820-2936 Board Not Charging, Green Light, Turning On

[mccafe]

Hello,

I have a board that turns on, but does not charge and will only run off the adaptor. I switched it with a known good battery and it still will not charge, but it can run off the battery only if I first turn it on with the adaptor connected. Green light on charger and never turns orange.

PPBUS_G3H is 12.3 volts.

There is evidence of work done to this board already from a different repair shop specifically Q7035 and Q7030 is not the original transistors and looks to be pulled from an Air board. I replaced the transistors as well as the ISL, but still get only 12.3 volts. CHGR_CSI and CHR_CSO circuitry I think is good.

Help please!

 

[JohnB8812]

Does it recognize a battery in the OS? If so measure resistance between pins 17/18 and 27/28 of the ISL6259.

 

[mccafe]

It does not recognize the battery in OS. Every time I try to check the box to enable battery percentage, it unchecks itself.

 

[JohnB8812]

Ok so then this is an issue around the SMBUS data lines. 12.3 volts means the SMC is not running. Any corrosion or signs of liquid near it? Might be a good idea to remove the edge bonding around the SMC and run flux under it with heat. Clean out any crap under it.

 

[mccafe]

Looks like the SMC was replaced or reballed before. There is little to no space in-between the chip and the board and the edge bonding is gone. I'll give it a try thank you.

 

[JohnB8812]

Ewww not fun. I'd say reflow then first to see if any change. If no change, probably bad SMC from whoever replaced it before

 

[2informaticos]

Post resistance value to ground for SCL/SDA of battery bus.
You should get less than 1% difference.
If not, remove D6950 (if present) and check again.
If still bad, possibly SMC issue...

 

[mccafe]

2informaticos, just seen your post now.

I just want to update that replacing the SMC did the job. Computer recognizes battery and it is charging.

 

[JohnB8812]

Nicely done!