Asus x442u cant use adaptor

[Yosua]

Re: Asus x442u cant use adaptor

+3V LDO will be missing as perhaps 19V is not passing thru on this board. Since 3V PWM is not getting +19V as VIN ,it cant produce +3V LDO. So dont bother about SDA/SCL at this moment. You need to check why charging IC ACP/ACN is not 19V. Thats the 1st step for repairing this mb. Stay focussed on this issue alone till you fix it.

isn't it if acn and acp are lost because acdrv has not provided voltage to the gate on acfet, so that acfet can't be opened to supply 19v voltage?

[Adenitz]

Re: Asus x442u cant use adaptor

Yosua, your are right, it doesn't make sense to measure and expect any voltage on ACN and ACP pins when the MOSFTET is blocking the input voltage. This clearly can be seen in the attached file (extract from the datasheet).

[Yosua]

Re: Asus x442u cant use adaptor

Yosua, your are right, it doesn't make sense to measure and expect any voltage on ACN and ACP pins when the MOSFTET is blocking the input voltage. This clearly can be seen in the attached file (extract from the datasheet).

I've also tried to replace the bq24780s ic with another one but the result is still the same, and I'm surprised that the voltages on the vcc and acdet pins have met the requirements for the ic to produce the proper acdrv voltage.

correct me if i'm wrong or i missed something for this charger block measurement

[Adenitz]

Re: Asus x442u cant use adaptor

Few months ago, I have wasted a lot of time and almost ruined the motherboard, but the problem was with the charger. Sometimes it can also be an issue with the charging port itself because of which adapter is not properly recognized. I was stupid but lucky.

Master Sorin was also caught is something similar:
https://www.youtube.com/watch?v=AEzoQNNRhBI
https://www.youtube.com/watch?v=UIkVhi_MkQI

[Yosua]

Re: Asus x442u cant use adaptor

Few months ago, I have wasted a lot of time and almost ruined the motherboard, but the problem was with the charger. Sometimes it can also be an issue with the charging port itself because of which adapter is not properly recognized. I was stupid but lucky.

Master Sorin was also caught is something similar:
https://www.youtube.com/watch?v=AEzoQNNRhBI
https://www.youtube.com/watch?v=UIkVhi_MkQI

thanks for your advice sir, but I'm pretty sure that this is indeed a measurement that I'm missing, or indeed that my experience hasn't reached this point yet.

[usyusy]

Re: Asus x442u cant use adaptor

+3V LDO will be missing as perhaps 19V is not passing thru on this board. Since 3V PWM is not getting +19V as VIN ,it cant produce +3V LDO. So dont bother about SDA/SCL at this moment. You need to check why charging IC ACP/ACN is not 19V. Thats the 1st step for repairing this mb. Stay focussed on this issue alone till you fix it.

as advised by sir mcplslg123,

first of all just check Volt-in section (19v) i.e 1st, 2nd mosfets and CLR voltages and related caps etc.

[Adenitz]

Re: Asus x442u cant use adaptor

usyusy is right, you need first to check whether 19V is present after 1st and 2nd MOSFET.
1st and 2nd MOSFETS are (judging from the attached boardview) labeled:
PQ8901 and PQ8902

Resistors PR8936and PR8934 are both 4.02 kohm just like shown in "Typical application" section posted above. you batter charger IC is PU8901

PRS8901 is a current sensing resistor (10 mohm)
ADCDET should be little above 2.5V.

[Yosua]

Re: Asus x442u cant use adaptor

usyusy is right, you need first to check whether 19V is present after 1st and 2nd MOSFET.
1st and 2nd MOSFETS are (judging from the attached boardview) labeled:
PQ8901 and PQ8902

Resistors PR8936and PR8934 are both 4.02 kohm just like shown in "Typical application" section posted above. you batter charger IC is PU8901

PRS8901 is a current sensing resistor (10 mohm)
ADCDET should be little above 2.5V.

thank you sir, but previously I explained that 19v only appears on the first acfet on pins 5,6,7,8

and the acdet line on this bq24780s ic has appeared 2.65v

[mon2]

Re: Asus x442u cant use adaptor

From post # 2:

1) remove all power. Meter in resistance mode. Check the resistance across each front side mosfet.

Source and drain
Source and gate
Gate and drain

Look for low resistance values which means the mosfet is damaged.

Measure and post the above readings from the first 2 mosfets.

[Yosua]

Re: Asus x442u cant use adaptor

From post # 2:



Measure and post the above readings from the first 2 mosfets.

thanks sir for your little time, this measurement is using diode mode on a digital multimeter
fet 1
s-d = 471 ohms
d-g = does not appear
s-g = does not appear

fet2
s-d = 482 ohms
d-g = does not appear
s-g = does not appear

[mon2]

Re: Asus x442u cant use adaptor

What are the details of your power adapter ?

Voltage ? Current ?

Is it the official Asus power adapter ?

[Yosua]

Re: Asus x442u cant use adaptor

What are the details of your power adapter ?

Voltage ? Current ?

Is it the official Asus power adapter ?

yes sir i use the original adapter from asus and the output is 19v 1.75A

[mon2]

Re: Asus x442u cant use adaptor

See attached. Do you have a battery attached ? If yes, remove it.

Pin #15 is an active LOW signal. If LOW, then the charger IC believes the battery is attached and will DISABLE the first 2 mosfets from the adapter.

Try this, take the ACDET signal which is ~2v6 -> use a wire and attach it to the pin # 15 of the charger IC = BATPRES#.

