Vintage Synth Repair

After looking at the pics I don't believe the basic portion of the
interface is DIY. The PCB looks like an industrial design to me (very dense
traces).

Theory: The core of the interface is universal and the added PCB with the
pots is used to accomodate different synths (there might be another PCB for
the Odyssey, Pro One...).

As far as the functionality or lack thereof goes: I seem to recall that
some (most?) of the interfaces for the Mini required that a key is pressed
(or even pinned?) on the Mini's keyboard (the highest? the lowest? can't
recall).