820-00923 no activity on ampmeter

[dudipupan]

Hi there,

after some time of inactivity i'm back
I got some problem with an MBP 2017 4TBT here.
It doesn't show any signs of liquid damage but was obvisously opened before.
First step was checking amp and voltage with ampeter but there the charger does not even turn the ampmeter on - on all 4 ports.
I aready tried a known good charger and a known good USB-C Connector.

I would be very thankfull for some ideas wha could be the problem here.

Thank you

 

[2informaticos]

First check input fuses; F3000/1 and FB200/1.
Next check diode mode to ground on CC1/2 pins of all CD3215 chips.
Remove USB-C connectors and inspect their terminals for corrosion.

 

[dudipupan]

Thank you for your reply

The input fuses are all good.
For the CC1/2 pins i got the following mesurments (in ohm):

USBC_TA_CC1	19.0
USBC_TA_CC2	15.0
USBC_TB_CC1	7.7
USBC_TB_CC2	127.9
USBC_XA_CC1	19.3
USBC_XA_CC2	4.1
USBC_XB_CC1	2.0
USBC_XB_CC2	15.0

 

[dudipupan]

Sorry, you asked for diode mode measurents. Here they are:

USBC_TA_CC1	0.031
USBC_TA_CC2	0.024
USBC_TB_CC1	0.014
USBC_TB_CC2	0.197
USBC_XA_CC1	0.031
USBC_XA_CC2	0.007
USBC_XB_CC1	0.004
USBC_XB_CC2	0.025

 

[2informaticos]

Seems that all chips are bad.
Did you inspect USB-C terminals?

 

[dudipupan]

Yes, all terminals ae looking good - no corrosion or dust or any damage.
So I should start replacing the CD3214 Chips...?

 

[2informaticos]

Remove one and check if short/low ressitance disappear from its corresponding CC1/2 lines.