A1989 unable to start investigating due to USB C Port fluctuation

[Daffy_ED9]

Hi Community,

got a A1989 that shows a strange behaviour while powering up.

USB C Port 1 is stable 5 V at 0,170A draw
USB C Port 2 5V with fluctuating draw jumping from 0,47A down to 0,045A and repeating
USB C Port 3 5V with fluctuating draw jumping from 0,47A down to 0,045A and repeating
USB C Port 4 5V with fluctuating draw jumping from 0,47A down to 0,045A and repeating including rebooting of port

With the thermal camera i was able to identify one CD3215 which is roughly 20 degrees warmer then the threee other ones, reading roughly 50 degrees C.

Also I have identified ELC180 chip to be also pulsing when USB is plugged in.
Video below:

Board is perfectly fine, no liquid spill or any visible damage identified so far.

I have not found any advice on an identical behaviour so far, and am looking forward for your advice

 

[2informaticos]

First of all, welcome to the forum!

Any history available?

Post voltage and diode mode readings on the 4 LDO lines of each CD3215 chip.
Be aware, 1V1 LDO BMC should appear only on the powered port.

 

[Daffy_ED9]

Laptop was purchased as broken, so unclear what happened.
First initial readings attached:

UB300
LDO BMC 0
LDOD 1,1 to 3,9 flucuating
LDOA 1,1 to 1,8 fluctuating
PP3V3 UPC TA LDO 3,1 V

U3100
LDO BMC 0
LDOD 1,7 V
LDOA 1,8
PP3V3 UPC TA LDO 3,2 V

U3200
LDO BMC 0
LDOD 1,7 V
LDOA 1,8
PP3V3 UPC TA LDO 3,2 V

UB400
LDO BMC 0
LDOD 1,7V
LDOA 1,7V
PP3V3 UPC TA LDO 3,3 V


Actually I´m measuring a short on CB300 and CB400, C3100 and C3200 PP3V3_G3H_RTC

Can u help me out on where to get the diode measured please?

 

[2informaticos]

Change UB300...