Asus Predator Helios 300 Laptop - No power

[sawuk]

Make: Asus Predator Helios 300
Model: N20C3
MFG date: 20/4/2021
S/N: NHQATEK001116068A83400

Motherboard model: GH51M LA-K862P Rev: 1A 2020-12-23

Issue: Motherboard has no power, no charging light with charger plugged in and will not turn on with power button. Customer states Laptop went off all of a sudden with no warning.

I have tried another charger and still does not work, customer confirmed that original charger works in another laptop of the same make and model.

I then removed the components (RAM and SSD's) and still no power.

I have removed the motherboard and tested the output of the DC IN jack on the board with the Charger connected and get 0.2V.

I tested the charger before inserting into the laptop and get 19.8V. When the charger has been inserted into the laptop it trips the charger out.

When I take the charger out I get a reading fluctuating between 0.1V and 0.4V from the charger tip. When the charger has been disconnected from the mains and left for about 10 seconds, I plug it back into the mains and test it, I get 19.8V back again.

Anybody got any ideas on what it may be, or what I can do to try and diagnose it?

[mon2]

Hello. Yes, review the dcin mosfets and the sticky above on charger circuits by piernov.

[DeXXter]

Check resistance on 19v line, it looks like the first mosfet are blocking the power.

[sawuk]

Hello. Yes, review the dcin mosfets and the sticky above on charger circuits by piernov.

Thanks, I can't see the sticky when clicking the link. Only the users profile.

[sawuk]

Check resistance on 19v line, it looks like the first mosfet are blocking the power.

Hi, thanks for responding. Sorry for the late reply work commitments have prevented me from checking this.

I am new to PCB repairs so bare with me. When checking each pin of the first MOSFET from the DCIN I am getting readings of close to 600 Ohms in diode mode on the multimeter. Does that sound correct?

[rogfanther]

Use the multimeter in resistance mode.

[sawuk]

Use the multimeter in resistance mode.

Every pin gives me a value then immediately goes to 1 on the multimeter. I am using red probe on GND and red probe on each MOSFET pin.

I have struggled to find the correct openboardview file for this motherboard