Asus x442u cant use adaptor

[Yosua]

Re: Asus x442u cant use adaptor

Check to see if you have a load switch at PU8802.

You are missing +3VA_EC. Yet, you have +3VA.

The load switch passes through +3VA to create +3VA_EC. Check the schematic posted earlier to compare against your logic board. If found, measure the voltage of the enable pin of this load switch. Post your updates.

after I changed the load switch then 3va ec appeared only 0.07v sir

[Yosua]

Re: Asus x442u cant use adaptor

Check to see if you have a load switch at PU8802.

You are missing +3VA_EC. Yet, you have +3VA.

The load switch passes through +3VA to create +3VA_EC. Check the schematic posted earlier to compare against your logic board. If found, measure the voltage of the enable pin of this load switch. Post your updates.

thanks sir, but do you mean the load switch is PU8001 on boardview?

IC which has 14 pin

[mon2]

Re: Asus x442u cant use adaptor

Check to see if you have a load switch at PU8802.

You are missing +3VA_EC. Yet, you have +3VA.

The load switch passes through +3VA to create +3VA_EC. Check the schematic posted earlier to compare against your logic board. If found, measure the voltage of the enable pin of this load switch. Post your updates.

[Adenitz]

Re: Asus x442u cant use adaptor

there is indeed a Regn that can penetrate anc

Thos is quite possible, since REGN is about 6V and is generated internally inside the chip. If possible, remove the chip and measure resistance between REGN and ACN/ACP pins on the motherboard. Maybe this is shorted not inside the chip, but on the mobo itself.

[Yosua]

Re: Asus x442u cant use adaptor

Do you feel comfortable with the replaced charger IC ? Consider to flux it and hot air till it swims into place with tweezers. Just to rule out any possible shorts underneath the QFN package pins.

Also observing that the replacement is from TI vs. the original used by Asus. According to the internet, the 2 devices are cross compatible. Is this 100% confirmed ?

Yes, I'm sure sir, I've replaced with 3 ICs, but still the same one of the ICs is indeed damaged, but the other 2 ICs are still good, and work on other Mobos, after I searched, there is indeed a Regn that can penetrate anc

please open this picture from the first order shows the path of screenshot 4 until screenshot 8

[Adenitz]

Re: Asus x442u cant use adaptor

If there is no battery connected and if the adapter is connected, then this 5V can come only from the input 19V via IC chip. There is no other explanation.

[mon2]

Re: Asus x442u cant use adaptor

Do you feel comfortable with the replaced charger IC ? Consider to flux it and hot air till it swims into place with tweezers. Just to rule out any possible shorts underneath the QFN package pins.

Also observing that the replacement is from TI vs. the original used by Asus. According to the internet, the 2 devices are cross compatible. Is this 100% confirmed ?

[Yosua]

Re: Asus x442u cant use adaptor

?? Can you explain ?

This is from your earlier posts. This power source is from the AC adapter.

How does this voltage reach the ACN / ACP pins if the mosfets are expected to be off?

so it's like this, when the adapter is connected, pin number 5678 acfet has 19v, and pin 1234 is 0v

then on pin 1234 rbfet 0v too, but on pin 5678 there is 5v

I also wonder why it can be like this, maybe there is a problem in the battery line, or is there a problem with the regn which is leaking and draining 5v?

[mon2]

Re: Asus x442u cant use adaptor

do you think this has something to do with this 5v shuffle voltage?

?? Can you explain ?

This is from your earlier posts. This power source is from the AC adapter.

How does this voltage reach the ACN / ACP pins if the mosfets are expected to be off?

[Yosua]

Re: Asus x442u cant use adaptor

Source drain resistance of 470ohms on a Mosfet does not sound right to me. I would expect kohms.

do you think this has something to do with this 5v shuffle voltage?

[Yosua]

Re: Asus x442u cant use adaptor

Source drain resistance of 470ohms on a Mosfet does not sound right to me. I would expect kohms.

acfet = 462 k ohm
rbfet = 491 k ohm

[Yosua]

Re: Asus x442u cant use adaptor

It is strange that you have some voltage on ACN / ACP pins yet the first 2 mosfets are not enabled.


leaky mosfets ?

Have you considered to replace both mosfets ?

Fet's condition is still good, I've also replaced it

[Adenitz]

Re: Asus x442u cant use adaptor

Source drain resistance of 470ohms on a Mosfet does not sound right to me. I would expect kohms.

[mon2]

Re: Asus x442u cant use adaptor

It is strange that you have some voltage on ACN / ACP pins yet the first 2 mosfets are not enabled.

1.acn = 5.61v
2.acp = 5.61v

leaky mosfets ?

Have you considered to replace both mosfets ?

[Yosua]

Re: Asus x442u cant use adaptor

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.

on the acn and acp pins there is a 5.45v voltage, does this mean there is a problem?

[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.

[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

[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?

[mcplslg123]

Re: Asus x442u cant use adaptor

@mon2 means main backup battery and not cmos cell.

[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