Asus G513 dead

[reformatt]

Just need a sanity check on this one. I have an Asus G513 ROG lappie here dead as a door knocker. No volts getting past the first FET. Has a BQ24780S charger IC at least, but no schematics or board view.

So ACDET is low at 1.7V, REGEN is also low at 5.4V. On the ACDET pin, there's a few resistors etc and also a SOT323 package marked A7t. Now in my searches this is a BAV99W dual diode. But the datasheet doesn't actually confirm this marking either. I haven't found this diode on any other board either just to compare to. It definitely doesn't meter right, I drew this out, and it seems to be some kind of clamp on the ACDET pin.

As I don't have schematics, not sure. I don't have any other dual diode package in this config on any other board. Can anyone confirm that A7t is a BAV99W? I've desoldered and moved it over on this picture to check it, definitely reads bad.

Motherboard number is G513-6050A3249301-MB-A03

[reformatt]

Re: Asus G513 dead

With that out of circuit, my ACDET is spot on 2.6V, REGEN is 6V. Haven't gone any further than that, Guess I'll just order it.

[mon2]

Re: Asus G513 dead

Hi. what is the voltage to ground of ACDRV?

If not ~25v, remove the series resistor on this pin. Then test again for the same.

[mcplslg123]

Re: Asus G513 dead

BAV99W in SOT323 package. Sure about it

[reformatt]

Re: Asus G513 dead

Many thanks. ACDET was fine after removing it, but still no ACOK. Realised pretty quick there was a short on the +19V rail. Was a shorted cap under the heatsink near the CPU (that Seek camera has paid for itself many times over).

I don't have that diode but it works currently without it. Pretty sure it's some protection device although I'm not clear what the reasoning is.

[mon2]

Re: Asus G513 dead

ACOK is an open drain output.

Some designers use REGN as the pull-up voltage for this signal pin.

Others use an ALW for the pull-up voltage. The ALW rail will only function after the 2nd dcin mosfet is enabled.

The DCin mosfets will only enable if ACDRV is ~25v.

If ACDRV is not ~25v, then remove the 4k resistor on ACDRV pin and measure for this rail again.

Summary, as per the above sticky on charger circuits, often the 2nd DCin mosfet fails and needs to be replaced.

It will be a N-channel mosfet since the BQ charger IC is onboard.

Do confirm if there is a local pull-up on the ACOK pin.

[piernov]

Re: Asus G513 dead

I don't know about this Asus but some Acer laptops have a DC-in jack detection feature with a latch in the DC-in jack that pulls ACDET low when it's not plugged all the way in.

[reformatt]

Re: Asus G513 dead

After I got rid of the short on +19v, ACOK went to 6V (REGEN).

I was mindful of that Acer feature of disabling ACDET but the dc jack didn’t have the extra terminal for it.

Be so much easier just to have schematics like we used to years ago. One reason I don’t recommend asus lappies as info needed for repair is rarely, if ever, available.

[mon2]

Re: Asus G513 dead

After I got rid of the short on +19v

How?

[reformatt]

Re: Asus G513 dead

Was a cap on the edge of the board. Heatsink needed to be removed to get at it. Can't tell you a component designator, closest point of reference from the silkscreen was PAD60610. As it was a just a decoupling cap for a buck converter input and no schematic etc, a 10uf would probably be sufficient, but put in a 22uf 0805 to be sure.

[Luís Amaral]

Hello, i have similar problem on this motherboard. ACDRV is 2-3V, if a make a bypass on fist mosfet motherboard woks fine, charger and mosfets replaced, REGN OK, ACDET OK,... anyone can explain what can i do more on this cases ???