ACER E5-574G shuts down after 1 second

[damatg]

Dear all,
I'm trying to repari an ACER E5-574G that shuts down after 1 second.

The notebook shows the charging light when connected to the power adapter.
When powered on the fan starts spinning and the led indicator is on, but after just one second a click sound (even when all mechanical components are disconnected, including the fan) can be heard and the notebook shuts down.

When the notebook is powered on without RAM banks, it stays on indefinitely (USB ports are powered).

I tested the PUs and it seems that PU6&PU7 outputs (+VCCGT) are always 0v, whereas the output of the other PUs seems correct.

It seems to me that +VCCGT rail is shorted, I read 3ohm (with respect to chassis ground) if I probe a ground near PU6 and its output.

Please suggest me what I can do (maybe voltage injection?) to find the fault.

Thank you,
Giulio

[damatg]

Re: ACER E5-574G shuts down after 1 second

Update:
I checked the resistance between GND and +VCCGT and it was 0 ohm.

This morning I desoldered the PU6 and PU7 coils and resistance at +VCCGT was around 6 ohm (which seems reasonable).

At the other side of the coil, PU7 seemed OK and PU6 seemed KO with 0 ohm to GND.
I desoldered PU6 and expected to find a short between its output and GND but this was not the case.

I resoldered everything back in place and the short was not there anymore.
However, the problem is still there, nothing changed.

Then, I tried to inject 1V at +VCCGT and no odd current draw could be detected (current was below 1A). Nothing became hot.

Any suggestion?

[mcplslg123]

Re: ACER E5-574G shuts down after 1 second

What is the mb code?? Without ram it stays on-have you checked the ram circuit properly?? The ram stick is known good?? There is no corrosion near ram circuit??

[damatg]

Re: ACER E5-574G shuts down after 1 second

hi, thank you for your answer.

MB code is: DA0ZRWMB6G0 REV:G

ram circuit has no corrosion, ram sticks seem good.
+1.35VSUS is present, but I'll check again with oscilloscope and RAM present.