Asus FA506IV - AL116 no 5V and below

[aico60]

Hello Guys,

When I first bought the laptop, I knew that it was been worked on.
When I received it, I saw that there were mosfets missing, however there were 3.3V on the Power button, as well as 5V in the USBs (I have tested with USB lamp). I tried to power it on just to see if the fans would spin. They did not.
The audio chip was heating up, so I removed it (there were still 5V and 3.3V available)
Once I received the Mosfets, audio chips, IC, etc., the 5V rail disappeared, as well as 3.3V and 1.2V. The main rail (19.5V rail is OK).
Haven't measured others except those.
I tried replacing the IC in case it went faulty, but it was still the same so I removed it completely.

Now the laptop has shorted 3V and 1.2V. 5V is not shorted but it is missing.
I have measured some caps which are filtering caps right below the RAM when the board is flipped (pin 1 is 1.2V and pin 2 is GND) and they are short.
I think that the 1.2V is the issue here.

I have tried injecting 1.2V at max 1.5A and nothing is heating up (checked with thermal cam).

MB model is DABKXBMBAD0 REV D

I will attach pics of the MB, schematics and a PDF boardview.

Caps I measured are marked with Red on the pics.
I have also measured pins 5-8 on one of the missing mosfets (near battery connector) which should measure at 1.2V but it is shorted. I have marked it on the second pic.
The mosfet is PQ17 on the schematics and BV.
Pin 5-8 is connected to PU7 pin 16 and everything connected to them is shorted, however I doubt that PU7 is bad.

Any advice on how to proceed will be appreciated!
Sorry if my explanation is not clear.

Thank you!

[reformatt]

Re: Asus FA506IV - AL116 no 5V and below

Took a quick look at this. So you've attempted to run this board with the low side MOSFET missing for the 1.2V_SUS buck converter? Not a good idea if so. Over voltage or bad regulation on low voltage rails normally doesn't end well. This directly feeds the APU.

Simultaneous shorts on 2 rails like 3.3V and 1.2V is pointing to your APU I'm thinking.

[aico60]

Re: Asus FA506IV - AL116 no 5V and below

The 3.3V must have not been shorted at the moment of testing since the EC did have power.
Based on my measurings, only 1.8V_SUS and 1.2V are shorted.
But when I inject voltage, nothing is getting hot, not even warm. I have tried 0.7V and went up to 1.8A.
Seems really odd to me.

[Sephir0th]

Re: Asus FA506IV - AL116 no 5V and below

Nothing odd here. It just additionally points to a dead APU, besides the other serious mess which was done, as already summarized before.

Can't you raise the Amps? 1.8Amps might be not enough

[reformatt]

Re: Asus FA506IV - AL116 no 5V and below

Whatever rework you did potentially introduced the fault. I've had boards which turned out to be complete clusterfucks for no reason at all because of some overvoltage on a low voltage rail, and my rework resulted in a dead PCH/CPU/APU. Some boards you can fix, some you can't.

Try a thermal camera on the APU, or use IPA during voltage injection.

[mcplslg123]

Re: Asus FA506IV - AL116 no 5V and below

APU is shorted for sure. Dont waste your time on this mb.

[aico60]

Re: Asus FA506IV - AL116 no 5V and below

If the APU was shorted, wouldn't it get hot?

I have tried raising the voltage to 1V and the amps to 3A and still can't see any warm components on the thermal cam.

[Xibit1990]

Re: Asus FA506IV - AL116 no 5V and below

Is your problem fixed? What was the cause?

[guyandpit]

Re: Asus FA506IV - AL116 no 5V and below

hi any update on this? thank you