Asus Rog G551JM not charging and A5 VNE / A5 GND

[Kiop]

Hello

So i had a bad motherboard with a bad A5 VNE dosen't power UP without a battery so i change it but made a mistake and remove one of two good wich was good i know ...

So i changed it with a A5 GND but the battery dosen't charge so i thought may be it was the ic charger but coudnl't understand if it was the case or not i noticed there was big large track from the ic charger to the battery wich seems odd so i guess may be it really needs a A5 VNE .

I noticed on a good mobo for the Asus N551JM that on the A5 VNE on the gate i got 23,4 volts but not on the A5 GND just 19 volts .

So it was strange the two A5 VNE are the first step of the power supply .

I checked also and A5 VNE and A5 GND should be compatible and intercheangable .

Finally i took 2 mosfet from a Asus X555LD and it works fine now laptop are charging the battery .

But why the A5 VNE and the A5 GND are different ?

Any idea ?

[Kiop]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

[mcplslg123]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Both are N channel 30V,48A mosfets-so are same and replaceable. Earler fets or one of them might be defective.

[Kiop]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Yes it should but no , i tried with 4 of them i ended taking a A5 VNE from a working mobo and changed the first one i mean the top one by that A5 VNE and now everything is working fine and all the tensions are there battery charging , mobo working fine ...

And i don't understand why i got 23,4 volts on the gate of that mosfet , where is coming from , from the mosfet or the mobo ?

[mcplslg123]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Getting 23v at pin4(Gate) is normal as its a N channel mosfet. For any N channel mosfet , gate voltage is 19V+6v approx. For P channel , The gate voltage is lower then 19v(Usually 6-12V). So its fine. The gate is controlled by your charging IC.

[ktmmotocross]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

gate is driven by buck circuit that boost base to 24V

[P1nkSl1p]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Hi I have the same issue with a gl551jw and really want to know what the code on the mosfet you used is. I tested it and I get no voltage out of it. Just want to know what the code is to see if I can buy new ones. Also are the both chips the same? Because the bad one has no codes on it and I wasn't sure if they were.

[Manuelh]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Is this thread. Still active ?
I am looking for the board schematics for this laptop .
Running into the same charging issue

[SMDFlea]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Is this thread. Still active ?
I am looking for the board schematics for this laptop .
Running into the same charging issue

Schematic requests go here -> https://www.badcaps.net/forum/forumdisplay.php?f=41

Use the forum search, it might be posted already.If not,start a new thread in the schematic requests section .

[Manuelh]

Re: Asus Rog G551JM not charging and A5 VNE / A5 GND

Requested the schematic
Strange how we are all experiencing the same issue with this mainboard