[sdiy] prophet 600 -- tough problem

[greg montalbano]

At 07:13 PM 6/4/02 -0400, Andrew wrote:

>  Hi,
>  If I may ask...what are the symptoms with your Prophet 600? Will it play at
>all?  I have problems with mine sometimes when using lots of pitch bend, mod
>wheel or playing fast solos. Sometimes notes will get lost and sometimes
>notes will "hang". I've noticed latency with the note-ons too.

Nope -- my problem is with six specific control voltages;  everything else 
works just fine.


>  I just got through doing a recording using the P600 and had to restrict use
>of the performance controllers because of these problems. The setup I was
>using was P600 MIDI out ->Encore Expressionist -> MOTM modular, but I've
>noticed it while playing just the P600 alone. I have the latest OS installed
>(6.08).
>
>  Has anyone else run into this problem with their Prophet 600s?
>
>  Thanks,
>   Andrew
>
>
> > From: "greg montalbano" <greg.montalbano at ucop.edu>
> >  To: <synth-diy at dropmix.xs4all.nl>
> >  Sent: Tuesday, June 04, 2002 3:46 PM
> >  Subject: [sdiy] prophet 600 -- tough problem
> >
> >
> >  > Hi--
> >  > I'm hoping to hear from anyone who has specific, detailed knowledge of
>the
> >  > workings of the digital portion of this synth.
> >  > I have several control voltages that are completely screwed;  but the
> >  > problem is definitely upstream from the four 4051 demultiplexers*.
> >  Looking
> >  > at the outputs of those four ICs in order (on schematic "Board 4, page 1
> >  of
> >  > 4"), the bad CVs form a pattern: 00X00XOO XOOXOOXO etc etc, where O= a
> >  good
> >  > CV and X= a bad one.  This leads me to suspect a problem with the 
> data or
> >  > address lines controlling the DAC and/or demultiplexers;  can anyone 
> tell
> >  > me exactly what to look for and where to look?
> >  > Everything else on the synth is functioning correctly & consistently.
> >  >
> >  > Thanks.
> >  >
> >  > ~GMM