Doepfer

> Hi list,
>
> I have been taking some detailed measurements from my A-127 (for
> comparison against a heavily-modified Plan B M12) and have
> noticed that one of the three sections is adjusted quite
> differently from the other two, which agree very closely. Thus
> I'm not sure which sections are adjusted as they would have been
> when I originally bought it (it's likely I have 'fiddled with it'
> over the years!), so if anyone has the service manual and can
> detail or send me the calibration procedure I would very much
> appreciate it!
>
> Many thanks,
> Tim

There are four trimming potentiometers on each A-127 board:

P6/100k: frequency offset (defines the absolute filter frequency when the
VCF Frq. control is fully CCW)
P7/2k5 : frequency scale (defines the sensitivity of the CV input, can be
adjusted e.g. to approximately 1V/oct)
P8/100k: OTA offset 1 (adjusted for minimal CV feedtrough)
P9/100k: OTA offset 2 (adjusted for minimal CV feedtrough)

This is the order of the trimming potentiometers from left to right on the
pcb (front view): P7, P6, P8, P9

Hope this helps

Best wishes
Dieter Doepfer