[sdiy] help me with a Moog Source, please

[Peter Blackett]

Hi Sergio and list.
It has been a long time since i looked at one, but I think that you 
should check the smoothing caps around the sample and hold circuits, as 
I seem to remember that if one of these went open curcuit then this 
would give some strange  results. it could also be a problem with the  
4051 multiplexers as well.
I think the other comments about the power supply are well founded........
regards Peter

> Hi to the list...
>
> I'm getting very nervous with a Moog Source, and I need to know
> if anyone has experimented the same problem.
>
> The VCA's envelope seems to affect the pitch of both VCOs, and
> there are no way to avoid it.
> With the oscilloscope, I have found a saw waveform mounted on
> the CV (after the 4051 demultiplexers) and its amplitude varies
> with the VCA envelope levels. In fact, if I change the sustain level
> it affects the VCOs like a pitch bend.
>
> Curiosly, that "interference saw" not produces an audio frequency
> modulation on VCOs, as would be logical.
>
> I have tryed everything, and I'm really desperate.
>
> If anyone of you has experimented something similar, please, tell me
> how you solved it.
>
> Thanks in advance.
>
> Sergio
>
>
>