I've got a Chinese OEM 50" PDP with Samsung panel and components. The TV brand is Vivo (purchased from the former Australian electronics retailer Dick Smith Electronics)
It failed to turn on a month back and I found a shorted power FET on the DC15V power supply line, ordered and replaced it. I highlighted the FET in the photo.
Now the PSU starts (PS_ON signal goes active low and stays low), the switched secondary voltages come up, look like they hit protection and then the voltages slowly drop as the secondary filter caps discharge. The PDP momentarily flashes a white raster showing it's still alive.
All standby voltages are up and stay stable. If I disconnect the cable delivering VS and VA to the rest of the set, the power supply still behaves the same, by going into protection after VS and VA fire up.
I can't find a schematic for this board. I'm having trouble finding why it's going into protection since there are six optocouplers providing feedback between the hot and cold sides and what appears to be a general purpose microcontroller (MCV14A) on the secondary doing the voltage and current feedback, PSU control and protection functions, so I don't know what to trace and look for.
The markings on the PSU are
43DH PSPF271501B LJ44-00191C (This I assume is for the 43" version)
51DH PSPF331501B LJ44-00192C
51DH SDI
D-Series_SDI
The PDP is
Samsung 850HW-YB07
The TV set model (on the rear panel) is
Vivo PTV51HD
Can anyone please assist in providing a schematic for the PSU or further ideas for diagnostics?
Thank you!
Images: (warning 6mb each)
Front: http://imgur.com/nzOWHhT
Back: http://imgur.com/niIEsUr
It failed to turn on a month back and I found a shorted power FET on the DC15V power supply line, ordered and replaced it. I highlighted the FET in the photo.
Now the PSU starts (PS_ON signal goes active low and stays low), the switched secondary voltages come up, look like they hit protection and then the voltages slowly drop as the secondary filter caps discharge. The PDP momentarily flashes a white raster showing it's still alive.
All standby voltages are up and stay stable. If I disconnect the cable delivering VS and VA to the rest of the set, the power supply still behaves the same, by going into protection after VS and VA fire up.
I can't find a schematic for this board. I'm having trouble finding why it's going into protection since there are six optocouplers providing feedback between the hot and cold sides and what appears to be a general purpose microcontroller (MCV14A) on the secondary doing the voltage and current feedback, PSU control and protection functions, so I don't know what to trace and look for.
The markings on the PSU are
43DH PSPF271501B LJ44-00191C (This I assume is for the 43" version)
51DH PSPF331501B LJ44-00192C
51DH SDI
D-Series_SDI
The PDP is
Samsung 850HW-YB07
The TV set model (on the rear panel) is
Vivo PTV51HD
Can anyone please assist in providing a schematic for the PSU or further ideas for diagnostics?
Thank you!
Images: (warning 6mb each)
Front: http://imgur.com/nzOWHhT
Back: http://imgur.com/niIEsUr