Asus X512F No Power

[Ado02]

Hi,

I'm working on an Asus X512F laptop that wouldn't turn on initially. It did power up when I disconnected the keyboard, but it shut down soon after.

I think the problem might be around the keyboard connector area, where the battery connector and Charging IC (BQ24780s) are also located.

When the laptop doesn't charge or power on, the battery positive measures only 0.22v. When it does charge, it reads 6v. The ACDRV on the charging IC shows 3.15v, but it should be around 25v.

Any ideas on what else I should check, or if I'm on the right track?

[Techtiger]

Re: Asus X512F No Power

What supply do you get to the first two N-FETs (Source, Drain, Gate), and for the BQ24780 (ACN, ACP, CMSRC, ACOK, ACDET, REGN, VCC), supply?

[Ado02]

Re: Asus X512F No Power

ANC: 3.18v
ACP: 3.18v
CMSRC: 3.18v
ACOK: 6V
ACDET: 2.62v
REGN: 6v
VCC: 19.8v

[Techtiger]

Re: Asus X512F No Power

According to the measurements provided, two FETs are not switching. It seems that you haven't supplied the voltage readings for the first two N-FETs (Source, Drain, Gate). test them using a multimeter without power, in diode mode, on Source, Drain, and Gate. It's possible that one of the FETs or components connected to this line is faulty.

[mon2]

Re: Asus X512F No Power

With great care, flux and remove the ~4K resistor in series of the acdrv pin to the dcin mosfets. Do not lose this part. Then check if the acdrv pin outputs the ~25v without the 4K part. As noted a leaky dcin mosfet will cause this issue.

[mcplslg123]

Re: Asus X512F No Power

According to the measurements provided, two FETs are not switching. It seems that you haven't supplied the voltage readings for the first two N-FETs (Source, Drain, Gate). test them using a multimeter without power, in diode mode, on Source, Drain, and Gate. It's possible that one of the FETs or components connected to this line is faulty.

Better to check both fets in resistance mode(meter set to 200K or higher sclae).