Asus GA401QM dead, no lights.

[jacobtc]

Re: Asus GA401QM dead, no lights.

No offense, but something must be wrong with the probes our your multimeter. From typical design of these boards, the 5 most left coils are for GPU Core and I wouldn't expect really more than 1 Ohms to GND there. 5 coils to the right should be related to CPU but maybe different rails in addition.

Someone should correct me otherwise.

Edit: Screw hole might be okay, but pay attention to proper contact. One side of each coil is enough, since they're basically a "wire".

Yeah, did I mention I might sound like an idiot? I had my meter in a weird range, just redid the measurements, the five ones on the left are 0.3 Ohm, the first four on the right are 5.7 Ohm, the very last coil only measures 0.17 Ohm... woops
This is the reading from my MM, my leads measure 0.10-0.12 ohm.
See attached.

[jacobtc]

Re: Asus GA401QM dead, no lights.

Short the probes on your meter. What is the resistance that is shown ? It should be ~0 ohms.

You are right, my probes are 0.12 ohms, I had a brainfart and did the measurements with a wrong scale, redid the measurements, and the five ones on the left are 0.3 Ohm, the first four on the right are 5.7 Ohm, the very last coil only measures 0.17 Ohm.

[Sephir0th]

Re: Asus GA401QM dead, no lights.

Sorry to tell that, but that's likely a dead CPU then. you could check whether the resistance raises or not when Lifting the related coil (the one with 0.17 Ohms) or removing the DrMOS.

[jacobtc]

Re: Asus GA401QM dead, no lights.

Sorry to tell that, but that's likely a dead CPU then. you could check whether the resistance raises or not when Lifting the related coil (the one with 0.17 Ohms) or removing the DrMOS.

Yeah I feared that.
I took the coil off, and the resistance did not change, but is now 3.5 kOhm on the other side. See attached.
Did not remove DrMOS yet.

EDIT: Removed the DrMos, no change

[aldairelme]

Re: Asus GA401QM dead, no lights.

Yes, I know I had a similar laptop I fixed a while ago, don't blame me for picking up a new (dead) one

This one shows no life with AC or USB-C charging. Reset CMOS, removed battery, and tried again, nothing. No lights, and no response when power on button is pressed.

Measured DC In mosfets as good, and the board seemingly seems to supply 20V, 5V and 1.2V with my quick measurements. Battery is completely depleted, I believe this has disabled itself as my other battery also did. When DC is plugged in the GPU gets 45C and CPU VRM/Mosfets get to same temperature. CPU itself is cold.

No immediate shorts on the board as I could find, but will need to dig deeper later.

Coils at CPU area measure 30-40ohm.

The laptop is shipped with liquid metal on the CPU, and the cooler screws had been used, so the first thing I checked was for any leakage of the LM on the board, but I haven't found any.

I have attached some pictures of the board.

What would be the correct way to tackle this board? Haven't had a board with no immediate short to correct.

heey!...I had exactly the same problem.
no leds, no fans, connecting DC heated up the GPU but not the CPU.

and reviewing the liquid metal of the processor I found this.

(remove all the white silicone to see if you have figs like me).

and turned on without problems.

[nissimezra]

Re: Asus GA401QM dead, no lights.

Hi friends
I have 4v on the output of the 2nd mosfet (main power 19v), I fixed one with the same issue, it was dual diode supplying VCC to the BQ, I don't have schematic and I can't find the dual diode. Anyone know where this dual diode is?

[mon2]

Re: Asus GA401QM dead, no lights.

Which charger IC is onboard? BQ series?

Post clear pics of that region for a review.

Next, remove all power. Meter in resistance mode.

Measure the resistance to ground of the main power rail that will be the output of the 2nd mosfet. Checking if it is a low resistance reading which will cause a voltage drop.

Also measure the voltage to ground of pin #4 (gate pins) of the DCin mosfets.

These gate pins will be driven by the ACDRV pin of the charger IC, if BQ series.

[nissimezra]

Re: Asus GA401QM dead, no lights.

Which charger IC is onboard? BQ series?

Post clear pics of that region for a review.

Next, remove all power. Meter in resistance mode.

Measure the resistance to ground of the main power rail that will be the output of the 2nd mosfet. Checking if it is a low resistance reading which will cause a voltage drop.

