The Kawai & Teisco Analog Synths Group

My bet is that there's a bad opamp, or another 4xxx chip in the Cutoff
circuit... Does it happen on all voices ?

I had two bad 4066 in mine, so you might want to check in that
direction. But again, I think you'll need the schematics.








--- In kawai-teisco@yahoogroups.com, "jfloydhumanoid"
<capstoneliving@...> wrote:
>
> --- In kawai-teisco@yahoogroups.com, "gil_we" <gil_we@> wrote:
> >
> > Can you describe the problem more precisely ?
> > 
> > 
> > 
> > --- In kawai-teisco@yahoogroups.com, "jfloydhumanoid"
> > <capstoneliving@> wrote:
> > >
> > > --- In kawai-teisco@yahoogroups.com, "gil_we" <gil_we@> wrote:
> > > >
> > > > We're still looking for one. The only scans that I managed to 
> get 
> > > was
> > > > of the main CPU board... (in the Files section)
> > > > 
> > > > 
> > > > 
> > > > --- In kawai-teisco@yahoogroups.com, "jfloydhumanoid"
> > > > <capstoneliving@> wrote:
> > > > >
> > > > > I bought it new in '84, gigged with it a few years, got 
> married, 
> > > & just 
> > > > > dug it out of storage a few months ago.  Of course the patch 
> > > memory was 
> > > > > gone, but amazingly the Ni-Cd battery hadn't leaked.  I 
> replaced 
> > > it, 
> > > > > loaded the factory patches, & it fired right up!  It's in 
> great 
> > > shape, 
> > > > > except for a sort of 'garbled' artifact in sounds with the 
> filter 
> > > > > somewhat stopped down.  If the filter cutoff is all the way 
> open, 
> > > it's 
> > > > > not present.  Anybody have a PDF (or other form) of the 
> service 
> > > > > manual?  I'd be happy to send $ for your trouble...
> > > > >
> > > >
> > > Thanks for looking, Gil...  Anybody have any suggestions where I 
> > > could point my scope probe & discover the origin of this 
> > > unwanted 'distortion'?  I'm not afraid to troubleshoot without a 
> > > schematic...you can't be timid & repair 'vintage' electronics.
> > > - J -
> > >
> >
> It sounds similar to the 'overdriven' sound of a tube amplifier 
> stage, but 'garbled', and not clipped.  When the filter is completely 
> open, the artifact isn't audible; only when the filter cutoff freq is 
> low enough for the heavily 'filtered' sounds.  It also has an aspect 
> of being periodic (having a set, repetitive pattern), suggestive of 
> possibly being a result of some other signal bleeding through, but 
> that's purely speculative...
> In the next few days, if it's possible (and allowed) I'll post an MP3 
> in the files section.  Would that be proper protol in this group?  I 
> don't have much experience in this area, so please forgive me if 
> it 'isn't done'.
>