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Subject: Re: touch sensitivity irregularity

From: "wasteking1" <wasteking1@...>
Date: 2009-11-23

good news---i got my voice 6 to operate normally again ultimately by just doing a 'tune all' ... i have NO idea what happenned, but im glad its back all i knew was that NO chips were bad . anyhow, i still have no idea what controls the touch sensitivity on each voice. it does NOT appear to be the 4 socketed chips in the sample hold area. but that problem is minimal compared to loosing a whole voice.

--- In chromapolaris@yahoogroups.com, "wasteking1" <wasteking1@...> wrote:
>
>
>
> --- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@> wrote:
> >
> > > From: wasteking1
> > >
> > > you were right--i was testing with the master volume slider--- using the
> > > assignable volume it cuts out at about 40% of the way up . At the risk of
> > > sounding even more stupid-- i was wondering how i would check for negative
> > > voltage --crossing pin 7 with what? ground? and my simple anaolg needle
> > > radioshak meter showed +3 volts when i crossed from the battery
> > > to pin 7 on all zx03 chips. [ but i could try swapping Zxo3
> > > chips if they are the likely source] ..i assume
> > > that voices 1-6 correspond to chips numbered z2o3-z703 in the 'X'
> > > place . of
> > > course that places chip Z203 under the output board requiring
> > > unscrewing the
> > > whole main circuitboard.
> >
> > To measure negative voltages with an analog meter, just connect the positive
> > input to the meter to ground somewhere, and use the negative input to probe
> > the op-amp outputs; the negative voltages will show up as positive values on
> > the meter. If you have a digital meter, then it'll have a minus sign.
> >
> > If the chips are socketed, then, yes, swapping them is a good way to find
> > bad chips. It's unlikely to be the capacitors, because leaky capacitors pull
> > the voltage toward ground, not toward the minus rail.
> >
> > --
> >
> > Ciao, Paul D. DeRocco
> > Paul mailto:pderocco@
> >
> well i made a mess now
> i first tried swapping all 5 chips (01.02,03,04,05) in the sample and hold area betwwen the Z2 (voice 1) and Z6 (voice 5)-- no change in the touch sensitivity problem. so i had this great fear that the voices were inverted and maybe voice 1 was actually the Z7 row(actually voice 6)...so i pulled out a chip to see if voice 6 would or wouldnt work-- it didnt sound so i put the chip back having confirmed that it was indeed voice 6... but now voice 6 is all messed up-- it plays only a click on all keys till the c sharp in the 4th octave then itplays a loud tone (but not the patch) then above this i get just a quiet high pitch tone on all notes above. I tried switching ALL chips between voice 5 and 6 but no change -- i seem to have killed voice 6 and still have the problem with voice 1-- any great ideas here??
>