Determining dead CPU, Help with Voltage Injection

[silver60618]

Hi Gang, I am trying to repair an Asus laptop motherboard with my basic knowledge. Laptop will not power on. I detected a short on the drain of 2nd Mosfet DC charging circuit and the current sense resistor.

I followed the power rail to the CPU/GPU. All inductors and nearby capacitors showing .02-.09 resistance/short.

I applied 2v, 3a to the current sense resistor and the only hotspot on thermal cam was the CPU .

Does this mean the CPU is dead? or am I missing a troubleshooting step?


any help would be appreciated!!

[mcplslg123]

Re: Determining dead CPU, Help with Voltage Injection

A 2 ohms resistance on cpu core rails is what you expected on 10th/11th gen cpu's. Its wrong to inject 2V-anything more then 1V may kill the cpu if there is a shorted high side mosfet on vcore rail.

You should de-solder the current sensing resistor and inject 1V/5A on the shorted pad of this resistor and wait for 10-15 mins to feel anything hot. With these newer board,nothing will become red hot and you just need to feel which area of the board is getting slightly warm and then narrow down on your search for faulty part. A thermal camera helps in such a situation along with a dc supply of 10A. However, i'm afraid you may have killed the cpu by injecting 2V.Lets keep our fingers crossed.