820-3437 Has S0 state but no CPU

bjf

Member
The CPU area was hit by liquid on this board. Not terrible though. I've gone through it and checked everything and replaced U7200. No CPU voltage. It's at .040V. No short on vcore. U7200 has HS_COMPUTING and 5V_S0 coming in. 3V3_S0 is also present on the board. Not sure what I should be looking for next to get CPU power.
 

bjf

Member
Diode on CPU_VR_EN is pretty normal at .270. The only damage that I can see is right in the U7200 area. PPVRTC_G3H is present. The board is seemingly in a perfect S0 state, with all the normal voltages minus vcore.
 

larossmann

Administrator
Staff member
The CPU requests vcore from the U7200 prior to U7200 sending vcore via CPU_VIDSOUT. If the CPU area were ht with corrosion there are two likelihoods.

1) CPU has corrosion under it.
2) CPU is dead.

I would give it an ultrasonic at something very high like 80-85 celsius for a short time period like 30 seconds to get rid of any hard gunk that may be remaining. I would also check R7280 and R7279, the pullups on the data lines where U7200 is told what to create for the CPU.

After that, I would toss in the towel. This is obviously assuming pins 16/17 of U7200 are receiving the voltage they are supposed to.
 

dukefawks

Administrator
CPU_VCCST_PWRGD present? Corrosion around U7200 is always a bitch as the CPU may already be dead. Vcore not shorted?
 
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