macbook 820-3115 water damage, quarter fan spin

[Cocobill]

Hello,

I have an 820-3115 with water damage around U6100 and U3890 areas. Cleaned up and now getting a single quarter fan spin, no loop.

I started checking for shorts, but am not exactly sure what is meant by that: if I am to measure short to ground on PP3V42_G3H do I also have to measure all the sub-circuits in that list, like PP3V3_S5_LPCPLUS, PP3V3_S5_SMC, PP3V42_G3H_BATT, PP3V42_G3H_CHGR, PP3V42_G3H_ONEWIREPROT etc.? If not, I checked all the main rails and there is no short.

Any ideas?

 

[Cocobill]

Oh, and I do get a green light on the charger!

 

[dukefawks]

Could be anything. First check all traces to U6100 and try a known good chip/dump, save the old. CPU Vcore coming high during the fan pulse?

 

[Cocobill]

CPU Vcore is coming high for a moment. U6100 was replaced with one from donor board. Same issue. About checking rails for shorts: do I also need to test all the sub-rails or just the main ones?

 

[dukefawks]

Check everything, but as CPU Vcore is coming high that means all power should be ok. Chips from donor boards are many times not good as they are erased.