MOTM

On Wed, Nov 14, 2012 at 4:35 PM, gooboworks <andy@...> wrote:

 

Ok, I have more information.

It appears that the 1v/octave and the FM2 inputs and their respective pots are working correctly.

I have more info on the problem. Whenever the EXP/LIN switch is in the EXP position, the FM1 pots has no affect along with the FM1 input voltage.

I noticed another issue. The SINE wave sounded harsh and it is hot, it measures +14v to -14v. Definitely something wrong there.

Any thoughts appreciated.

Thanks
Andy Miller

--- In motm@yahoogroups.com, Richard Brewster <pugix@...> wrote:
>
> Obvious question: Do the 1V/octave and FM2 inputs work as expected? If
> so, then it's just a problem with the FM1 Exp. If those other
> exponential inputs don't work, the problem is more central.
>
> Richard Brewster
> http://pugix.com
>
> On 11/13/12 12:37 PM, gooboworks wrote:
> > Folks, I just finished building a MOTM 300 VCO. I have a problem. the EXP/LIN switch is not acting correctly. When I have a LFO control voltage in FM1 the oscillator appears to work fine when the switch is in the LIN position. When I switch it to EXP, the oscillator will does not react, the oscillator acts as if nothing is inserted into the FM1 jack.
> >
> > I am an experienced builder and I have built MOTM 300's before. I know I can email Paul S. on this, but I wanted to hit the list first to see if anyone had any tips on where I might look for an issue.
> >
> > Any thoughts on what might be the problem and where I can look?
> >
> > Thanks
> > Andy Miller
> >
> >
> >
> >
>

On Wed, Nov 14, 2012 at 7:18 PM, Paul Schreiber <synth1@...> wrote:

 

All the available MOTM information is located here:

 

http://synthtech.com/motm/docs/

 

Look over the ‘300 Theory of Operation. It’s hard to trouble shoot VCOs without a scope handy.

 

Paul S.