Acer A515-52 LA-G521P EH5AW

[DrFalken]

Hi guys !
this laptop came yesterday because turns on but won't POST, only a black screen and CPU becomes a little hot.
After usual checks (RAM, PSU, CMOS reset, caps discharge...) I've removed the M/B and find these:

• PQZ1 exploded: half onboard, half stuck on keyboard...
• a hole in PUZ2

(see attached pics)
Both have been removed.
+VCC_CORE looks a short to GND (what resistance to GND should measure ?)

PQZ2, PQZ3 & PQZ4 have been removed and checked against shorts (S-G, S-D, G-D).

The following have been checked working:
- PC9100
- PC9101
- PC9102

What else can I check before replacing PQZ1 & PUZ2 ?

Thank you

[piernov]

Re: Acer A515-52 LA-G521P EH5AW

99% chance CPU will be dead, better not waste time.

[DrFalken]

Re: Acer A515-52 LA-G521P EH5AW

99% chance CPU will be dead, better not waste time.

Nothing more to check ?

Right after removing bottom case (so dead PQZ1 & PUZ2 were still soldered), I've measured about 0.7V @VCC_CORE...is there a chance CPU can still be working ?

[mcplslg123]

Re: Acer A515-52 LA-G521P EH5AW

Was that a dual mosfet or high side mosfet?? If yes, SOC is gone as @piernov has already advised.

[DrFalken]

Re: Acer A515-52 LA-G521P EH5AW

Was that a dual mosfet or high side mosfet?? If yes, SOC is gone as @piernov has already advised.

PUZ2 is a dual mosfet driver
PQZ1 is a high side mosfet

Can I inject a very low voltage (ie starting from 0.5-0.6V) on VCC_CORE to check if SOC is really shorted or (maybe) some caps on the other side (see pics) ?

Thank you !

[mcplslg123]

Re: Acer A515-52 LA-G521P EH5AW

You can but perhaps waste of time. Have seen such damage on many many boards. So move on.

[DrFalken]

Re: Acer A515-52 LA-G521P EH5AW

You can but perhaps waste of time. Have seen such damage on many many boards. So move on.

Tried injecting the following voltages on VCC_CORE:

• 0.6V @ 1A -> 0.4V (VCC_VCORE multimeter reading)
• 0.75V @ 1.5A -> 0.5V
• 0.9V @ 2A -> 0.67V

At 0.9V@2A SOC started to heat up a little bit (barely detectable with the finger)

[mcplslg123]

Re: Acer A515-52 LA-G521P EH5AW

What are you upto??When you apply voltage at vcore, its natural for cpu to heat up.

[DrFalken]

Re: Acer A515-52 LA-G521P EH5AW

What are you upto??When you apply voltage at vcore, its natural for cpu to heat up.

I'm trying to check if CPU/SOC is dead or the short is caused by caps on the other side.

[mcplslg123]

Re: Acer A515-52 LA-G521P EH5AW

Its dead already, so keep on experimenting to satisfy your qwery.

[DrFalken]

Re: Acer A515-52 LA-G521P EH5AW

PQZ1 & PUZ2 replaced
VCC_Core = 0.79V

Timeline:
- 0: push power button, no display, power led turn blue, fan spin
- 5s: fan turn off
- 22s: power led turn off
- 26s: power led turn blue, fan spin
- 32s: fan turn off
- 60s: the SOC become hot, fan turn on and doesn't turn off anymore

SOC RIP ?

[vannix]

Re: Acer A515-52 LA-G521P EH5AW

i have a customer with the same motherboard (i7-8th + mx150) and the same situation in a notebook that does not boot after he take a flight with the computer packed in the luggage.
All.voltages are ok. No short, nothing heat except cpu.
Moving the ram module in the other slot it power on and off every 3 secs for 10 Times.
Reading your thread i'm also suspecting in bad cpu/soc

[mon2]

Re: Acer A515-52 LA-G521P EH5AW

Remove all peripherals / SSD / hard drive / RAM module(s).

Do you hear any memory missing beeps upon power up ?

[vannix]

Re: Acer A515-52 LA-G521P EH5AW

Remove all peripherals / SSD / hard drive / RAM module(s).

Do you hear any memory missing beeps upon power up ?

Nothing
Only blue led on

[mon2]

Re: Acer A515-52 LA-G521P EH5AW

From the schematic -> appears that the BLUE led is from the battery ?

Can you remove or disconnect the battery and attempt the same power up with the official known good power adapter ?

Also, with the adapter (only) check the DCIN mosfets which are often a root cause of all evil.

Perhaps baggage X-rays nuked the bios but too early to tell (although they claim they are safe to electronic equipment). The bios will then have to be reflashed.

See attached -> measure the voltage at the referenced checkpoints. Post the readings.

[vannix]

Re: Acer A515-52 LA-G521P EH5AW

From the schematic -> appears that the BLUE led is from the battery ?

Can you remove or disconnect the battery and attempt the same power up with the official known good power adapter ?

Also, with the adapter (only) check the DCIN mosfets which are often a root cause of all evil.

Perhaps baggage X-rays nuked the bios but too early to tell (although they claim they are safe to electronic equipment). The bios will then have to be reflashed.

See attached -> measure the voltage at the referenced checkpoints. Post the readings.

The bios reflash has been the 1st test. Without success..
Battery is disconnected. It has 2 leds, power (blue), battery (blue / orange). The battery charger circuit seems ok. Battery charges normally. And with battery or with dc i get the same result.
Tomorrow i'll post all voltage measurement

[mon2]

Re: Acer A515-52 LA-G521P EH5AW

Not an expert on this but the KBC KB9022 also features an internal flash memory. Perhaps this internal firmware (8051 based code) has been corrupted. From my limited knowledge on this topic, the main BIOS I believe is able to reflash the KB9022 but wait on advice from others. Just a FYI.

[DanielDacko]

Re: Acer A515-52 LA-G521P EH5AW

PQZ1 shot 19v straight to the cpu and killed it, you are milking a dead cow, don't waste time anymore.

[vannix]

Re: Acer A515-52 LA-G521P EH5AW

Not an expert on this but the KBC KB9022 also features an internal flash memory. Perhaps this internal firmware (8051 based code) has been corrupted. From my limited knowledge on this topic, the main BIOS I believe is able to reflash the KB9022 but wait on advice from others. Just a FYI.

To be sure i can try to reflash it
https://www.badcaps.net/forum/showpo...13&postcount=8

[mon2]

Re: Acer A515-52 LA-G521P EH5AW

Sounds good but do also check the resistance to ground of the VCC_CORE rail. Remove all power -> meter in resistance mode -> post the reading to confirm the CPU is still ok.