00850 with one port dead

[captainmac]

I have an 820-00850 which has one dead USBC Port. Checked the ports, they are all clean.
All other 3 ports work perfectly. Customer also just worked on the machine, no issues, besides from it not wanting to go to sleep.
I cannot find any corrosion other then some dusty areas, but none of them seem to be around crucial areas.
U3200 seems to not work; when i connect charger, nothing shows on USBC Amp meter. (no bootlooping either).

Where can i start?
When i connect to the adjacent port, i get 20v for PPDCIN_G3H at q3200.
I have no luck with these devices, so some pointers are more than welcome please

 

[2informaticos]

Check diode mode to ground for CC1/2 pins of corresponding USB port.

 

[captainmac]

CC1 reads 0.2649 and CC2 reads 0.2650 (both with red probe to ground)

 

[captainmac]

OK after checking those points, i reconnected the charger to the port, and it is now taking 5V and .240 Amps... weird.

 

[captainmac]

LDOs are all there, except BMC 1v1 LDO. Does this mean i need to replace the CD3215? It's underfilled, so i'd rather not of course.

 

[2informaticos]

Be aware, 1V1 LDO must appear on the powered port only .

 

[captainmac]

yes i understand.
I power the port corresponding to U3200, it's taking 5V @ 240amps and all LDOs appear except for the 1v1 LDO.
Is there anything i should check before starting to replace U3200...?

 

[captainmac]

bump

 

[2informaticos]

As you cannot find any bad reading on chip rails, should change it.
Be sure all surrounding resistors (pages 29/30) and traces are good.

 

[captainmac]

damn. ok im going to try, the underfilled crap on this board is driving me nuts though.
I use a Qianli prying tool to remove most of it, but desoldering the chip is darn hard: feels like i'm ripping off the chip rather than desoldering it gently...
any tips by any chance?

 

[captainmac]

OK, just replaced the chip with a new one; now i get 5v on all ports...goddammit

 

[2informaticos]

So none of USB-C ports work now?
Something got affected by heat, or you may have broken traces.
Also is possible to have bad solders of CD3215 chip.

 

[captainmac]

Yes, before replacing the U3200, it would start on all other 3 ports. Now, all ports are asking 5v and using 0.2 amps.
I'm going to go over the entire thing once more and keep this thread updated.

 

[2informaticos]

The original chip was communicating correctly with SMC, but had a problem communication with the charger.
The recently soldered chip fails the communication with SMC.
This is the reason why SMC do not allow any other port to switch to 20V.

 

[captainmac]

OK, so i assume i can try a different CD3215 or check traces to SMC firstly.?

 

[2informaticos]

Not only to SMC.
God knows which other trace may blcok CD3215 chip from working good.

Be sure all surrounding components are in place and in good condition.

 

[captainmac]

alright, it's fixed, i swapped the CD3215 with one i reballed (i used new preballed ones, but apparently they never work as opposed to the ones i get from donors)
and the Mac works fine again.
Thanks for the support!

 

[captainmac]

If anyone has good tips on how to remove underfill: more than welcome. I watched Tim Herman's video (you're great at that stuff dude) but somehow my underfill-removal always ends up fucking messy.
do you guys use heat while removing the underfill? what tools?