Doepfer

> Two of my A-131 log VCAs from 1999 have the same problem:
> The initial gain control (top pot) barely works at all. I have swapped
> the modules for other working VCAs to isolate the problem to the
> module itself and not the bus or rack. I even swapped the IC1 and IC3
> from one to another without any luck.
>
> The modules are the CEM version I believe, and there is no sign of any
> component having failed. All  the other features work, but when you
> apply a CV to CV1-in or CV2-in then the initial gain control does have
> an effect.
>
> I am wondering whether this is a common problem with the CEM chip or
> if anybody else has had similar problems.
>
> sean

You have to consider that the A-131 has an exponential control scale, i.e.
the manual control has only little effect in the lower range of the initial
gain control because of the exponential control scale. But if you turn the
control fully clockwise  the gain should increase clearly and reach an
amplification close to 1 in the fully clockwise position.

Best wishes
Dieter Doepfer