newb at this and am looking to learn as much as I can. I've read some of the troubleshooting guides, and I've got my volt meter at the ready, but yeah- If y'all have any help, advice, or arcane incantations to help get this set fixed it'd be greatly appreciated.

1) Do you still hear the buzz if the LED connector is not in place?

2) Can I see the location of the discoloration? https://www.shopjimmy.com/samsung-bn...ply-led-board/

3) Can I see the LED connector in place so I can see how many wires are on the connector?

[TheDandy]

Re: Samsung UN40ES6100 backlight periodic flashing

1) Do you still hear the buzz if the LED connector is not in place?

2) Can I see the location of the discoloration? https://www.shopjimmy.com/samsung-bn...ply-led-board/

3) Can I see the LED connector in place so I can see how many wires are on the connector?

1) When the LED connector is disconnected the buzz i'm referring to cannot be heard. You can still hear a faint electrical hum if you put your ear right up to the board, but the sound I'm referring to is quite a bit louder, though it still can't be heard unless you're up close.

2 & 3) Attached are some closeups of the board in situ, as it were, cables and all. Near the top of the board underneath some diodes, visible in the first image, is some brown chocolatey discoloration, to the right of the heatsink and to the left of the capacitor.

[budm]

Re: Samsung UN40ES6100 backlight periodic flashing

That is LED power supply section, It may have some shorted LED.
Do you have LED tester?
BTW, those diodes and caps in the brown section tested OK, correct?