MacBook A2141 - Not charging

[overshoot]

Hi,
I have that board 820-01700 that is not charging.
Laptop is turning on with charger plugged in.
It will also work on battery but will not charge the battery.
I am getting 20V with 0A drawn when battery is plugged in on all 4 ports.
However I got it to charge for a few seconds and then it stopped.
Battery level is detected by the system.

After inspected the board, I've found a blown cap on PPBUS_G3H near the ISL chip.

I am kind of at a lost on where to start diagnosing.
If board starts with no battery, CD3217 are working fine I assume.
So I am tempted to blame the ISL.

Shall I go ahead and replace that chip first or I am on the wrong path?

 

[2informaticos]

Tested with known good battery?

 

[overshoot]

Yes I did. I tested 2 different batteries and used my test mainboard which was able to charge the customer’s battery

 

[2informaticos]

Short R6950 pads and check if works then.

 

[overshoot]

No change

 

[2informaticos]

Did you keep the short there?
Not only temporarily contact...

 

[overshoot]

Yes I did indeed. I understand it's to make sure the battery is forced detected by the system.

 

[2informaticos]

Check voltage and diode mode on I2C_PWR_SCL/SDA lines.

 

[overshoot]

Those 2 lines are at .47V drop to ground.
Voltage with charger and battery plugged will oscillate between 1.5V and 1.7V for both lines.
When I reconnect the battery, the battery will start to charge and when the amperage reaches 3A or so, the charger will reset (USB-C meter switches off then on again) and seats at 20V 0.04A.

I went ahead and check the current sensing resistors. All check fine.
Then I went ahead and replace the ISL from the same board (donor) and nothing changed.

Since the charger reset itself, is it possible the issue is in the USB-C circuitry?

 

[2informaticos]

Did you test if battery is charging connecting the charger directly to the port?
Some USB-C meters restart if current goes over 3A.
BTW, use 96/140W charger; required for this model.

 

[overshoot]

Did you test if battery is charging connecting the charger directly to the port?

What do you mean?

I’ve seen my usb-c meter resetting sometimes but it’s closer to 4-5 amps. And it should restart charging then which in this case it doesn’t.
I am indeed using a 96W charger.

 

[2informaticos]

I mean connecting the charger directly to MacBook's USB-C port; without using USB-C meter.

 

[overshoot]

I did that already no change.

 

[2informaticos]

You may have problems with U7800, or T2.

Just in case, save data and try DFU restore.