Might have some liquid damage (from > 1 year ago, was completely fine until a month ago) - unable to notice anything wrong easily on the motherboard (Core i7, GPU MX250, UX481FLY). I have cleaned parts of the motherboard with some oxidation with solder and flux - did not help.
Laptop does turn on sometimes and is fully functional. However, while it is fully functional - (1) If rebooted, most of the times it enters a restart loop with blank screen (2) Sometimes, it crashes by itself and enters restart loop - with no relation to CPU/GPU load, heat, etc.
I found that If I remove the CPU/GPU heatsink and probe around the +VCCCORE power circuit with a multimeter - there is a higher chance of the laptop booting successfully.
From the attached schematic, I have verified that following are ok all the time:
+3VADSW/+5VSUS
5V supply for USB implying -> SUSC_EC is OK -> EC is ok
Battery charging circuit is ok - LED blinking + battery charging
I have not found anything wrong with all of the power rails I checked except for this - looking at page 57 of schematic PDF, there are 3 MOSFETs powering the +VCCCORE? And all of them should output voltage to the same rail (+VCCCORE)?
In the attached image of example motherboard, when the laptop boots properly (or does not power on), A has output of 0 V, B has around 0.85 V. I am not sure if this is normal, it does not make sense to me that if outputs of all these MOSFETs are tied why would point A be at 0V (I made sure to probe multiple points to make sure there is electrical contact between multimeter probe and the board).
Please help with any suggestions on how to do a better diagnosis of what is wrong! Thank you!
Schematic - https://www.badcaps.net/forum/troubl...tics-boardview
Laptop does turn on sometimes and is fully functional. However, while it is fully functional - (1) If rebooted, most of the times it enters a restart loop with blank screen (2) Sometimes, it crashes by itself and enters restart loop - with no relation to CPU/GPU load, heat, etc.
I found that If I remove the CPU/GPU heatsink and probe around the +VCCCORE power circuit with a multimeter - there is a higher chance of the laptop booting successfully.
From the attached schematic, I have verified that following are ok all the time:
+3VADSW/+5VSUS
5V supply for USB implying -> SUSC_EC is OK -> EC is ok
Battery charging circuit is ok - LED blinking + battery charging
I have not found anything wrong with all of the power rails I checked except for this - looking at page 57 of schematic PDF, there are 3 MOSFETs powering the +VCCCORE? And all of them should output voltage to the same rail (+VCCCORE)?
In the attached image of example motherboard, when the laptop boots properly (or does not power on), A has output of 0 V, B has around 0.85 V. I am not sure if this is normal, it does not make sense to me that if outputs of all these MOSFETs are tied why would point A be at 0V (I made sure to probe multiple points to make sure there is electrical contact between multimeter probe and the board).
Please help with any suggestions on how to do a better diagnosis of what is wrong! Thank you!
Schematic - https://www.badcaps.net/forum/troubl...tics-boardview
Attached Files
