Yes I know a new TV is cheap these days but I don't feel i've had my moneys worth from the current one!
Its a 2007 Samsung 50" plasma.
It has history - 5 years ago a buffer IC & Y-Sus failed - so i fixed it.
Now its gone again, same symptoms of sound, no picture, Y-SUS LED on.
I've removed the offending buffer IC's on the top buffer board so I can confirm the Y-sus is fixed before wasting new buffer IC's and I have replaced the failed FET on the Y-SUS, all 3 caps that come in a service kit, and checked the fuses. Main PSU rails all appear good.
The screen is now priming, the Y-SUS LED has gone off, the Z-SUS buzzes in line with the picture content but still no picture.
Instead it appears to just have some dots randomly lit, more of a sparkle and I note that the Z-SUS bottom heat sink is warm while the top one is cool (its fuses are all OK as well).
I am looking for some pointers to isolate the issue further.
I am assuming that the fault is most likely still with the Y-SUS and the Z-SUS is only half warm as its a black picture.
The logic board has one led flashing steadily and some others on.
Questions I have are:
1) Are all buffer IC's independent - i.e. I have removed the top two but am still expecting the lower two to function normally (I had it running with one off beforehand for a few months as hadn't got round to replacing it! so don't see this as an issue).
2) what voltages (roughly) should a DMM measure on the output of the Y-SUS - everything at present is around minus 120V w.r.t chassis which I wasn't expecting. Unfortunately I don't have a scope available that I trust at these voltages!.
Photo attached
Its a 2007 Samsung 50" plasma.
It has history - 5 years ago a buffer IC & Y-Sus failed - so i fixed it.
Now its gone again, same symptoms of sound, no picture, Y-SUS LED on.
I've removed the offending buffer IC's on the top buffer board so I can confirm the Y-sus is fixed before wasting new buffer IC's and I have replaced the failed FET on the Y-SUS, all 3 caps that come in a service kit, and checked the fuses. Main PSU rails all appear good.
The screen is now priming, the Y-SUS LED has gone off, the Z-SUS buzzes in line with the picture content but still no picture.
Instead it appears to just have some dots randomly lit, more of a sparkle and I note that the Z-SUS bottom heat sink is warm while the top one is cool (its fuses are all OK as well).
I am looking for some pointers to isolate the issue further.
I am assuming that the fault is most likely still with the Y-SUS and the Z-SUS is only half warm as its a black picture.
The logic board has one led flashing steadily and some others on.
Questions I have are:
1) Are all buffer IC's independent - i.e. I have removed the top two but am still expecting the lower two to function normally (I had it running with one off beforehand for a few months as hadn't got round to replacing it! so don't see this as an issue).
2) what voltages (roughly) should a DMM measure on the output of the Y-SUS - everything at present is around minus 120V w.r.t chassis which I wasn't expecting. Unfortunately I don't have a scope available that I trust at these voltages!.
Photo attached
Attached Files
