A2141 820-01700-A MacBook Pro 16” with missing USB data

[sekidata]

This 820-01700 board arrived with a single misbehaving USB-C port. I found a shorted CD3215, which I replaced with a location-matched chip from a donor board. Now all 4 ports charge the battery and power external USB drives but don’t allow for any data transfer.

External drives are recognized on startup, before the drivers are loaded. I also get periodic kernel panics which trace to iokit.IOUSBHostFamily.

I’m familiar with this exact issue from the older A1708 model, where a bad USB redriver chip was to blame. How do I troubleshoot it in this model?

 

[2informaticos]

Once macOS is started, U2800 and UB000 control the ports.

 

[sekidata]

Since all 4 ports are nonfunctional, are both U2800 and UB000 likely defective?

 

[2informaticos]

Strange, but that should be the issue, if all ports work before loading macOS.

 

[sekidata]

I replaced U2800 and UB000 and the situation is unchanged.

 

[2informaticos]

The chips get correct power rails?

 

[sekidata]

Yes, the 0.9V and 3.3V rails are there.

 

[sekidata]

After performing a DFU Restore, I'm now seeing a short to ground on PPBUS_HS_CPU. Looks like the CPU shorted out for good - the USB issue was probably a pre-failure symptom. Goodbye board.