Dead ASUS ROG G14 (GA401)

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Yes, with the adapter connected.

After the voltage check, remove all power.

Measure the resistance of the same mosfet:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement.

Here you go.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Yes, with the adapter connected.

After the voltage check, remove all power.

Measure the resistance of the same mosfet:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Post each measurement.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Measure the voltage to ground readings of the first mosfet.

Post each measurement.

So with AC connected?

[mon2]

Re: Dead ASUS ROG G14 (GA401)

I also missed the low voltage on pin # 3 (CMSRC). Mosfet # 1 is a suspect.

Attached is a typical hookup of this charger IC.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Measure the voltage to ground readings of the first mosfet.

Post each measurement.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Before you proceed..check that there are no shorts on the source, gate or drain pins on the PCB pads.

No shorts on pads. Soldered new mosfet, no change. Still same 4V out, and 0V on Pin 10.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Before you proceed..check that there are no shorts on the source, gate or drain pins on the PCB pads.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

What are the topside markings of this mosfet?

Being n-channel, you can probably replace it with many others on donor boards, etc.

First, need to be sure there is a physical match.
2nd - the mosfet is N-channel.
3rd - current / voltage support.

If you have donor boards around - check if the charger IC is any of the BQ series. The BQ charger ICs use N-channel mosfets.

It is a M3058M, I have a couple of those laying around as well

[mon2]

Re: Dead ASUS ROG G14 (GA401)

What are the topside markings of this mosfet?

Being n-channel, you can probably replace it with many others on donor boards, etc.

First, need to be sure there is a physical match.
2nd - the mosfet is N-channel.
3rd - current / voltage support.

If you have donor boards around - check if the charger IC is any of the BQ series. The BQ charger ICs use N-channel mosfets.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Pin 10 voltage on the charger IC is of concern.

See attached.

Can you remove the 2nd DCin mosfet? Then measure the resistance of the removed part while it is on your work table.

Intered in the resistance readings of the removed mosfet between:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

Just did S-D, and that measures a dead short... Jesus, these are hard to find. I did voltage injection, although only 1V1A, but still, that did not show up on the thermal image...

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Pin 10 voltage on the charger IC is of concern.

See attached.

Can you remove the 2nd DCin mosfet? Then measure the resistance of the removed part while it is on your work table.

Intered in the resistance readings of the removed mosfet between:

source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Got some voltages for ya'

Wouldn't the voltage only tank if something was connected? I have everything disconnected when doing the measurements...

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Perhaps some other component is causing the main power rail to tank.

You can check the resistance to ground of the main power rail but without power of course.

Check it without the display -> then with the display. If the current sense by the charger IC is that there is an excessive current draw, the DCin mosfets will be instructed to shut off.

Do not connect the battery at this stage of testing - only the power adapter. Need to be sure that the video and normal boot cycle is working.

Sorry, actually the display was not connected. The laptop was purchased with a broken display as well, so I only connected the display cable to the motherboard, the other end was not connected to a display.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Perhaps some other component is causing the main power rail to tank.

You can check the resistance to ground of the main power rail but without power of course.

Check it without the display -> then with the display. If the current sense by the charger IC is that there is an excessive current draw, the DCin mosfets will be instructed to shut off.

Do not connect the battery at this stage of testing - only the power adapter. Need to be sure that the video and normal boot cycle is working.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Sorry, I meant to measure the voltage to ground of each pin. Post the list again.

Need to check if the charger IC has the conditions to spit out the boosted voltage on ACDRV. Be sure that the part is well fluxed and well heated to swim but settle down on the PCB pads, naturally. Low air pressure but enough heat to make it swim. Just in case there are any shorts, this process will correct the hidden shorts.

Alright, I will remove and resolder the BQ IC and get new measurements tomorrow, it's bedtime for me

Thank you for your support!

EDIT: I also find it weird that the second mosfet did output 20V when I first replaced the BQ IC, but when I had it in the case, with display etc plugged in, nothing happened, and afterwards the mosfet measured 4V again.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Sorry, I meant to measure the voltage to ground of each pin. Post the list again.

Need to check if the charger IC has the conditions to spit out the boosted voltage on ACDRV. Be sure that the part is well fluxed and well heated to swim but settle down on the PCB pads, naturally. Low air pressure but enough heat to make it swim. Just in case there are any shorts, this process will correct the hidden shorts.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

I just moved it, so it only had one pad connected. I have not removed it completely, no change.

I did the requested readings, see pic.

I still find it weird that the first DC-IN mosfet has 20V in, 0V out, then the next mosfet has 0V in and 4V out.. How is that possible?

[mon2]

Re: Dead ASUS ROG G14 (GA401)

I am not clear on the operation done here on this resistor.

Can you just hot air the part and remove it? Do not lose the part.

Then we are sure the part is not being loaded down on the ACDRV pin.

If you still do not gain back the 25v on ACDRV pin, then with care, measure each pin on the charger IC to ground.

Post the readings for a review.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Moved the resistor, still no change (0V on Pin 4).

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Yes. Very likely that you will get back your 25v on ACDRV pin #4 but confirm it.

Then the suspect is the 2nd DCin mosfet. It is probably defective and must be replaced.