Hello everyone,
Recently my laptop died while charging.
Upon opening it I found that PU401 had a huge hole in it and it lifted the pad.
I removed the chip and started looking for shorts. I found out that both DC-in MOSFETs were pretty toasty so I desoldered them aswell (PQ311 and PQ312).
The short wasn't gone though so I had to dig into the hole left by the PU401 and separate the B+ vias going through ground plane (pic1).
I thought I was done but I decided to check other rails too and the +3VALW was shorted too (0.6ohm).
After going through the schematics I found U10 which is a load switch. The 5V part was fine but 3V rail was shorted.
After removing it too the resistance went up to 0.8ohm. I tried injecting voltage, starting at 0.1V.
While checking each IC with a thermal probe I found PU1201 was the only one warming up. After removing it the short was gone.
That chip is responsible for a 1.35VGSP rail and it seems fine.
I went ahead and checked the remaining power rails and I found that +1.8VALW had a ground resistance of only 0.4ohm with the probes compensated.
However PU601 responsible for that railseemed fine and when disconnecting the PJ601 jumper I fount that the short is on a receiving end. I carefully applied voltage to that rail, starting again at 0.1V
Now the current was pretty high and I guess that's to be expected on such a low voltage rail.
At 0.5V I was drawing about 3A. And the only part that heated up was the CPU.
That was very worrying, but I still checked if other parts heated up or not, and then I noticed the current going down slowly.
All the heat was coming from the GPU die, but it seemed that some of it was coming from the bottom of the chip as well.
At this point I'm at a loss. Did I kill the CPU? Right now it shows the resistance of about 0.65 ohms on the 1.8V rail and I draw about 1.6A at 1V while injecting.
The 3V rail shows me the resistance of 15 ohms, but that's with some of the power hungry chips removed. Upon probing it draws about 100mA at 1V
So now the big queston is is it even worth trying to fix the hole in the board and replace all of those chips? Or is the CPU dead for sure and I should buy a new one?
This is my first laptop motherboard repair, so I'm unsure whether this behaviour is correct or not.
All help is appreciated
Recently my laptop died while charging.
Upon opening it I found that PU401 had a huge hole in it and it lifted the pad.
I removed the chip and started looking for shorts. I found out that both DC-in MOSFETs were pretty toasty so I desoldered them aswell (PQ311 and PQ312).
The short wasn't gone though so I had to dig into the hole left by the PU401 and separate the B+ vias going through ground plane (pic1).
I thought I was done but I decided to check other rails too and the +3VALW was shorted too (0.6ohm).
After going through the schematics I found U10 which is a load switch. The 5V part was fine but 3V rail was shorted.
After removing it too the resistance went up to 0.8ohm. I tried injecting voltage, starting at 0.1V.
While checking each IC with a thermal probe I found PU1201 was the only one warming up. After removing it the short was gone.
That chip is responsible for a 1.35VGSP rail and it seems fine.
I went ahead and checked the remaining power rails and I found that +1.8VALW had a ground resistance of only 0.4ohm with the probes compensated.
However PU601 responsible for that railseemed fine and when disconnecting the PJ601 jumper I fount that the short is on a receiving end. I carefully applied voltage to that rail, starting again at 0.1V
Now the current was pretty high and I guess that's to be expected on such a low voltage rail.
At 0.5V I was drawing about 3A. And the only part that heated up was the CPU.
That was very worrying, but I still checked if other parts heated up or not, and then I noticed the current going down slowly.
All the heat was coming from the GPU die, but it seemed that some of it was coming from the bottom of the chip as well.
At this point I'm at a loss. Did I kill the CPU? Right now it shows the resistance of about 0.65 ohms on the 1.8V rail and I draw about 1.6A at 1V while injecting.
The 3V rail shows me the resistance of 15 ohms, but that's with some of the power hungry chips removed. Upon probing it draws about 100mA at 1V
So now the big queston is is it even worth trying to fix the hole in the board and replace all of those chips? Or is the CPU dead for sure and I should buy a new one?
This is my first laptop motherboard repair, so I'm unsure whether this behaviour is correct or not.
All help is appreciated
Attached Files
