> Hello friends.
>
> I have this a106, that I used very little in the last 8 months.
>
> I decided now to use it (well done!)
>
> But:
> I can't hear the resonance. I know very well the ms20. but my module
> is doing a very impercettible variation to the sound moving the RES knob.

Pay attention that you may "override" the resonance with a high audio input
level and extreme clipping settings (please refer to the pages 5, 6 and 10
of the user's manual). If you reduce the audio level you should discover
that the resonance is now working. If even at low audio levels the resonance
control does not have any effect please send the module to your dealer for
repair.

> Is there any trick I need to use to jumpstart the RESO > any trimmer to

trim

There is no trimming for the resonance.

> what's the white marked IC "DS20" (is an LM13600 )

It's a special, selected circuit. We do not publish details about this
circuit.

Best wishes
Dieter Doepfer