Acer Predator - no power

[survivalbloke]

Acer Predator Helios 300
Model PH315-54-748Y
SN: NHQC5AA0011440BA443400
Board GH51G LA-L181P Rev 1B

I've got 19.5 into 1st and second mosfet, but only 18.96 out of the second mosfet. Also, the GPU rail shows 0.6ohms resistance to ground, which seems low. I'm very curious as to why I have a voltage drop after the second mosfet. Thoughts where to look? When connected to power supply, it will start drawing 16ma, then after a few seconds it will drop to 0, then alternate between 0 and 2ma every couple of seconds.

https://imgur.com/a/GvIdrof

[Sephir0th]

These are way too less informations for a meaningful approach.

Recent mid- and highend GPU are absolutely supposed to measure low as 0.6 Ohms to GND and even lower on the Core Rail. So this doesn't mean anything.

Gate voltage of the DC-IN Mosfets (alternatively resistance between Source & Drain and between Source & Gate) and the resistance to GND of the Main power rail should be checked to have something like a useful start.

[alfredposadas08]

Acer Predator Helios 300
Model PH315-54-748Y
SN: NHQC5AA0011440BA443400
Board GH51G LA-L181P Rev 1B

I've got 19.5 into 1st and second mosfet, but only 18.96 out of the second mosfet. Also, the GPU rail shows 0.6ohms resistance to ground, which seems low. I'm very curious as to why I have a voltage drop after the second mosfet. Thoughts where to look? When connected to power supply, it will start drawing 16ma, then after a few seconds it will drop to 0, then alternate between 0 and 2ma every couple of seconds.

https://imgur.com/a/GvIdrof

check the 1st and 2nd mosfets gate voltages

[alfredposadas09]

Acer Predator Helios 300
Model PH315-54-748Y
SN: NHQC5AA0011440BA443400
Board GH51G LA-L181P Rev 1B

I've got 19.5 into 1st and second mosfet, but only 18.96 out of the second mosfet. Also, the GPU rail shows 0.6ohms resistance to ground, which seems low. I'm very curious as to why I have a voltage drop after the second mosfet. Thoughts where to look? When connected to power supply, it will start drawing 16ma, then after a few seconds it will drop to 0, then alternate between 0 and 2ma every couple of seconds.

https://imgur.com/a/GvIdrof

try to check the 1st mosfets its common that mosfet short , just replace it

[survivalbloke]

These are way too less informations for a meaningful approach.

Recent mid- and highend GPU are absolutely supposed to measure low as 0.6 Ohms to GND and even lower on the Core Rail. So this doesn't mean anything.

Gate voltage of the DC-IN Mosfets (alternatively resistance between Source & Drain and between Source & Gate) and the resistance to GND of the Main power rail should be checked to have something like a useful start.

Thank you for the information, especially the knowledge of resistance for the GPU. I found gate voltage to be equal to input voltage. I then checked resistance and discovered 1st mosfet shorted. Replaced it, and now the board is alive, with 25v on both gates. Thanks!

[survivalbloke]

try to check the 1st mosfets its common that mosfet short , just replace it

This was the problem! Thanks!