820-3332 No SMC_BC_ACOK current sensing issue


Hi there,

BOard came in and upon inspection, c7026 and c7050 were broken from board. I believe they must've caught on the edge of the battery when installing the logic and somehow just now finished off after some time as this mac was running for few months. Those have been replaced and so has the ISL (3 times now) as all other voltages around ISL seem correct and resistance looks good:

pin 1 - 0v
pin 2 - 16.5V
pin 3 - 4V
pin 9=0V
Pin 12 =3.4V
pin 13 = 3.1V
pin 14 = 0V
pin 17 =12.3V
pin 20 = 5.5V
pin 27= 16.1V

resistance pins 17/18 at ISL pins is 3.9 ohms and 27/28 is 21.6 ohms.

I noticed R7051 was discovered to be high and replaced and again did the same so not sure if that was related to bad ISL but seems to be ok now.

I replaced q7080 also. My best guess is there's detected current sense issue. SMC_BC_ACOK diode red to ground is .45V.,


Staff member
ACOK signal informs SMC about charger presence; is not current sensor related.

Post voltage and diode mode to ground on SCL/SDA lines of battery bus,
Be sure to use original 85W charger.


Oh ok. I guess I thought the ISL wouldn't send smc BC ACOK unless current sensing was correct.

both lines show 3.41v.

diode red to ground SCL is .525V SDA is .521.


This board can kiss my ass. Issue was related to U6901 apparently was pulling down SMC BC ACOK? once powered? Anyway after pulling it and putting it back I got intermittent SMC_BC_ACOK signal. Replaced it and signal was solid 3.3V but then pPBUS GH was no longer 12.3V and flaking around 5V. I thought it was related to Q7030/5 so swapped those out with no change... changed the ISL AGAIN and board starts and boots. FUck this board. haha


This one got the last laugh as it turned out it was not fixed after all. I ended up swapping the SMC. I would really like to kick this thing into the parking lot. :)