Vintage Synth Repair

Since all the other keys work, I would suspect the problem is the key it's self.
Does the ProDGX use a resistor or diode keyboard?
Either way, check for a bad resistor/diode on the suspect key, also look for cracked solder joints, or possibly a short to the gate or after-touch buss.

On a side note, do you live on Vancouver Island?

Dave

--- In vintagesynthrepair@yahoogroups.com, Jim Blair <ceratos@...> wrote:
>
> Thanks for your reply, DT.
> 
> No sample and hold on the ProDGX.
> 
> The note does not stay at the correct frequency 
> when held. The pitch drop happens immediately on "note on".
> 
> J wires are aligned, and cleaned, as is the bar.
> 
> 
> Jim
> 
> 
> At 05:34 AM 12/17/2012, you wrote:
> >
> >
> >Hi Jim,
> >
> >The fact that the rest of the keyboard works 
> >fine seems to rule out that the sample hold 
> >function is awry. Does the note stay at the 
> >correct frequency if you hold it down? Is it 
> >only pitch dropping on the release? Have you 
> >checked to make sure the Jwires are aligned 
> >properly on that key? Maybe open it up and check 
> >to ensure that the contact wires on that top key 
> >are aligned the same way as for all the others. 
> >If not, bend them back carefully to match the others.
> >
> >(but I'm not really a tech, so don't just listen to me).
> >
> >best DT
> >
> >--- In 
> ><mailto:vintagesynthrepair%40yahoogroups.com>vintagesynthrepair@yahoogroups.com, 
> >Jim Blair <ceratos@> wrote:
> > >
> > > Hello!
> > >
> > > Here's an odd one up for discussion. I have a Arp ProDGX. Everything
> > > works fine....except.....if I hit the top key (highest note) it
> > > briefly plays the note, then very quickly drops down to a much lower
> > > note (almost instantaneously). After this little event, every key
> > > stops working, other than a click for each note.
> > >
> > > This happens on every patch.
> > >
> > > Then, if I turn the power off, then back on, everything is fine again
> > > until the next time I hit that highest note.
> > >
> > > Any suggestions on where to point my screwdriver and multimeter?
> > >
> > >
> > > Thanks,
> > >
> > > Jim Blair
> > > Ape Island Sound
> > > 
> > <http://www.facebook.com/ApeIslandSound>http://www.facebook.com/ApeIslandSound
> > >
> >
> >
> >
> >No virus found in this message.
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>