Samsung / Sanyo DP50747 - no standby voltage

[ahickman]

Weather here is looking grim, so I filled up the stove and pulled up a chair to a 50" plasma set that I had promised a friend I would take a stab at repairs on. Plugged it in and got no response. Immediately removed the back panel and visually inspected boards looking for obvious (fuses, caps and blown components). Found a bad fuse, replaced it and put the set on the isolated transformer. Brought it up to voltage and the fuse blew. Started running through the related components and found Q110 ( 11N80C3) to be bad on the power supply (Samsung PSPF561A01A rev. DR3 0.8). Replaced it and powered it back up. Still no standby voltage on the pin labeled 5stb. Pictures are posted below of top/bottom of power supply. Looking for either a schematic or helpful advice on what to check next. I have read through most of the threads and did not find what I needed. Any help would be greatly appreciated.

[ahickman]

Re: Samsung / Sanyo DP50747 - no standby voltage

Anyone?

[tom66]

Re: Samsung / Sanyo DP50747 - no standby voltage

Which FET did you replace? Can you highlight it?

[ahickman]

Re: Samsung / Sanyo DP50747 - no standby voltage

Q110 has been circled in blue on the backside.

[tom66]

Re: Samsung / Sanyo DP50747 - no standby voltage

I would always replace that little surface mount driver IC in the case of FET replacement. Next to that FET. They can often get damaged by such failures.

[ahickman]

Re: Samsung / Sanyo DP50747 - no standby voltage

Thanks. I assume this is a PFC or other feedback IC?

[tom66]

Re: Samsung / Sanyo DP50747 - no standby voltage

Probably the standby controller - you can look up the part # to confirm - offline flyback switcher or similar.

[ahickman]

Re: Samsung / Sanyo DP50747 - no standby voltage

200D1 PAKC are inscribed on the IC. When I search Digikey, I get two types of IC's (AC-DC controller and DC-DC controller). PN's = NCP1200D100R2GOSCT-ND and NCV887200D1R2GOSCT-ND. Any idea as to which one might be correct?