Asus x442u cant use adaptor

[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?

[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 ?

[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.

[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

[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

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?

[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

?? 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 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 ?

[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.

[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

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.

[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.

[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

[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