820-00840 Burned U3200 USB-C controller

aplas

New member
5V 0A on first USB-C connector
5V 0,29A on second

Removed U3200, cleaned the mess, made sure leaded pads not shorted.

we have short on cpu lines:
L3200 USB_UPC_PCH_XB_N and USB_UPC_PCH_XB_P - shorted to ground
L3000 USB_UPC_PCH_XA_N and USB_UPC_PCH_XA_P - shorted to ground

Is it worth putting new U3200 or it's dead cpu and it's RIP time?

I appreciate your knowledge and time, many thanks!
 

2informaticos

Administrator
Staff member
Apple schematic is a nightmare in tjis case.
Is not clear at all where the lines go.
=USB_UPC_XB_P is same as USB_UPC_PCH_XB_P and NC_USB2_08P.
Last one goes to CPU in schematic, but also has "NC" marjing (Not Connected).
There also appears USB_UPC_XB_P, connected to ground through R3014; but not directly related with =USB_UPC_XB_P in schematic.

You should compare with working board, to discard any doubt.
Just in case, remove R3014 and check if =USB_UPC_XB_P is still shorted to ground.
If yes, then bad CPU.
First look at USB redriver chip, if exists in your board; search the forum about it.
It could be connected there too and many times dies together with one of CD3215 chips.
 

aplas

New member
After removing R3014 =USB_UPC_XB_P is not shorted to ground.
but it still has short on these lines:
at L3200 USB_UPC_PCH_XB_N and USB_UPC_PCH_XB_P
at L3000 USB_UPC_PCH_XA_N and USB_UPC_PCH_XA_P

PI3USB32 seems clean not damaged. But did not find in forum how to inspect that chip.

What should I look for on good working board?
 

2informaticos

Administrator
Staff member
Inspect for any small hole on top of redriver chip; or other sign of burnt.

If you still have short after removing R3015, then bad CPU.
Or redriver, if is connected there...
 

aplas

New member
R3014 and R3015 lines are not shorted after remove.
Redriver has no visible signs (inspected under 45x microscope) of burn or damage.
Is there a way to test redriver or should I remove it and then check the shorted lines or just replace?
 

2informaticos

Administrator
Staff member
Do you still have short on any of above mentioned lines?
If yes, then bad CPU; or redriver, if connected there.
If short value is very low you, can probably heat the culprit injecting voltage.
 
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