Samsung Power Supply Board BN44-00874F

[nomoresonys]

Go ahead and check all the transistors, thats all that start with Q for a short if you haven't already. For those that may be looking on and need to know. Put meter in beep mode, thats the one with the diode on some meters and check each of the three legs for a short, so one probe on leg 1 the other on leg 2 then 3, then go from 2 to 3, if you get a constant beep its shorted. If meter has no beep mode, you can test in ohm mode, if you get close to 0 ohms while doing the same test its shorted.

[nomoresonys]

I guess first order is getting the standby working.

[nomoresonys]

I see, I would probably suspect the IC nearby QP802CS, the one with 14 legs there and maybe check the resistors by your mosfet, and maybe QP804 and the ones near it. See if you can grab a datasheet for that IC.

[Nicktronic]

Yeah, I didn't clean the board up for her photoshoot, but I assure you the solder joints are solid.

[nomoresonys]

Whoa, the soldering of those replaced parts is a mess, that could be the problem.

[Nicktronic]

Hey everyone,

This power supply board is hard to find but there are repair kits available. This board had a blown fuse, FP801S, blown PFC MOSFET, QP802CS and ceramic cap, CP809. I replaced them with parts I already had and tested the rest of the parts that would've come in the repair kit and they were fine. I powered the board up on the bench expecting, in typical Samsung power supply board fashion, to see all my output voltages but, nothing. 0 volts on CNL801, CNM801 and CNT801. The only thing I have is 170vdc on the filter caps. No standby voltage either.

Anybody have a schematic for this board? I'm struggling to troubleshoot without it. Also I'm open to advice on where to focus.

Thanks!