SOLVED: 820-02016 - Only 1 USB C port boosts to 20V and no USB activity on either

[SoloHarty]

Hi,

got an M1 MacBook Air on the bench. Unit is extremely clean with no signs of a drop or liquid. Unit will power on as normal but will only charge NORMALLY from the USB C port closest to the user. the other port stays at 5V 0.3-0.4A and no cycling (CORRECTION - unit CHARGES at 5V3A when plugged into the port closest to the screen and unit is switched on).. both ports do not have USB activity when plugging something in. I have tried 2 new port flexes and I cannot see any short on the lines at all. What could I be missing?

Any help appreciated.

 

[2informaticos]

Compare diode mode readings around both CD3217 chips.
Start with their LDOs.

You should try to change the chip blocked on 5V anyway.

 

[SoloHarty]

SOLVED - Replaced both CD3217 chips and all functionality came back. Bit of a strange one as no liquid anywhere on the board.

 

[SoloHarty]

SCRATCH THAT: USB ports function fine for USB DRIVES only. Will not see a mouse, keyboard or customers MIDI devices but will see and boot my MacOS installer drives no problem.... This is in OS and also on Boot menu. strange

 

[2informaticos]

So USB 2.0 not working.
Check corresponding lines in diode mode.

 

[SoloHarty]

OK DEFINITELY solved this time around. one of the lines from L500 was pulled to ground. Replaced CD3217 again and all is working as it should. Thanks for the help 2informaticos!