I need to pass a USB cable through a vacuum chamber wall, for which we have only D-SUB passthrough flanges available. So I cut a USB cable in half and soldered a D-SUB connector to each half. For USB 2.0 connections, this works without any issues, but I've had troubles getting a USB 3.0 connection to work.
Specifically, the computer emits the connect/disconnect sound repeatedly every few seconds when the cable is plugged in. The only workaround is to push the connector in slowly, until the device is recognised, essentially forcing a USB 2.0 connection.
I assume this is due to insufficient shielding to get a USB 3.0 link?
The individual connections seem to be fine, with <3Ω resistance for each one and no shorts. Below is a diagram of how I routed the cables through the connector:
As shown in the figure, the shield is connected to the shell of the connector to connect the shield on both sides together. I tried to keep the amount of destroyed shielding low, with around 3cm on either side removed.
What is the most likely cause for this failure, and how to avoid it in the future, if possible?