Vintage Synth Repair

I detected a bad 80017 only by heat, once. The bad chip was so hot 
that it was clear it was the cause for the problem. All voltages main 
were bad too.


--- In vintagesynthrepair@yahoogroups.com, "easterleggs" 
<milotoll@...> wrote:
>
> yes. chip one is suspect.  but see if you can pinpoint which voices
> have the filter cutoff problem.  that problem is likely also
> associated with the 80017's, but you may have more than just chip 
no.
> 1 to replace!  in my experience when one goes, the others aren't far
> behind.  oh, and it's typically wise to wait 15-30 minutes before
> doing these tests so the instrument is performing at normal 
operating
> temperature.  you may even notice one or two of the 80017 chips are
> hot to the touch.  that's not good.  good luck!
> 
> 
> 
> --- In vintagesynthrepair@yahoogroups.com, "sputnik979"
> <sputnik979@> wrote:
> >
> > So I understand that what you're saying is that this is indeed 
the 
> > VCA/VCF chip problem and nothing else?
> > 
> > PS. New info: every couple of notes the filter cutoff is slightly 
lower 
> > than the other notes I strike. But it's not every sixth note. 
It's more 
> > random.
> > 
> > And when in the test mode, the 1st voice (so the LCD shows) is 
the one 
> > that always gets stuck on. And here the problem manifests itself 
> > exactly every six notes. I guess I need to replace 80017a number 
one?
> > 
> > cheers
> > 
> > 
> > --- In vintagesynthrepair@yahoogroups.com, "gil_we" <gil_we@> 
wrote:
> > >
> > > Have you checked all the basic things... i.e correct voltages, 
heated 
> > > parts, etc ?
> > > 
> > > I once fixed a 106 which had a bad VCF/VCA chip. The bad chip 
heated 
> > > as hell !
> >
>