Hello,
I'm looking for pointers/ideas to find what's wrong with the motherboard of my Lenovo Thinkpad P50.
Motherboard: BP500, NM-A451, VER 1.0
Schematics & Boardview: https://www.badcaps.net/forum/showth...hlight=NM-A451
Here is what I know up to now:
The computer was never in contact with liquid, nor dropped.
It suddenly lost power while I was working. It was attached to the docking station, with the battery inside. Not any lights or other sign of life when I try to power on. The LED of the DC-in jack does not light up.
The charger and the battery do provide adequate voltage.
I tried to fully reset the BIOS' by removing the CMOS battery and I tried power on with only the battery and only the charger.
I discovered that the CMOS battery was dead (near 0 V); I bought a new one, but it does not solve the issue.
I attached a 3V battery and measured a current draw of ~2.5 mA (off state), which seems huge to me considering that at this rate it would be empty in 3 days. Does it provide any hint?
Visually, I do not see a problem on the board. There are some stains here and there, as illustrated in red in the attached picture, but I suppose it is just flux from manufacturing.
I started measuring voltages and looking at continuity, thanks to the schematic and boardview. I removed all components except the fans and heat-pipes before measuring. The CMOS battery is not attached either. Should I attach it?
VINT20 is OK everywhere I measured it. VREGIN20 is OK at R515 and R516.
VCC3MP and VCC5MP are also OK at the output of the converters (coils).
I got no voltage for VCC3M(P) at PR64.
I measured ~3.3 V for VCC3SW at several locations, but I got no voltage at R526, R529, PR256, PR257, PR295. I suppose it's not normal but I'm not sure.
From here, I'm uncertain how to proceed further in an effective way to find the source of the problem.
I had a course of electronics at university several years ago, but I'm not an electronics engineer or technician. It's the first time I tinker with a board.
Thank you for any advice.
I'll gladly provide any further info. Later, I'll post a picture of the board with what I measured.
I'm looking for pointers/ideas to find what's wrong with the motherboard of my Lenovo Thinkpad P50.
Motherboard: BP500, NM-A451, VER 1.0
Schematics & Boardview: https://www.badcaps.net/forum/showth...hlight=NM-A451
Here is what I know up to now:
The computer was never in contact with liquid, nor dropped.
It suddenly lost power while I was working. It was attached to the docking station, with the battery inside. Not any lights or other sign of life when I try to power on. The LED of the DC-in jack does not light up.
The charger and the battery do provide adequate voltage.
I tried to fully reset the BIOS' by removing the CMOS battery and I tried power on with only the battery and only the charger.
I discovered that the CMOS battery was dead (near 0 V); I bought a new one, but it does not solve the issue.
I attached a 3V battery and measured a current draw of ~2.5 mA (off state), which seems huge to me considering that at this rate it would be empty in 3 days. Does it provide any hint?
Visually, I do not see a problem on the board. There are some stains here and there, as illustrated in red in the attached picture, but I suppose it is just flux from manufacturing.
I started measuring voltages and looking at continuity, thanks to the schematic and boardview. I removed all components except the fans and heat-pipes before measuring. The CMOS battery is not attached either. Should I attach it?
VINT20 is OK everywhere I measured it. VREGIN20 is OK at R515 and R516.
VCC3MP and VCC5MP are also OK at the output of the converters (coils).
I got no voltage for VCC3M(P) at PR64.
I measured ~3.3 V for VCC3SW at several locations, but I got no voltage at R526, R529, PR256, PR257, PR295. I suppose it's not normal but I'm not sure.
From here, I'm uncertain how to proceed further in an effective way to find the source of the problem.
I had a course of electronics at university several years ago, but I'm not an electronics engineer or technician. It's the first time I tinker with a board.
Thank you for any advice.
I'll gladly provide any further info. Later, I'll post a picture of the board with what I measured.
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