820-01521 - Bad to worse

[rvanpruissen]

Repair attempt 1:
Recently fixed this one after minor water damage. Replaced the RIO because of crackling sound. Tested it, everything seemed to work.

Repair attempt 2:
Got it back because it wouldn't wake up on occasion. Measure around for a bit and found SMC_LID_RIGHT and LID_OPEN_RIGHT to be .45V when the MB was open. This should be 1,5v on a normal board. Ended up tying SMC_LID left and right together to ensure SMC_LID_RIGHT going to 1,5v when open. I have my doubts about this fix, but seemed to work at the time.

Repair attempt 3:
MacBook turned off suddenly according to the customer. When I got it, the charger showed 20v with amps jumping from 0 to .08 and back and the T2 chip felt a bit warm to the touch and of course no boot. After removing the aforementioned jumper and ultrasonic, now the board is stuck on 5v charging, again cycling between 0 and 0.08A. LDO's measure fine, PP3V3_G3H is present. With the jumper removed and just the bare board, SMC_LID_RIGHT and LEFT both are at 1,5v with nothing connected (as before).

 

[2informaticos]

Something happened on USB-C areas.
All the ports have the same behaviour?

 

[rvanpruissen]

No, cd3215 area looked clean before ultrasonic. All ports act the same.

 

[2informaticos]

Did you use sweep option on ultrasonic process.
Be aware, ultrasonic cleaner can knock off components, or break traces.
Sweep option must be used, to avoid hot-spots.

Do you get 1V1 LDO at both CD3215 chips?

 

[rvanpruissen]

Yes, it sweeps, not optional on mine. 1V1 missing on U3100, present on the other CD3215.

 

[2informaticos]

Then change U3100...

 

[rvanpruissen]

Fixed it.

 

[2informaticos]

Any feedback about the solution?
Was bad U3100???

 

[rvanpruissen]

Yes, that's what I meant to say: changing U3100 fixed it.

Strange one because all earlier problems had nothing to do with the cd3215s. Must have been some corrosion I missed or something.