Synth-DIY Yahoo! Groups Archives

Thread

A-198 Ribbon pressure offset (zero)

2016-11-22 by synth@sb3d.com

I am using the A-198 with a frac setup, originally powering from a +/-12V supply but now trying to run it off of the +/-15V supply. It does work fine with just one exception. The pressure voltage now has a 3V offset. No finger on ribbon, panel pot fully clockwise, I get 3V. More if I press. How can I adjust this? Is that what the trim pot is for?

Thank you

Steve B

AW: [Doepfer_a100] A-198 Ribbon pressure offset (zero)

2016-11-23 by yahoo@doepfer.de

The trimming pot on the A-198 pcb can be used to adjust the pressure CV
offset. But I'm not sure if the range is sufficient to compensate the offset
in case of a 15V supply. You have to try out.

Best wishes
Dieter Doepfer

Show quoted textHide quoted text

> -----Ursprüngliche Nachricht-----
> Von: Doepfer_a100@yahoogroups.com [mailto:Doepfer_a100@yahoogroups.com]
> Gesendet: Dienstag, 22. November 2016 23:48
> An: Doepfer_a100@yahoogroups.com
> Betreff: [Doepfer_a100] A-198 Ribbon pressure offset (zero)
>
>
> I am using the A-198 with a frac setup, originally powering from
> a +/-12V supply but now trying to run it off of the +/-15V
> supply. It does work fine with just one exception. The pressure
> voltage now has a 3V offset. No finger on ribbon, panel pot fully
> clockwise, I get 3V. More if I press. How can I adjust this? Is
> that what the trim pot is for?
>
> Thank you
>
> Steve B

Re: AW: [Doepfer_a100] A-198 Ribbon pressure offset (zero)

2016-11-23 by synth@sb3d.com

Oh good, I was hoping it would be that. You are right that the range is not sufficient so here's what worked for me. Adjacent to the trimpot are two 10K resistors. Ignore the one that's by itself and tack a 27K resistor across the the one that's on the end of a group of four (can't read the number as it's under the part). That gave enough range to dial it in.

Thanks for that info Dieter!