Hi all,
I have been reading these forums for a while trying to fix my TV and it's been a great help, but now I am stuck and am hoping for some advice. I have a Samsung PS51D550C1MXXY plasma, built in 2011. My brother was watching it a couple of months ago and heard three cracks and then it went dead.
When I started to troubleshoot it I found that Vs and Va were coming up to normal levels but then quickly shutdown. From reading online I learned that later Samsung models will shut themselves down if a problem is detected. With the y buffer, y-sus and x-sus disconnected from the power supply, the PS_ON bridged to GND, pins 3 & 4 jumpered on the logic board and the LVDS cable disconnected Vs and Va would come up on the power supply and stay healthy. As such I suspect the power supply is OK.
I then tested V_sync and Ve and found that neither voltage was established correctly. After some testing I found that that V_sync was shorted to ground on the y-sus board. I tested all the transistors and found an IGBT and diode that had shorted out. I couldn't see any damage to the driver chip nor the IGBT adjacent to the failed one but nonetheless I replaced the diode, the two IGBTs and the driver IC. I have attached photos showing this area of the y-sus board and the affected parts. Note that I also checked for a short across the two test pads on the y-buffer and also checked all the transistors on the x-sus and found nothing out of the ordinary.
The diode finally arrived the other day and I just installed it. Unfortunately the TV still does not work. On the plus side the V_sync and Ve voltages are now correctly established before the TV shuts down. I have tried putting it in test mode again but am still unable to get any picture or sound.
I am not sure where to go next. It could be the y-sus board which I repaired but I am also thinking it could be the y-buffer as I understand these can be affected by a y-sus failure. I am leaning towards replacing both the y-sus and y-buffer boards but would be interested in further advice.
I have been reading these forums for a while trying to fix my TV and it's been a great help, but now I am stuck and am hoping for some advice. I have a Samsung PS51D550C1MXXY plasma, built in 2011. My brother was watching it a couple of months ago and heard three cracks and then it went dead.
When I started to troubleshoot it I found that Vs and Va were coming up to normal levels but then quickly shutdown. From reading online I learned that later Samsung models will shut themselves down if a problem is detected. With the y buffer, y-sus and x-sus disconnected from the power supply, the PS_ON bridged to GND, pins 3 & 4 jumpered on the logic board and the LVDS cable disconnected Vs and Va would come up on the power supply and stay healthy. As such I suspect the power supply is OK.
I then tested V_sync and Ve and found that neither voltage was established correctly. After some testing I found that that V_sync was shorted to ground on the y-sus board. I tested all the transistors and found an IGBT and diode that had shorted out. I couldn't see any damage to the driver chip nor the IGBT adjacent to the failed one but nonetheless I replaced the diode, the two IGBTs and the driver IC. I have attached photos showing this area of the y-sus board and the affected parts. Note that I also checked for a short across the two test pads on the y-buffer and also checked all the transistors on the x-sus and found nothing out of the ordinary.
The diode finally arrived the other day and I just installed it. Unfortunately the TV still does not work. On the plus side the V_sync and Ve voltages are now correctly established before the TV shuts down. I have tried putting it in test mode again but am still unable to get any picture or sound.
I am not sure where to go next. It could be the y-sus board which I repaired but I am also thinking it could be the y-buffer as I understand these can be affected by a y-sus failure. I am leaning towards replacing both the y-sus and y-buffer boards but would be interested in further advice.
Attached Files
Comment