Also measure the voltage to ground of pin #4 (gate pins) of the DCin mosfets.

These gate pins will be driven by the ACDRV pin of the charger IC, if BQ series.

Many thanks for your help
bq
The resistance on the main power is high in the mega ohm the same on the gates of the mosfet. if the battery charged the laptop work, these laptops will not work without the battery, bypassing the mosfets the laptop will not power on.
there is low vcc on the bq chip 4.5 volt. there should be dual diode one pin from the battery one pin from the charger, it suplly vcc to the BQ24800 Chip

[nissimezra]

Re: Asus GA401QM dead, no lights.

Which charger IC is onboard? BQ series?

Post clear pics of that region for a review.

Next, remove all power. Meter in resistance mode.

Measure the resistance to ground of the main power rail that will be the output of the 2nd mosfet. Checking if it is a low resistance reading which will cause a voltage drop.

Also measure the voltage to ground of pin #4 (gate pins) of the DCin mosfets.

These gate pins will be driven by the ACDRV pin of the charger IC, if BQ series.

this chip apl6012 on the back of BQ

[mon2]

Re: Asus GA401QM dead, no lights.

See attached.

[jacobtc]

Re: Asus GA401QM dead, no lights.

Many thanks for your help
bq
The resistance on the main power is high in the mega ohm the same on the gates of the mosfet. if the battery charged the laptop work, these laptops will not work without the battery, bypassing the mosfets the laptop will not power on.
there is low vcc on the bq chip 4.5 volt. there should be dual diode one pin from the battery one pin from the charger, it suplly vcc to the BQ24800 Chip

Not correct, I've had a couple that worked without battery.

[nissimezra]

Re: Asus GA401QM dead, no lights.

See attached.

Thank you
2.5v on the anode and 0 katode
4.7 ohm resistor good

[nissimezra]

Re: Asus GA401QM dead, no lights.

I was thinking if I can't find the diode just to add diode from the charge, it should work

[mon2]

Re: Asus GA401QM dead, no lights.

See attached. TI appears to be hiding the datasheet for this charger IC.

Only the blessed few can buy this part.

This schematic is from their EVM kit.

Pin #28 is the Vcc for the charger IC. So the guess is correct but the voltage readings are not ok.

Can you confirm how you measured these last values?

Meter in 20V or higher DC volts scale.

Attach the power adapter.

Red meter probe on pin #28 (right side of the diode marked ED).
Black meter probe to ground.

This voltage is powering this charger IC and it should be ~19 volts on a working board.

What do you read? Also check with the red meter probe on the LEFT side of the 'ED' diode.

Post each measurement.

[nissimezra]

Re: Asus GA401QM dead, no lights.

See attached. TI appears to be hiding the datasheet for this charger IC.

Only the blessed few can buy this part.

This schematic is from their EVM kit.

Pin #28 is the Vcc for the charger IC. So the guess is correct but the voltage readings are not ok.

Can you confirm how you measured these last values?

Meter in 20V or higher DC volts scale.

Attach the power adapter.

Red meter probe on pin #28 (right side of the diode marked ED).
Black meter probe to ground.

This voltage is powering this charger IC and it should be ~19 volts on a working board.

What do you read? Also check with the red meter probe on the LEFT side of the 'ED' diode.

Post each measurement.

Many thanks
There is no VCC from charger only from the battery
I dragged a wire from the input of the charger 20v via diode to pin 28 vcc. The laptop turn on but black screen. Looks like no vcore

[nissimezra]

Re: Asus GA401QM dead, no lights.

See attached. TI appears to be hiding the datasheet for this charger IC.

Only the blessed few can buy this part.

This schematic is from their EVM kit.

Pin #28 is the Vcc for the charger IC. So the guess is correct but the voltage readings are not ok.

Can you confirm how you measured these last values?

Meter in 20V or higher DC volts scale.

Attach the power adapter.

Red meter probe on pin #28 (right side of the diode marked ED).
Black meter probe to ground.

This voltage is powering this charger IC and it should be ~19 volts on a working board.

What do you read? Also check with the red meter probe on the LEFT side of the 'ED' diode.

Post each measurement.

look what happen on the cpu. liquid metal leaked out
thats why no vcore

[nissimezra]

Re: Asus GA401QM dead, no lights.

Not correct, I've had a couple that worked without battery.

You are right it is working without battery