820-00850 5V DCIN all LDOs present

[Rlab]

Hi guys,
I got this mac with a little water damage in the QB631 area and RB641 & RB631 were replaced.
I have 20v in DCIN only with the battery connected but it does not turn on. without the battery DCIN has 5V and all LDOs are present.

checking without battery i have:
PPBUS_G3H 12.28 V
PP5V_G3S 0.033 V
P5VG3S_EN 0.0 V
PP3V3_G3H_RTC 3.3 V
PP3V3_G3H 3.3 V
PP3V3_S4SW_SNS 0.0
PP3V3_G3S 0.0
P3V3G3S_EN 0.0

No shorts..

bad U7800?
any ideas?

 

[2informaticos]

12.28V at USB-C input denotes a communication problem between T2 and CD3215 chips.

All USB-C ports have the same behaviour?
Compare diode mode readings for LDO rails of all CD3215 chips; also for CC1/2 pins.

See if you can get into DFU mode.

 

[Rlab]

yeap, all USB-C ports have the same behavior. 20V with battery and charger only 5V just charger.
no shorts found, all diode mode readings are ok in LDOs.

CC1/2 pins. ? what is it?
anything else to check before the T2 firmware ?

 

[2informaticos]

CC1/2 means CC1 AND CC2.

 

[Rlab]

USBC_XA_CC1 0.569
USBC_XA_CC2 0.562

USBC_TA_CC1 0.566
USBC_TA_CC2 0.572

USBC_TB_CC1 0.559
USBC_TB_CC2 0.565

USBC_XB_CC1 0.557
USBC_XB_CC2 0.563

what do you think?

 

[2informaticos]

Not too big differences.
Do you get 1V1 LDO on each powered USB-C port?

 

[Rlab]

yes, i have all LDOs present, 3.3 1.8 (X2) and 1.1 ( on each port where power is connected)

What could be the reason for 20V in DCIN when battery and charger connected but 5V with only the charger connected?

 

[2informaticos]

Did you try DFU?

 

[Rlab]

2informaticos !!!!
mil gracias !!!

So the T2 firmware fix procedure did the magic.
This mac is now up and running.