Macbook A2442 motherboard 820-02098 no power on no green light

This Macbook comes dead without any liquid damage.
I found some coils burned near headphones jack, and CS42L84A was shorted and replaced.
But the machines doesn’t turns on and no green light.
I can’t find any other shorted components.

Please post a clear photos of the PCB area where the burnt components were found, along with surrounding area of replaced audio chip.

Your photos are too blurry to determine which resistors are in place and which aren't. Please upload some better photos, ideally from under the microscope. You said that you do not get a green light on the charger's tip, so please connect the USB-C charger to one of USB-C ports via USB Type C tester (like the one depicted below) and provide the voltage and amperage readings.

Sorry but I haven’t a microscope camera, only microscope.
Voltage is 5,2V
Amperage is (when connected) 0,450A and after some seconds is 0,370A

I got these voltages:

Do you have a thermal camera? If so, post a thermal image of both sides of the board with the heatsink removed.

Actually I don’t have it

I checked PP0V72_S2_VDDLOW Line with resistance of 0,45Ω no voltage.


connecting power in USB-C after some minutes comes very little warm U0600 and just a little more U7700

Is it possible to inject 0,72V on this line?

valieromarco писал(а):Is it possible to inject 0,72V on this line?

Yes, perform a short circuit test on this power rail with a voltage limit of 0.72V.

I made the test injected 0.7V I got 4 ampere, nothing becomes hot.
Slowly amperage goes down now is 3 ampere.

During a short circuit test, measure the voltage at the end of the test wires (at the point where the wires are soldered to the board).

0,47V

At this voltage you have a power loss of about 1.5W and something should get at least a bit warm.
Pay special attention to the chip U7700 and the APU.

Nothing becomes hot or warm
Amperage now is 1,2A

Remeasure the resistance to ground on the rail "PP0V72_S2_VDDLOW".

0,54 ohm

Set your multimeter to the diode test mode and measure the voltage drop to ground on the rail "PP0V72_S2_VDDLOW" with both polarities of test leads.

You mean red tip on the ground and black tip on 0,72 rail and vice versa on diode mode?
If so both 0.020

Yes, exactly.
Something on this power rail is shorted to ground. Most likely the APU or chip U7700.

Remove the resistors R25B4 and R25B5 from the board and remeasure the resistance to ground on power rail "PP0V72_S2_VDDLOW".

0,60 ohm

One of the chips - U7700 or the APU is damaged almost for sure.
Without a thermal camera is difficult to determinate which one. The option is to remove one by one from the board and check the resistance to ground after removal.

In my opinion is more likely the APU.