820-3787: Not recognizing battery

[macRepairAmb]

I have this board that's not recognizing the battery but once i power on the computer with a magsafe, i can then run the system without the magsafe. On the display, it's not showing the battery.

I've replaced the SMC and U7100. I've also check check R7151/2, and R7121/2

 

[2informaticos]

Post voltage and diode mode to ground at SCL/SDA lines of battery bus.
Remove D7050, if present...

 

[piernov]

Check what it says about the battery under System Profiler.

 

[SMMRepair]

Try another battery first, of course.

 

[macRepairAmb]

SMBUS_BATT_SCL - 0.649(1.66v steady). Same readings with D7050
SMBUS_BATT_SDA - 0.55/(Voltage reading bounces between 3.4 and .22). With D7050 removed, it does the same thing on voltage reading and has same diode reading.
This is interesting because before the SMC replacement, both voltages, though the were low (not 3.4), they were steady and not bouncing about. I did have a very low resistance measurement at the time, in the ohms level and not the 11kohm level that i'm at now. Wondering if this smc is defective as well. Before i go buying another set of donor boards, is there anything else i should check?

Battery profile so "no" for battery connected.

And i did try with a new battery also.

 

[2informaticos]

Diode mode on these lines must be very similar, less than 1% difference.
Did you check that before changing SMC?

 

[macRepairAmb]

Unfortunately i didn't check the diode readings after i had got very low ohm resistance measurement on both lines. I proceeded to Pulled the smc to check for crap that may be underneath and then noticed resistance went up into the Kohms.

 

[2informaticos]

You should check these values without SMC, once out of board.

 

[macRepairAmb]

with SMC removed,

SMBUS_BATT_SCL - 0.65
SMBUS_BATT_SDA - 0.55

I checked resistors R5380 and 5381, both are good at 2K.

 

[2informaticos]

Too big difference; hope you checked both lines when board got cold.
Remove ISL6259 and check again.

 

[macRepairAmb]

You've saved the day again. So it appears the ISL6259 chip (which was a new chip and not from a donor board) that i had replaced earlier was also defective. Now both lines are reading 0.55 and the board now recognizes the battery.

Thanks again for the assist.