OldSynths

Hi Ed,

Are you suggesting that the keyboard scanning chips might be the culprit?  Sending 
no note/octave information?  Or do you mean that no voltage *at all* is reaching the 
oscillator?

Thanks,
David

--- In oldsynths@yahoogroups.com, Ed Edelenbos <eded@s...> wrote:
> Sounds to me like the V into the osc. isn't making it...  
> 
> Ed
> 
> David Shoemaker wrote:
> 
> > Hi everyone,
> >
> > I took delivery on my ARP Pro Soloist today.  I knew it would need
> > repairs when I bought it, and here's what I've discovered so far.  I
> > would really appreciate any suggestions on the next diagnostic/repair
> > steps.  I have a hunch this is not going to be that complicated. 
> > (crossing fingers)
> >
> > Here's the problem:  It powers up correctly.  Every key triggers a
> > sound, but the pitch does not change from key to key.  The sound it
> > *does* make is a very low cycle tone, much lower than any keyboard
> > should make.  It does not seem to be an LFO, because:  The pitch
> > changes in octaves (roughly) as I move the octave shift lever.   Of
> > course, the pitch is so low to start with that the "normal" and "low"
> > octave settings are just clicks.  The pitch does NOT change, as far as
> > I can tell, when I adjust the tuning trimpot, nor does it respond to
> > the front panel tune "knob".
> >
> > The preset switches DO change the timbre of the sound, as if the
> > filters are working correctly.  The volume slider works normally.  The
> > "touch sensitivity" switches act as they should EXCEPT for the pitch
> > bend, and possibly the vibrato (hard to tell with such a low pitch
> > though).  Portamento does NOT seem to work.
> >
> > The presets I would expect to be in a lower octave seem to be so, e.g.
> > "Bass", "Tuba".
> >
> > What I've done so far:
> >
> > --I replaced the aluminum caps in the power supply, and the output from
> > the power supply is normal.
> > --I very carefully cleaned all the oxidation off the J-wires and the
> > contact bar.  Key triggering is almost perfect as far as I can tell.
> >
> > Can anyone offer any suggestions?  I have a couple sources for spare
> > parts if I need them--I'm just not sure what to test/fix next.
> >
> > Thanks very much,
> > David Shoemaker
> >
> >