Vintage Synth Repair

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 !
>