820-00928 5v looping one side only

[wgaca]

Hello,
I'll give a quick description of the original damage and what I've done till now and then provide some measurements.
I've attached photos with the initial damage and after removing the short on the trackpad connector.

Initially, PPVIN_S4_TPAD_FUSE was shorted and the short was removed by digging 2 holes in the board.
PP3v3_G3H was shorted as well but after injecting current it went away immediately.
I had 5V looping on 2 ports so i reflowed one of the CD3215 (UB400) and now I had 5V stable. I replaced the chip with another one C00 but same 5V stable
I then checked the other 2 ports and they are looping 5V now.
I replaced both CD3215 (U3100 and U3200) on the looping side with no change. So here are the measurements now (After cleaning and drying the board)

Charger Connected to U3200

PP3v3_G3H - 3.3V Looping
PP20V_USBC_XB_VBUS - 5.15V Looping
PP3v3_UPC_XB_LDO - 3.3V Looping
PP1v8_UPC_XB_LDOD - 1.8V Looping
PP1v8_UPC_XB_LDOA - 1.8V Looping
PP1v1_UPC_XB_LDO_BMC - 1v1 Looping
SMBUS_SMC_4_G3H_SDA - 3.3V Looping
SMBUS_SMC_4_G3H_SCL - 3.3v Looping
TBA_VDDA - 5V Looping
USB_XB_CC1 - 0V
USB_XB_CC2 - 0.98V Looping

Charger Connected to U3100

PP3v3_G3H - 3.3V Looping
PP20V_USBC_XA_VBUS - 5.15V Looping
PP3v3_UPC_XA_LDO - 3.3V Looping
PP1v8_UPC_XA_LDOD - 1.8V Looping
PP1v8_UPC_XA_LDOA - 1.8V Looping
PP1v1_UPC_XA_LDO_BMC - 1v1 Looping
SMBUS_SMC_4_G3H_SDA - 3.3V Looping
SMBUS_SMC_4_G3H_SCL - 3.3v Looping
TBA_VDDA - 5V Looping
USB_XA_CC1 - 0V
USB_XA_CC2 - 0.98V Looping

Charger Connected to UB400

PP3v3_G3H - 3.3V
PP20V_USBC_TB_VBUS - 5.15V
PP3v3_UPC_TB_LDO - 3.3V
PP1v8_UPC_TB_LDOD - 1.8V
PP1v8_UPC_TB_LDOA - 1.8V
PP1v1_UPC_TB_LDO_BMC - 1v1
SMBUS_SMC_4_G3H_SDA - 3.1V - 3.3V
SMBUS_SMC_4_G3H_SCL - 3.1V - 3.3v
TBA_VDDA - 5V
USB_TB_CC1 - 0V
USB_TB_CC2 - 0.98V

Charger Connected to UB300

PP3v3_G3H - 3.3V
PP20V_USBC_TA_VBUS - 5.15V
PP3v3_UPC_TA_LDO - 3.3V
PP1v8_UPC_TA_LDOD - 1.8V
PP1v8_UPC_TA_LDOA - 1.8V
PP1v1_UPC_TA_LDO_BMC - 1v1
SMBUS_SMC_4_G3H_SDA - 3.1V - 3.3V
SMBUS_SMC_4_G3H_SCL - 3.1V - 3.3v
TBA_VDDA - 5V
USB_TA_CC1 - 0.98V
USB_TA_CC2 - 0V

I replaced both U3100 and U3200 and they are still looping.
Obviously i can't confirm 100% the CD3215C00 I used are good but i don't have any more on hand at the moment to keep on replacing them.
Is that a CD3215 issue or it can be something else?

Summarised:
2 USB ports are looping at 5V the other 2 have stable 5V. The looping kept even after replacing both of the cd3215
I have no thermal camera and i can't feel any of the USB controllers to get warm.

 

[2informaticos]

First of all, welcome to the forum!

The looping ports should be good.
This symptom appears because board try to starts and something else trigger a protection when try to switch to 20V.
You must work on the "fixed" ports, there is a problem...

 

[wgaca]

Do you mean I have a problem with the 2 that are not looping?
If so, I just replaced both of them with the original CD3215's i had and they are still not looping.

Isn't it when a port is looping it's the issue and when it isn't it's OK?
Also referring to

I also tried to replace the USB rom on both sides and i still have the same results



EDIT:

Taking out U3200 makes U3100 have stable 5V. Once I replace U3200 with another chip both start looping again.
The other 2 ports stay at stable 5V

 

[2informaticos]

Did you take USB ROM from donor board?

How much voltage did you inject on 3V3_G3H?
Did you find the short, or just noted went away?
If a chip was shorted on 3V3_G3H and is still on the board, it can have other pins which block some data lines.
It may have power rail internally burnt/open, but can block communication for other chips...

 

[wgaca]

Did you take USB ROM from donor board?

How much voltage did you inject on 3V3_G3H?
Did you find the short, or just noted went away?
If a chip was shorted on 3V3_G3H and is still on the board, it can have other pins which block some data lines.
It may have power rail internally burnt/open, but can block communication for other chips...

I injected under 3V. It went away the moment i injected it and it stopped draining current in split second.
I will replace the SMC and report back as it had originally had a liquid sign on top of it.

Is there anything else that might cause U3200 to be the only CD3215 causing 5v looping and once removed none of the other controllers loop anymore?

 

[2informaticos]

Diagnosing USB-V areas is not easy job.
And liquid spill is the worst case, as various BGA chips can be affected by (probably) crap accumulated underneath.

Usually, cycling every 5s is sign of board tries to boot on that port.
Some sensor is then triggered and SMC resets the power sequence.

Any reason to quote an entire post visible few centimeters above?
Please, maintain forum aesthetic...

 

[wgaca]

I am sorry I just clicked reply. No other reason.
I replaced the SMC, exactly the same behavior.

The original liquid damage was affecting only the middle of the logic board, both sides that contain the USB controllers were untouched.
Is it worth stocking another 4x CD3215's and replacing all of them together?
Any guidance on how to proceed to diagnose this is appreciated.

 

[2informaticos]

Liquid on the centre is bad; CPU can be dead now.
At least one USB-C area has been affected too, as you have different USB behaviour left to right.

 

[wgaca]

Update:

U3200 LDO measurements to ground with diode mode compared to the rest

PP3v3_UPC_XB_LDO = 1647 (the other three measure approx 440)
PP1v8_UPC_XB_LDOA = 1385 (the other three measure approx 460)
PP1V8_UPC_XB_LDOD = 1379 (the other three measure approx 423)
PP1v1_UPC_XB_LDO_BMC = 0L (the other three measure approx 455)

 

[2informaticos]

Looks like U3200 is not really soldered on the board.
Reflow it...

 

[wgaca]

Just a quick update. Turns out i was measuring that specific chip with the probes the other way around It's all good.
I ordered and replaced all 4 CD3215's just to make sure that's not the issue. Still, the same 2 ports are looping

At this point, it's not even about fixing the board. I just want to know what is causing it

 

[2informaticos]

Do you get now similar readings on all CD3215 chips?
You could have a problem witht the ROM chip, or USB 3/Thundernolt controller from that USB-C area.
Maybe bad traces, solders...