820-3437-B no power, no green light

WeLoveApple

New member
Changed ISL6259 from donor board. Green light returned. Fans spinned up for 2-3 seconds.
Then after some attempts green light went away.
PPBUS_G3H is present this time.
Those resistors seem okay.
 

WeLoveApple

New member
Tested with 3 IO cables. Same.
Also I re-checked those resistors. R7005 was too high 300ohm instead of 20. Not sure why I missed that before. I changed it, now it is 20ohm as it should but nothing changed.
There is something weird that might be relevant information: when i plug the charger in another laptop and put it back the charger light returns. It remains even after a few attempts of connecting and disconnecting from IO board. It start the fan for 2-3 seconds then it stops.

I fixed that retina board 2 days ago that was behaving somewhat similar by reballing the SMC. Does it worth a try in this case??
 

dukefawks

Administrator
Could be corrosion under SMC. If R7005 was dead then the ISL was also killed. This only happens with crap Chinese chargers like this. It may have killed the SMC also. Check for corrosion, but this may be a dead SMC.
 

WeLoveApple

New member
So I did change the ISL again. Nothing changed. Changed the SMC too. Still no green light with quarter fan spin.
The current sensing seems messed but those resistors seem okay.
Just to be sure: R7151 is around 3.5ohm instead of 2ohm respectively R7152 is around 1ohm instead of 0ohm. Could this be the issue?
 

dukefawks

Administrator
There are many more reistors then just those two, check the data lines pin 1,2,5,6. 12 resistors in total in those data lines to CPU and SMC.
 

WeLoveApple

New member
Sorry I guess I did not understand correctly what to check the first time. Those two resistors were connected to pin 8. of u6100
Anyway I just checked all the rest of the SPI resistors. All of them are fine.
 
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