Asus Vivobook s510u - not charging

[samstown]

Hello,

I got this Asus Vivobook with 10% battery left, so it was working on battery (now battery is empty). When pluging power supply it was not charging. Power supply is working, I get 19.4V. When connected I can measure 19V until MOSFET.

I tought replacing MOSFET would do the trick... but it doesn't. Exact same behavior with a new MOSFET, not same model.. maybe that's why ?

The original MOSFET (on the pictures) is M3056M and I replaced with AON6414A.

Thanks for your help.

[mon2]

Re: Asus Vivobook s510u - not charging

Hi. Will trade services for some of your chocolate

Near these mosfets, locate the charger IC - what are the topside markings? Most likely will be the 'BQ' series from Texas Instruments. Post the full markings and if possible a clear close picture of the area for a review.

[samstown]

Re: Asus Vivobook s510u - not charging

Thank you for your help, I am lucky that you always reply to my post.

I have some friends in Canada, next time I see them, I'll gave them some chocolate, so they can post it from Canada to your place

Near the mosfet, I see
M0930M
D82046

[mon2]

Re: Asus Vivobook s510u - not charging

Hi

While the original mosfet is able to handle higher peak currents, the replacement is fine to use as a replacement.

Review the logic board for a square ic that should be near the dcin connector area. Topside markings should be 'BQ' or similar. The same charger IC will drive these mosfets linked to the battery charging circuit. That is, the gate pin #4 of the mosfet will feature a series resistor and the other side of the series resistor will be to the charger IC.

We need to know the charger IC markings or a schematic of this board. Being Asus, doubt the schematic is available. Will check my database of schematics once at the office.

[piernov]

Re: Asus Vivobook s510u - not charging

https://www.badcaps.net/forum/showthread.php?t=90356

[mon2]

Re: Asus Vivobook s510u - not charging

See attached.

From:
https://www.badcaps.net/forum/showthread.php?t=70050

your logic board is or should be close to this one:

Mainboard is ASUS X510UNR REV 3

Can you confirm ?

[koby058]

Re: Asus Vivobook s510u - not charging

mon2 you made me lough with the chocolate it reminded me the jaffa oranges.

you are great

[samstown]

Re: Asus Vivobook s510u - not charging

Thank you.

ok, I located BK chip near battery connector.
BK24780S

I can measure various volatage to that BK chip. I've check caps and fuse, can't find culprit.

unfortunately, I need to go for now... I won't be online until tomorrow.

[mon2]

Re: Asus Vivobook s510u - not charging

Review the voltage to ground of

REGN pin
ACDRV pin

If ACDRV is not ~25v then remove the 4k series resistor and test again if the ACDRV is at the required ~25v.

[samstown]

Re: Asus Vivobook s510u - not charging

Thanks.

I don't get 25V on acdrv . ok I am looking for resistor 4K PR8918 probably on the other side.


REGN pin 24 = 6.0V
ACDRV pin 4 = not stable, 0, then peak for 1, then 0 then peak to 15... o

[mon2]

Re: Asus Vivobook s510u - not charging

Remove the 4k resistor on ACDRV. This is to disconnect the load which are the gate pins of the 2*dcin mosfets.

Test again the ACDRV voltage with the 4k removed.

It is not that the 4k resistor will be defective but that the mosfets are. They are pulling down the ACDRV voltage.

Post the ACDRV voltage without the 4k resistor.

[samstown]

Re: Asus Vivobook s510u - not charging

I think I found the problem. Pin 3 and 4 were touching each other. I've clean it and now it's charging !! I'll duoble check and let you know. Thank you

[samstown]

Re: Asus Vivobook s510u - not charging

Hmmm.... almost there...Laptop is booting but battery doesn't charge.... Works fine with power supply but shutdown after 10 seconds if I unplug. The battery was ok when I got it so there must be something missing. I will open it again tomorrow to make sure all cables are plugged correctly.

[mon2]

Re: Asus Vivobook s510u - not charging

Check ACOK, ACDRV pins on the charger IC (voltage to ground).

The battery pack will have SMBUS pins (aka I2C) with SCL & SDA interconnect.

Measure the voltage to ground of each pin on the battery connector. If the charger IC is unable to communicate with the BMS (battery management system) inside the battery pack, the charging will not proceed.

[samstown]

Re: Asus Vivobook s510u - not charging

With your help, problem identifed. Mosfet M1830 was short. When I removed it, PC boot but doesn't charge. I've tried to repalce it with what I have AON7410 or AON7702A, it boots but after 2 min PC goes into standby and doesn't boot anymore... i need to remove mosfet and then it boots again.

I've looked at datasheet for M1830 but can't find good data.
I have also the following that I could use.

AO7408 QFN-8 MOSFET
AON6414AQFN-8 MOSFET
FDMC8884 8884 QFN-8 Chipset

What would work the best ?

[mon2]

Re: Asus Vivobook s510u - not charging

Review the path of the gate pin #4 of this mosfet. Where does the series resistor connect to on the charger IC?

How do you know if this part is defective? Low resistance reading

[samstown]

Re: Asus Vivobook s510u - not charging

Review the path of the gate pin #4 of this mosfet. Where does the series resistor connect to on the charger IC?

How do you know if this part is defective? Low resistance reading

Thermal camera show that ic flashing. When I remove it, it works.
If I measure it, all pins are short from one site to the other.

[samstown]

Re: Asus Vivobook s510u - not charging

Review the path of the gate pin #4 of this mosfet. Where does the series resistor connect to on the charger IC?

How do you know if this part is defective? Low resistance reading

From PIN4 (Gate) it goes to pin2 (ACP) of charging IC trough a filter, pics attached.

Do you think the problem is not the mosfet but something else ?

[mon2]

Re: Asus Vivobook s510u - not charging

Please review carefully and check figure 17 of the attachment datasheet. ACP pin should not be connected to the mosfet gate pin.

[samstown]

Re: Asus Vivobook s510u - not charging

Sorry, I am unable to find where pin 4 (Gate) is going. I can find it on side B but there's no componenent on that "line" and after this i don't know where it goes.

When I remove mosfet it works but doesn't charge. If I place a new mosfet, it gets hot and die after 10 seconds, PIN4 is probably shorted but I can't find where.