Remove the battery and use only the AC adapter. Test again. Post your results.

Summary: We are attempting to change the logic level on BATPRES# line to make the charger IC turn on the first 2 mosfets.

This is getting messy...check the voltage on the RTC coin cell battery (CR2032). Replace it with a known good battery and test again.

The power sequencing charge in the posted (similar) Asus schematic notes that the RTC_BAT has to be the first power up rail.

[Yosua]

Re: Asus x442u cant use adaptor

See attached. Do you have a battery attached ? If yes, remove it.

Pin #15 is an active LOW signal. If LOW, then the charger IC believes the battery is attached and will DISABLE the first 2 mosfets from the adapter.

Try this, take the ACDET signal which is ~2v6 -> use a wire and attach it to the pin # 15 of the charger IC = BATPRES#.

Remove the battery and use only the AC adapter. Test again. Post your results.

Summary: We are attempting to change the logic level on BATPRES# line to make the charger IC turn on the first 2 mosfets.

This is getting messy...check the voltage on the RTC coin cell battery (CR2032). Replace it with a known good battery and test again.

The power sequencing charge in the posted (similar) Asus schematic notes that the RTC_BAT has to be the first power up rail.

I've connected it from PR9013(acdet) PIN 1 to PR8930(battpres#) PIN 2 but the voltage drops 0.98v sir

[mcplslg123]

Re: Asus x442u cant use adaptor

Yosua, your are right, it doesn't make sense to measure and expect any voltage on ACN and ACP pins when the MOSFTET is blocking the input voltage. This clearly can be seen in the attached file (extract from the datasheet).

The voltage on source(pin1-2-3) of 1st mosfet goes to CMSRC pin of charging ic. You should have +19V on ACN/ACP even when voltage is not crossing the 1st DC-IN mosfet. Gate voltage will be pulled high to 24V approx when ACDET is within range,ACN/ACP is 19V and CMSRC has 19V. So dont be foxed with gate voltage for now. Once again i repeat, you need to find out why ACN/ACP is not 19V. Thats the logical 1st step.

Its your choice to seek other's opinion and i respect that.

[Yosua]

Re: Asus x442u cant use adaptor

See attached. Do you have a battery attached ? If yes, remove it.

Pin #15 is an active LOW signal. If LOW, then the charger IC believes the battery is attached and will DISABLE the first 2 mosfets from the adapter.

Try this, take the ACDET signal which is ~2v6 -> use a wire and attach it to the pin # 15 of the charger IC = BATPRES#.

Remove the battery and use only the AC adapter. Test again. Post your results.

Summary: We are attempting to change the logic level on BATPRES# line to make the charger IC turn on the first 2 mosfets.

This is getting messy...check the voltage on the RTC coin cell battery (CR2032). Replace it with a known good battery and test again.

The power sequencing charge in the posted (similar) Asus schematic notes that the RTC_BAT has to be the first power up rail.

sorry but doesn't this mobo have the RTC battery together with the laptop battery?

and there is no cr2032 in this x442u boardview

[mcplslg123]

Re: Asus x442u cant use adaptor

@mon2 means main backup battery and not cmos cell.

[Yosua]

Re: Asus x442u cant use adaptor

The voltage on source(pin1-2-3) of 1st mosfet goes to CMSRC pin of charging ic. You should have +19V on ACN/ACP even when voltage is not crossing the 1st DC-IN mosfet. Gate voltage will be pulled high to 24V approx when ACDET is within range,ACN/ACP is 19V and CMSRC has 19V. So dont be foxed with gate voltage for now. Once again i repeat, you need to find out why ACN/ACP is not 19V. Thats the logical 1st step.

Its your choice to seek other's opinion and i respect that.

Sorry in advance, sir, I don't mean to ignore your advice, but I don't know at what point of measurement I should do to analyze the ACN and ACP voltages, please guide me, if I may know where did ACN and ACP start working, and What conditions must be met in order for them to work?

[Yosua]

Re: Asus x442u cant use adaptor

@mon2 means main backup battery and not cmos cell.

the voltage on the main battery is no longer left, sir and unfortunately I don't have a spare battery anymore, I'm sorry

[Adenitz]

Re: Asus x442u cant use adaptor

The voltage on source(pin1-2-3) of 1st mosfet goes to CMSRC pin of charging ic. You should have +19V on ACN/ACP even when voltage is not crossing the 1st DC-IN mosfet. Gate voltage will be pulled high to 24V approx when ACDET is within range,ACN/ACP is 19V and CMSRC has 19V. So dont be foxed with gate voltage for now. Once again i repeat, you need to find out why ACN/ACP is not 19V. Thats the logical 1st step.

Its your choice to seek other's opinion and i respect that.

I must say I don't follow. 1st MOSFET will let 19V from its drain to source only if there is a voltage about 24V on its gate (i.e. Vgs > 4.5V).

This is what is written in the IC bat charger documentation:
The ACDRV drives a pair of common-source (CMSRC) N-channel power MOSFETs (ACFET and RBFET)
between adapter and ACP. The ACFET separates adapter from system and battery, and provides a limited di/dt
when plugging in adapter by controlling the ACFET turn-on time. Meanwhile, it protects the adapter when the
system or battery is shorted.

Therefore, if there is no 24V voltage on the first gate, there will be no 19V on the source of 1StMOSFET = source of the second mosfet. IF ACFET is turned OFF there will be no 19V on the ACN and ACP .

I don't see how it is possible to have 19V from the adapter/charger when ACFET is blocked. I don't see the closed path. Please have a look at the attached file.