Samsung led TV power board

[Beats]

Hi,
Have a Samsung led TV that after six months wouldn't power on, suspected the power board or something on the power board so bought a replacement and fixed the TV.
I still have the old power board and understand alot of the faults with these can be fixed by replacing caps and other components, if that's possible I'd like to learn how to diagnose and fix the power board I have.

I've added some pictures, if anyone has any info on what to test or how to find the fault I'd love to give it a go. I can solder and have rework station etc.

[CapLeaker]

Re: Samsung led TV power board

If it wouldn't power on, so either the 5V STBY is missing ( then the LED up front will not light up either ) and the whole TV is dead as a door nail.
Also could be that the 5V STBY is working, but the rest of the power supply is not. So we would need more information on what that PSU is or is not doing.
So for starters, be careful working on a open power supply, everything on the primary (hot) side is connected to mains. There can be over 400VDC on the main filter cap, so be warned. Other than that, plug the PSU in and see if you get pin 12 A5V Stby voltage to GND pin 10 on the secondary (cold).

[awyatt2]

Re: Samsung led TV power board

I would start by testing the bridge rectifier the two fuses and the surge suppression on board first. could be also a fet, transistor ,diode or cap. on the caps you would need an esr meter.

[Beats]

Re: Samsung led TV power board

Hi,
Standby light was still working it just blinked when trying to turn the TV on, I tested the 2 fuses before I bought the replacement board both were working, not sure which are the bridge rectifier and surge suppressor and how id test them?
Thanks

[CapLeaker]

Re: Samsung led TV power board

take a 1k ohm resistor and jumper A5V to PSon. Plug the PSU in and check the voltage rails (5V and 13V).

[budm]

Re: Samsung led TV power board

Check the DCV between the two legs of the main filter cap after you force on the board with the resistor in place to see if you do have >360V (should be close to 400VDC), if not, you will need to fix the PFC Voltage booster first.