[SOLVED]820-3023 no CPU Vcore

[ytesfay80]

This board was said to have liquid damage but I can't find much of any except for a little on the I/O Board. There are discolored probe points in places but I don't see any corrosion anywhere.

Anyways, the fans turn on when the charger is plugged in but nothing appears on the screen and there is no vcore. I do feel the U1800 chip get slightly warm so I think the PCH is working.
PPBUS_G3H, PPVRTC_G3H, 5V_S0, 3v3_s0 and ALLSYS_PWRGD were all present.

PPVCORE_S0_CPU and PPVCORE_S0_AXG show 0v but PP1V5_S3_CPU_VCCDQ, PP1V05_S0_CPU_VCCPQE, and PP1V8_S0_CPU_VCCPLL_R all had the correct voltage on them.

I'm not sure exactly where to start in troubleshooting vcore on this model.

 

[ytesfay80]

Update: I went to the U7400 Chip to troubleshoot and I noticed the IMVP_TON resistor was corroded on one side so I replaced it and now this machine is working perfectly fine and vcore is back.

This can be marked solved.

 

[dukefawks]

Check U7400 area, pin 1 should of course have 3V and R7401/2 are suspect.

 

[ytesfay80]

dukefawks Yes. I posted an update message at the same time you posted your message. R7402 turned out to be the issue so this can be marked solved.