ASUS ViviBook X512F no power

[mcplslg123]

Re: ASUS ViviBook X512F no power

Replace the 2nd mosfet, dont replace the charging IC now. Power up, what is the status?? CLR stands for Current Sensing Resistor usually located just after the 2nd dc-in mosfet.

[sect-sin]

Re: ASUS ViviBook X512F no power

Replace the 2nd mosfet, dont replace the charging IC now. Power up, what is the status?? CLR stands for Current Sensing Resistor usually located just after the 2nd dc-in mosfet.

mcplslg123,

Thanks for the additional info. Tonight I will search for the current sense resistor as well, just to be on the safe side, and in order to learn more. Am I right in assuming that it should have a low value to begin with? Would it connect the Gate with the Source, or something else?

Cheers,

sect-sin

[mon2]

Re: ASUS ViviBook X512F no power

https://youtu.be/vgeVpYWkwBM

[Simplebeans]

Re: ASUS ViviBook X512F no power

Simplebeans,

I got the 2.1 revision of the board, the area looks exactly the same like on the 2.2 version. I measured the component out of circuit, it is definietly a 0 ohm resistor.

I have the exact same problem with my board, and wish us both good luck to fix it.

Cheers,

sect-sin

Hi thanks and appreciate your help on the 0Ω resistor, at least we know what that part is now.

Do you have any schematics for this board at all?

[sect-sin]

Re: ASUS ViviBook X512F no power

Hi thanks and appreciate your help on the 0Ω resistor, at least we know what that part is now.

Do you have any schematics for this board at all?

None at all. For the majority of stuff I repair or try to repair, there seems to be no documentation at all.

[Simplebeans]

Re: ASUS ViviBook X512F no power

None at all. For the majority of stuff I repair or try to repair, there seems to be no documentation at all.

Haha thats why its nice working on Macbooks, there is always a schematic(s).

[Simplebeans]

Re: ASUS ViviBook X512F no power

OK. Lets make simple checks to begin with.

01.Measure voltage on Pin1-4-8 of dc-in mosfets.
02.Measure resistance on CLR.
03.Measure charging IC pins for ACN/ACP/CMSRC/ACOK/ACDET/REGN/VCC

01) The first mosfet in the dc-in circuit at the drain, source all measure 19V and the gate measures 24V. The power reaches the second mosfet, there at the drain then measures at 19V however no voltages measure on the source/gate side of second mosfet.

02) The main current sense resistor i can see, is placed near the first mosfet in the dc-in circuit, the resistance at this resistor (meter is resistance mode 20MΩ), black probe to ground point and red probe to PIN #1/2 @ the resistor measures 3.2MΩ and rising.

03) The voltage measurements at the charging IC (TI BQ24780S chip):
ACN= 19.43V
ACP= 19.42V
CMSRC= 18.96V
ACOK= 5.95V
ACDET= 2.64V
REGN= 6.00V
VCC= 19.21V

[mcplslg123]

Re: ASUS ViviBook X512F no power

The charging IC measurement seems fine. There should be voltage on the source of 2nd fet as you are aware. Confirm it by measuring on CLR?? There should not be any voltage here in your case. Is the battery discharge fet not shorted??

[Simplebeans]

Re: ASUS ViviBook X512F no power

The charging IC measurement seems fine. There should be voltage on the source of 2nd fet as you are aware. Confirm it by measuring on CLR?? There should not be any voltage here in your case. Is the battery discharge fet not shorted??

Yes i just measured and the current sense resistor which does have a measurement of 19V on both sides of it, PIN's #1 and #2 respectively.

I have just noticed something interesting that i may not have noticed previously. So the first dc in mosfet (M3056M) when measuring resistance from S-G: i get 97KΩ however the second mosfet (M3054M) S-G measures 2.6KΩ. The interesting thing is all the other mosfets in the circuit after these mosfets, that i have mesured so far are showing all at around a 7.3KΩ measurement at the S-G. This is the only anomoly however that i am noticing at present.

[mcplslg123]

Re: ASUS ViviBook X512F no power

You should replace the 2nd mosfet first before troubleshooting further. Probing further without replacing it may be futile and pure waste of time.

[Simplebeans]

Re: ASUS ViviBook X512F no power

You should replace the 2nd mosfet first before troubleshooting further. Probing further without replacing it may be futile and pure waste of time.

Ok 2nd mosfet issue now resolved, resistance readings are good now. Still no power.

[Sephir0th]

Re: ASUS ViviBook X512F no power

New overview necessary since you have 19V at the main power rail now.
Any coil which have voltage? 3.3V at the power button by any chance?

[Simplebeans]

Re: ASUS ViviBook X512F no power

New overview necessary since you have 19V at the main power rail now.
Any coil which have voltage? 3.3V at the power button by any chance?

I appreciate your input but really not sure what you mean? The status of the machine has not changed (apart from replacing a mosfet), the voltage measurements are all the same as when i started this thread. The only inductor that has a voltage reading is the one right near the charger IC. All the other inductors are showing 0V.

[sect-sin]

Re: ASUS ViviBook X512F no power

Hello everybody,

Today finally the replacement MOSFETs arrived from China. I started with replacing QM0930M since it had the dead short, and voilá, the notebook runs again! One more machine saved from e-waste, I am so happy!

I thank you very much for your help and support, I really appreciate you guys.

Cheers,

sect-sin