Macbook A2338 820-02020

[Instafixx]

Stuck at 5V drawing a constant 0.450Amps.

PPBUS at 7-8V.
I checked and found PP1v25_s2 to be 0.280 which I think is a little lower than usual.

PP3v8_AON is 3.7V

 

[Instafixx]

RN420/1/2/3 heating up. Resistance Across Pins is 8 Ohms.

R770C across Pins is 2.2Ohms.

Bad U7700 ?

 

[2informaticos]

These readings look good.
Multimeter probes ad 1-2 ohm normally.

Do you get U8100 LDOs?

Check CD3217 chips LDOs too; voltage and diode mode.

 

[Instafixx]

Thermal imaging shows U7700 heating up slightly. Still need to check the LDOs ?

 

[2informaticos]

U8100 LDOs should appear first; is the master.
Just in case, check U7700 LDOs in diode mode too.

 

[Instafixx]

Replaced U7700. Device on now.

Got 2 cases including this in the last 1 week of A2338 stuck at 0.45V.

Both lead to U7700 .