HP Victus 15-fb dag3pamb8d0 Short on VCORE – How to Confirm CPU Fault?

[adelfr2009]

I have a laptop HP Victus 15-fb with motherboard DAG3PRMB8D0, CPU Ryzen 7535HS, and GPU RTX 2050. The laptop has a power issue: it does not turn on at all, and there is no light on the DC jack.
After inspection, I found that an NMOS near the charger input had a short. I replaced it, but the short remained on the 19V line. I checked the charging circuit and it was fine, but the short appears after the current sense resistor near the charger. The charger does not pass current when connected, so I inject 3V–4V after the sense resistor. No component gets hot, except the CPU which becomes slightly warm.

The 3V and 5V rails are working fine, but the short is present in the CPU and GPU area. I removed one coil connecting the VCORE line to the CPU, and when measuring the resistance on the load side, the multimeter gives a beep (short). I injected 1V / 1A into the output, but the CPU did not heat up.

When measuring, I found that the drawn current is about 0.185A, and the voltage on the capacitors at the load side is about 0.57V.

Diode mode measurements:

3V coil → 0.438

Large coil (GPU supply) → 0.051

Another voltage coil → 0.415

Coil near RAM → 0.414

CPU coils → 0.006

GPU coils → 0.003

Coil near charging IC → 0.461


I suspect the CPU is faulty. How can I confirm this? Do I need to remove all coils on the VCORE line to be sure, or is removing one coil enough?

[DeXXter]

What resistance do u have on B+/19v power rail? 1ohm, 2ohm? from the main current sensor you can measure resistance to gpu and cpu coils to check if you have a short there or a shorted mosfet, also you can inject 1v on that same main current sensor and measure voltage on all the coils because you might have a current leak if that's the case you have to identify which phase, so then you start lifting/desoldering coils/inductors, ofc I guess you checked you didn't have some kind of hole or a burnt spot on the motherboard.

[adelfr2009]

I injected 1V after the first current sense resistor and discovered there was leakage towards the CPU side, because when I measured the voltage at the CPU coil I found 0.5V. I then removed the coils and found there was a short on the side of one of the MOSFETs. The MOSFET is a dual MOSFET, and the short was on the high side — this was the cause of the leakage.
Now I need to know whether the CPU (Ryzen 7535HS) survived or not. When I measured the resistance on the CPU side, I got 2.6Ω (with bip). Next, I have to figure out the root cause of the short that led to all of this.

What do you think?

[ERRA]

I injected 1V after the first current sense resistor and discovered there was leakage towards the CPU side, because when I measured the voltage at the CPU coil I found 0.5V. I then removed the coils and found there was a short on the side of one of the MOSFETs. The MOSFET is a dual MOSFET, and the short was on the high side — this was the cause of the leakage.
Now I need to know whether the CPU (Ryzen 7535HS) survived or not. When I measured the resistance on the CPU side, I got 2.6Ω (with bip). Next, I have to figure out the root cause of the short that led to all of this.

What do you think?

Repalce the faulty mosfet and do the injection test again (no more than 0.9v) !!