00928, trying to save some time

[captainmac]

Long time no speak, how are you Vali? took some vacation?

Have a 820-00928 here that came in for no power/5V on all ports

Saw a blown diode at DB504, which helped me suspect UB300 (also, it lit up under thermalcam) : replaced UB300 with a good CD3215.
Now my results are as follows, when connecting power to respectively:

U3100: 20V, computer is alive and running
U3200: 5V, virtually no amp draw
UB300: 20V, computer is alive and running
UB400: 5V, virtually no amp draw

I don't want to just replace any chips without making sense of this: what is a commonality between the working CD3215s and the not working ones?
Where would you start?

 

[2informaticos]

Thanks for asking.
I was 3 days to Ibiza, not for vacation.
Today I'll go back for a week; maybe this time I find time to wash my feets on the sea!

Compare diode mode readings around CD3215 chips.
Pay atention to LDOs and CC1/2 lines.
Good to have S-UEM2 for USB-C connectors test.

 

[captainmac]

Sounds good man, hope you do. always wanted to go there, love the medditeranean sea!
Have fun and relax!

Yeah you're right i'm going to do some measurements and let you know how it goes.

 

[captainmac]

OK after looking at all LDOs, CC lines (and seeing nothing off) I decided to also replace the other 3 CD3215s since i had a fully working donorboard with 4, and i wanted to take a shortcut i guess:
My results now at the different ports:

UB300 5V 0.3A, bootlooping, all LDOs high
UB400 5V 0.0A, board is unpowered (even 3v3 is gone)(maybe this is some anomaly with my USBC meter, but i don't see this often)
U3100 5V 0.3A, bootlooping, all LDOs high
U3200 5V 0.0A, board is unpowered (even 3v3 is gone)

 

[2informaticos]

Something happened in the replacement process; you had two working ports before.
All 4 input fuses are OK?

If a CD3215 chip gets 5V input, it should deliver voltage on its LDOs.

 

[captainmac]

OK i cleaned and rechecked all my work, apart from a tiny bit of adding solder to R3078 pin 1 which seemed loose, didn't do anything, and of course
Now everything works.
Knew my CD3215s were good!