The Kawai & Teisco Analog Synths Group

I'm not sure if it's on all the voices; I'll check in the next few 
days.  You're probably right, Gil, about the op amp.  AND the need 
for a schematic.  If I can't find one, I guess I'll just make a list 
of all the ICs on the synth board, google the datasheets, and 
play 'hunt & peck' with the scope.  Luckily, I'm not seriously 
hobbled without it.  I'm really glad that I don't have to depend on a 
bunch of old, cobbled together gear to gig with, like the old days...

--- In kawai-teisco@yahoogroups.com, "gil_we" <gil_we@...> wrote:
>
> 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'.
> >
>