820-2915 keep losing CPU_Vcore

[Ryanlen2]

Hi.820-2915, no liquid. Would power up then shut down almost instantly.
Found that cPU_Vcore was missing and U7400 wasnt putting out voltage to FETs. I replaced U7400 and all HS FETS. After this, computer booted into OS. Then I checked VCORE and found it was fluctuating between .75V and 1.1V. After this fans got high and computer shut down. Now back to square one, computer shuts down almost instantly. Fans spin no Vcore.

PPBUS and PPVIN_S5 are 12.56V.

PP5V_S0_CPUIMVP_VCC - 5V

6 Ohms on CPU_VCORE

Thanks. Have a good one.

Update -

Changed U7400, FETS and surrounding components again. Booted again for about 6 minutes with CPUVCORE at .75V then powered off. PPBUS was shorted to ground on Q7530. Replaced Q7530 PPBUS short is gone. Now its in a power loop with 1.1V on VCORE............ Now Dead CPU, I'm assuming?

 

[dukefawks]

I have had a few like this and they always were a headache. Need to replace all FETs U7400 and u7541. Still you can expect issues as I have not had much success with this.