820-02016 A2337 5V Cycling between 0.00 and 0.45a

F

fixupp

New member

Jul 26, 2025

• #1

Water-damaged MacBook.
Main areas ( U8100 U7700) are not affected.
5V Cycling between 0.00 and 0.45a. Check under the thermal camera U8100 pulsing hot. PP1v8_S2 0v, no short.
Other U8100 and U770 LDO outputs are not short and pulsing.

 

2informaticos

Administrator

Staff member

Jul 26, 2025

• #2

What about PPBUS_AON and 3V8_AON behavior?

 

F

fixupp

New member

Jul 26, 2025

• #3

PPBUS_AON: 9-12.3v, pulsing when the apm is from 0-0.45a
3V8-_AON: 3v8 stable.

 

2informaticos

Administrator

Staff member

Jul 26, 2025

• #4

Test with a battery holding some charge.

What about U8100 and U7700 LDOs?

 

F

fixupp

New member

Jul 26, 2025

• #5

With battery connected. 5v and 0.45a stable.
Pbbus-aon stable at 12.35v
All LDOs are not short, and pulsing the voltage. Look like the U8100 try to turn on and off

 

2informaticos

Administrator

Staff member

Jul 27, 2025

• #6

PMUs can detect an overcurrent and restart power sequence.
Compare diode mode readings on all secondary rails with good board, or reference table.

OpenBoardData Project