Acer swift SF514-51-74X1 Compal LA-D591P Freezing on boot

[jkboard]

Hi,

Few months ago I got a faulty Acer swift laptop. Original fault: No power, not charging. I found out, that a MLCC (PC303) was shorted to ground at charging circuit HIDRV fet (PQ305). During troubleshooting I broke other fet (PQ306) in half when removing it.

I replaced both fets at the charging side, (PQ305, PQ306) and the shorted cap (PC303). Laptop booted with AC power, but still not charging. I ordered charging IC (PU301). While waiting for new IC, I did a fresh install of win10 and ubuntu to a new nvme disk. Everything working ok, except not charging.

I got new charging IC replaced and the laptop is charging again. However I hassled with AC power connector and managed to touch +5VALW line at RG2 resistor with its metal casing burning the trace and killing the +5V rail. I replaced PU402 to fix this.

Now I have a laptop that freezes when OS graphics kick in. That is, when ubuntu circle starts to roll (live usb). Similar results with win10 usb. When freezing happens, VCC_CORE drops from 1,15V to 0,73V and VCC_GT goes from 0V to 0,64V for about one second, then back to zero. Other voltage rails appear to be ok. I replaced PU8101 with no effect. Now I'm open for hints and advice. jk

[MOD EDIT] Link to schematic & boardview - https://www.badcaps.net/forum/showthread.php?t=126095
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[qayyum786]

Re: Acer swift SF514-51-74X1 Compal LA-D591P Freezing on boot

1st change VCC_CORE high and low mosfet
if still same replace clock ic

[jkboard]

Re: Acer swift SF514-51-74X1 Compal LA-D591P Freezing on boot

When VCC_CORE drops from 1,15V to 0,73V, it drops because pwm duty cycle driving the fet from PU8101 drops. So I think the fet is fine.
What you mean by clock ic?

[jkboard]

Re: Acer swift SF514-51-74X1 Compal LA-D591P Freezing on boot

So I replaced PQ8201 (+VCC_GT) and PQ8202 (+VCC_CORE) mosfets. Symptoms are still the same.

Is there any testing software I could try to troubleshoot this? I have run Pc-Check V6.21 and all tests pass except DMA Controller Tests and System Timer Tests. This is however quite old version of pc check, and I have run it on other working laptops with those two tests failing.

What happens, when OS logo appears and system hangs?

[jkboard]

Re: Acer swift SF514-51-74X1 Compal LA-D591P Freezing on boot

Spent few hours testing this laptop again. Still no idea what might cause VCC_CORE to drop from 1,15V to 0,73V. Drop is due to PU8101 PWM_1a duty cycle drop. What tells PU8101 duty cycle to decrease?

[Udemzy]

Re: Acer swift SF514-51-74X1 Compal LA-D591P Freezing on boot

When VCC_CORE drops from 1,15V to 0,73V, it drops because pwm duty cycle driving the fet from PU8101 drops. So I think the fet is fine.
What you mean by clock ic?

The 24mhz clock ic