[sdiy] Arp ProSoloist...strange behavior.

[Bob Weigel]

On 4/2/2013 11:38 PM, Jim Blair wrote:
> I just picked up a second ProSoloist (kind of the third, if you count 
> the ProDGX). This one sat in a closet for 40 years, then restored. 
> Perfect condition. Except for one thing....
>
> Both of the "Fuzz Guitar" presets behave oddly. It seems like they 
> sort of "cycle through" slightly different waveforms. Sine, square, 
> saw, etc. Abruptly, almost like someone reciting vowels. also, Fuzz 
> Guitar 1 is kind of quiet, while Fuzz Guitar 2 is really loud.
>
> Everything else is great.
>
>
> Any suggestions?
>
>
>
> Thanks,
>
> Jim
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>
>
Hmm.  Well are the sounds it cycles through affect by other tabs that 
are down?  Eg. if you put all tabs up does it cease cycling?  If so 
maybe the switch is intermittent.  Otherwise, the principle of operation 
is this.  The logic is supposed to only recognize the furthest right 
switch that is engaged.  From that it establishes an address that is fed 
to a series of ROM chips. These chips' outputs then are attached to 
various things.  For example a feedback in an op amp filter circuit 
where if that line is high it allows the function but if low it defeats it.



-- 
Check out sounddoctorin.com for songs, a studio tour, help
repairing old synthesizers and parts or thought provoking
articles that could help make your eternity!