Hey guys, grateful if you can help me figure out issue with the following:
Board reference: AAL15 LA-D071P rev 1.0 (with dGPU)
Backstory:
Laptop came in as dead. After diagnosis, 5VALW regulator was shorted. Regulator was replaced and laptop boots without issue.
However, when trying to boot into windows, I get WHEA_UNCORRECTABLE_ERROR and laptop reboots. Sometimes it would start booting into windows and give the welcome message (fresh windows installed) but would then give BSOD with above error and restart. Sometimes I get MEMORY_MANAGEMENT BSOD and sometimes PAGE_FAULT_IN_NONPAGED AREA.
Preliminary tests (with and without CMOS battery installed):
1. Swapped HDD with known good -> No change
2. Swapped RAM with known good and I get RAM error blink code (2 amber, 4 white)
3. Check RAM slot for debris/corrosion and broken solder joints -> No issue
4. Flash known good BIOS -> No change
Weird issue:
Referring to 2nd test mentioned above, if original RAM and my known good RAM is installed, it would sometime boot and detect properly. But if I use only my RAM, I get RAM error blink.
Voltage measurement
At first measurement, all voltage seemed OK but right when windows starts loading, the CPU core voltage is all over the place. At boot CPU is around 0.94V but as soon as windows starts loading, voltage can go as low as 0.6V.
Removing HDD and booting from USB (to prompt windows installation wizard) and causes fluctuating voltage as above.
Measuring +VCC_CORE with DSO shows a VERY noisy line.
The voltage on drops when windows starts loading. Otherwise it stays around 0.94V
What I did so far:
1. Replace output capacitors on CPU core -> No change.
2. Use slightly higher capacitance (220uF default, changed to 330uF) -> No change.
3. Check and redid solder joints of the whole CPU power section in case there is a dry joint -> No change.
4. Replaced inductor -> No change.
5. Swapped switch IC with +VCC_GT -> No change.
6. I don't have replacement IC for main CPU controller chip. Removed existing one to check for corrosion and redid solder joints just in case -> No change.
NOTE:
1. No change means still getting WHEA_UNCORRECTABLE_ERROR BSOD
2. DSO probe point -> Output of +VCC_CORE inductor
There is no corrosion on the board and all other voltages are stable and smooth. Am not sure what else to check. Could it be potentially cracked BGA solder of the SoC? Any Suggestion please?
Board reference: AAL15 LA-D071P rev 1.0 (with dGPU)
Backstory:
Laptop came in as dead. After diagnosis, 5VALW regulator was shorted. Regulator was replaced and laptop boots without issue.
However, when trying to boot into windows, I get WHEA_UNCORRECTABLE_ERROR and laptop reboots. Sometimes it would start booting into windows and give the welcome message (fresh windows installed) but would then give BSOD with above error and restart. Sometimes I get MEMORY_MANAGEMENT BSOD and sometimes PAGE_FAULT_IN_NONPAGED AREA.
Preliminary tests (with and without CMOS battery installed):
1. Swapped HDD with known good -> No change
2. Swapped RAM with known good and I get RAM error blink code (2 amber, 4 white)
3. Check RAM slot for debris/corrosion and broken solder joints -> No issue
4. Flash known good BIOS -> No change
Weird issue:
Referring to 2nd test mentioned above, if original RAM and my known good RAM is installed, it would sometime boot and detect properly. But if I use only my RAM, I get RAM error blink.
Voltage measurement
At first measurement, all voltage seemed OK but right when windows starts loading, the CPU core voltage is all over the place. At boot CPU is around 0.94V but as soon as windows starts loading, voltage can go as low as 0.6V.
Removing HDD and booting from USB (to prompt windows installation wizard) and causes fluctuating voltage as above.
Measuring +VCC_CORE with DSO shows a VERY noisy line.
The voltage on drops when windows starts loading. Otherwise it stays around 0.94V
What I did so far:
1. Replace output capacitors on CPU core -> No change.
2. Use slightly higher capacitance (220uF default, changed to 330uF) -> No change.
3. Check and redid solder joints of the whole CPU power section in case there is a dry joint -> No change.
4. Replaced inductor -> No change.
5. Swapped switch IC with +VCC_GT -> No change.
6. I don't have replacement IC for main CPU controller chip. Removed existing one to check for corrosion and redid solder joints just in case -> No change.
NOTE:
1. No change means still getting WHEA_UNCORRECTABLE_ERROR BSOD
2. DSO probe point -> Output of +VCC_CORE inductor
There is no corrosion on the board and all other voltages are stable and smooth. Am not sure what else to check. Could it be potentially cracked BGA solder of the SoC? Any Suggestion please?
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