820-3662 Liquid damage no S4

[thetech]

Hi everyone, I'm stumped here.

Liquid damage around U7330 and battery connector. Replaced corroded capacitors around U7330, got the board to power on then will not enter S4. Then noticed area between Q7155 and battery connector very hot. PPVBAT_G3H_CONN shorted to ground. Removed Q7155, no change.

Rails are
PPBUS_G3H 12.55V
PP3V42_G3H 3.42V
PPVIN_S5_HS_COMPUTING_ISNS 12.55v
PPVIN_S5_HS_OTHER3V3_ISNS 12.56v
PPVIN_S5_HS_OTHER5V_ISNS 12.55
PP3V3_SUS 3.34V
PP3V3_S5 3.34V
PP3V3_S3 0!
PP3V3_S0 0
PP5V_S5 5.04V
PP5V_S4 0
PP5V_S3 0
PP5V_S0 0
PP3V3_S4 0.45v
PP3V3_SUS 3.34
PPVRTC_G3H 3.34
PM_SLP_S4_L 0v

Thanks

 

[dukefawks]

Not what you want to hear but corrosion around U7330 will usually kill the CPU.

 

[thetech]

I was hoping since I had it working initially after repairing the damage that the CPU might be ok. Is the only way to check for bad CPU removing U7330 U7320 and U7310 and see if it turns on or do I just assume the CPU is shot?

 

[dukefawks]

You didn't mention it worked. The short on PPVBAT_G3H_CONN must be inside the board too. Is there a short on CPU Vcore?

 

[thetech]

I should have worded this better "got the board to power on then will not enter S4". Anyhow CPU VCORE (PPV_S0_CPU) resistance to ground is 29.3 ohms.

 

[dukefawks]

I wouldn't put too much effort into this thing as the CPU may very well be dead. Corrosion around any Vcore regulators are usually deadly. If this is really the only corrosion on the board expect the CPU to be gone.