Dead ASUS ROG G14 (GA401)

[mcplslg123]

Re: Dead ASUS ROG G14 (GA401)

It is absolutely safe to power a mb without EC. BGA EC's are mostly programmable thru JTAG but they are nightmare to program.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

It is absolutely safe to power a mb without EC. BGA EC's are mostly programmable thru JTAG but they are nightmare to program.

This will be programmed through the BIOS it seems.

[rediii]

Re: Dead ASUS ROG G14 (GA401)

This will be programmed through the BIOS it seems.

this is what i would say, too. i never reprogrammed the bga ite chips on asus laptops and if this ic was faulty replacing it resulted in a working machine...

[mcplslg123]

Re: Dead ASUS ROG G14 (GA401)

Agree, with Asus, ec is programmed from main bios on 1st boot. however, in other brands, its not always so.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Well! Just received the new EC.. Soldered it, and checked that the short was still gone (it is).
The laptop is still dead though, I still get 19V in to first DC-in mosfet, 0V out, next mosfet is 0V in, 4V out?

I could just go ahead and solder all new mosfets on the board, but I have the idea of working blind, and just throwing stuff at it until it might work.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

Start with the basics as per the above sticky by @Piernov.

1) Often the 2nd DCin mosfet gets killed.

2) Which charger IC is onboard? Likely the BQ series? Share the full topside markings of the charger IC.

3) Assuming it is the BQ series, the GATE pins of the 2 x DCin mosfets will be driven by the ACDRV pin.

This ACDRV pin must be ~25v to enable the N-channel mosfets.

Confirm the voltage to ground of the ACDRV pin.

Also check:

REGN
ACOK
ACDET

Post each measurement.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Start with the basics as per the above sticky by @Piernov.

1) Often the 2nd DCin mosfet gets killed.

2) Which charger IC is onboard? Likely the BQ series? Share the full topside markings of the charger IC.

3) Assuming it is the BQ series, the GATE pins of the 2 x DCin mosfets will be driven by the ACDRV pin.

This ACDRV pin must be ~25v to enable the N-channel mosfets.

Confirm the voltage to ground of the ACDRV pin.

Also check:

REGN
ACOK
ACDET

Post each measurement.

Thanks, you are always a great help!

The IC is a BQ24780S,
ACDRV (Pin 4) is 0V
REGN (Pin 24) is 0.4V
ACOK (Pin 5) is 0.4V
ACDET (Pin 6) is 2.7V

EDIT: And VCC (Pin 28) is present on IC at 19V.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

The IC is a BQ24780S,

ACDRV (Pin 4) is 0V
REGN (Pin 24) is 0.4V
ACOK (Pin 5) is 0.4V
ACDET (Pin 6) is 2.7V

Above in red are not good readings.

REGN should be ~6 volts.

Remove all power. Meter in resistance mode.

Check the resistance to ground of REGN pin # 24. What is the measurement?

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Above in red are not good readings.

REGN should be ~6 volts.

Remove all power. Meter in resistance mode.

Check the resistance to ground of REGN pin # 24. What is the measurement?

I don't know if it makes any difference, but the previous readings were done only with AC connected, this is due to the ASUS batteries somehow self-destructing by the smallest things, (I've had three of these boards kill the battery now).
With AC power removed, REGN is 10k.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

When checking the resistance or diode mode values, all power must be removed.

With no power, REGN is fine @ 10k and is not shorted.

Ok to remove the battery and use only the recommended power adapter.

The REGN pin is a very basic LDO and should provide a low current 6 volt output. As long as the Vcc is stable @ 19v, this charger IC should supply a steady 6 volts.

Suggest to seek out a fresh replacement of this component. They are very inexpensive on Aliexpress.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

When checking the resistance or diode mode values, all power must be removed.

With no power, REGN is fine @ 10k and is not shorted.

Ok to remove the battery and use only the recommended power adapter.

The REGN pin is a very basic LDO and should provide a low current 6 volt output. As long as the Vcc is stable @ 19v, this charger IC should supply a steady 6 volts.

Suggest to seek out a fresh replacement of this component. They are very inexpensive on Aliexpress.

Oh, I already have a bunch from last time I worked on a board like this. I'll get to replacing it ASAP. Thanks!

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Alright, changed the BQ IC,

REGN is now 6V

When first installed, I plugged in power, and the second mosfet showed 20V out, all good.

Installed the board, plugged in power, and it is now back to 4V, and still no sign of life (no lights etc.)
REGN is still 6V though.

ACDRV is still 0V.
ACOK is now 6V.
ACDET is still 2.7V.

[mon2]

Re: Dead ASUS ROG G14 (GA401)

You are getting closer

These are good readings except for ACDRV which should be ~25v.

As per the Bible written by @Piernov - see the above sticky, often the 2nd DCin mosfet raises the fault you are observing.

On your board, you should have a ~4k resistor between ACDRV pin and the GATE pins of the DCin mosfet. If you can locate this 4k resistor, remove it off the board. Do not lose the part.

Power up again. Confirm if the ACDRV pin is now ~25v.

Often the 2nd DCin mosfet will cause the ACDRV voltage to tank.

Before starting, do confirm that the main power rail is not with a low resistance value to ground. A low resistance on the main power rail (ie. after the 2 x DCin mosfets) means there is a shorted component.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

You are getting closer

These are good readings except for ACDRV which should be ~25v.

As per the Bible written by @Piernov - see the above sticky, often the 2nd DCin mosfet raises the fault you are observing.

On your board, you should have a ~4k resistor between ACDRV pin and the GATE pins of the DCin mosfet. If you can locate this 4k resistor, remove it off the board. Do not lose the part.

Power up again. Confirm if the ACDRV pin is now ~25v.

Often the 2nd DCin mosfet will cause the ACDRV voltage to tank.

Before starting, do confirm that the main power rail is not with a low resistance value to ground. A low resistance on the main power rail (ie. after the 2 x DCin mosfets) means there is a shorted component.

Yeah, had hoped it would work after the replacement, seeing 20V initially on the second DC-In mosfet

How would I go about finding the 4K resistor? There is quite the distance between the BQ chip and the second DC-In mosfet (many many resistors)
Also, ACDRV goes through a via in the board, so it makes it even more difficult to figure out.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

Is this the resistor you are talking about?

[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.

[jacobtc]

Re: Dead ASUS ROG G14 (GA401)

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

[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)

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)

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.