Hello All,
I am trying to repair an old Abit ST6-R motherboard.
The symptoms are the following:
I got it in a non-working state. I was told that it sometimes turned on, but many times just the CPU fan was spinning and no other signs of life, the board didn't POST, and now it doesn't POST at all.
It was full of bulged electrolytic capacitors, so I replaced all of them with new Low-ESR ones, but it didn't solve the problem.
If I install a CPU in the S370 socket, only the fans are spinning and no POST. There are no beep codes even if the RAM DIMMs are unpopulated, and the CPU doesn't get hot at all even if I start it without a heatsink, it remains totally cold. Unfortunately I don't have a POST analyzer card.
I suspect that the 55N03LTA MOSFETs that are near the CPU sockets are toast and was probably killed by the faulty caps with overcurrent probably. I measured their leg's voltage to ground while a known good Pentium III 733MHz CPU was seated in the socket. I have attached aphotos from my measurements.
I would like some suggestions, on how to test them, and if they are really gone, do you guys have any recommendations for replacement parts that are still available in the EU?
Can you please help me in repairing this board?
Thank you.
I am trying to repair an old Abit ST6-R motherboard.
The symptoms are the following:
I got it in a non-working state. I was told that it sometimes turned on, but many times just the CPU fan was spinning and no other signs of life, the board didn't POST, and now it doesn't POST at all.
It was full of bulged electrolytic capacitors, so I replaced all of them with new Low-ESR ones, but it didn't solve the problem.
If I install a CPU in the S370 socket, only the fans are spinning and no POST. There are no beep codes even if the RAM DIMMs are unpopulated, and the CPU doesn't get hot at all even if I start it without a heatsink, it remains totally cold. Unfortunately I don't have a POST analyzer card.
I suspect that the 55N03LTA MOSFETs that are near the CPU sockets are toast and was probably killed by the faulty caps with overcurrent probably. I measured their leg's voltage to ground while a known good Pentium III 733MHz CPU was seated in the socket. I have attached aphotos from my measurements.
I would like some suggestions, on how to test them, and if they are really gone, do you guys have any recommendations for replacement parts that are still available in the EU?
Can you please help me in repairing this board?
Thank you.
.
Comment