820-3437 Quarter fan spinning

[MOberdick]

Liquid damaged Air board with most corrosion being around SMC area. Ultrasonic cleaned that up very well. After cleaning had no light on the charger and no fans so I went ahead and proceeded to fix the onewire circuit which had both the 10k and 4.7k resistor blown. Light is back again but now with a quarter fan spin. U6100 area looks nearly spotless and I checked all the surrounding resistors. Pin 8 of U8160 also looks good and has voltage. Any tips on what to look for next? 3V3_S3 and 3V3_S0 are coming and going as the fan spins and turns back off but the S5 remains stable.

 

[aprendiz]

CPU VCORE missing or also pulsing??....

 

[MOberdick]

Pulsing as well.

 

[aprendiz]

Coorrosion around U1900 and /or U1950?

 

[MOberdick]

Not really, Very slight browning on just one of the test points near u1900 but it has continuity still

 

[Repairable]

Corrosion under SMC?

SMC_LID high?
SMC_ONOFF_L ?

 

[MOberdick]

SMC_LID pulsing 3.3v and then down.. ONOFF_L at a solid 3.4

 

[dukefawks]

Crap under SMC I think.

 

[MOberdick]

Reflowed. no change. Closing this one up. Thanks guys.

 

[dukefawks]

Uhm, pull SMC and reball, not giving up that easy....