Good news everyone.
Today came the package with my little platine.
So I did some soldering with the wires and the USB cable (and this time without problems).
PICT0043.JPG
It is only a test wiring for checking, so not final wire length or position, and it worked as I expected.
The next on my list is, powder coating of the housing.
This could take some time, because I don't do this myself.