Luckily the 'problem' only affect a small group of A-190-3-owners, but here is Dieter's statement:
" Dear members,
We discovered that our manufacturer made a mistake during the last series of the A-190-3 production.
The USB interface of the modules were not tested correctly.
If your A-190-3 is not recognized by the computer you probably received one of these faulty modules.
Modules with these test labels are affected:
The Midi interfaces of these modules work as they should.
Only the USB interface is affected (because two capacitors have been assembled in the wrong way).
Please return the module to the dealer where your purchased it for free replacement and free shipping charges.
Please accept my apologies for this fault.
Maybe we will have to check more control samples in the future.
Dieter Doepfer "
If you are lucky enough to have an A-190-3 that doés work, don't forget to check out THIS POST about the somewhat hidden arpeggiator.
(I believe this arpeggiator function is still not mentioned in the manual or on the Doepfer website)