[sdiy] seek help on Jupiter 6 repair

[Eduardo]

hmm,  I don't know what that IC 20 is about, but if these are the osc
outputs you are measuring,

I'd follow the 100hz signal back to the oscillator that is generating it and
take the circuitboard out and make sure that any surface mounted parts on
the bottom have not come off the CEM chip. or one of the leads is not bent
and touching another part.  my problem was that one oscillator was 3 octaves
too high than all the others.  I am not sure if it your problem, but it
might be it.

maybe double check the osc outputs at the voiceboards themselves.

hope that helps something.

Good luck

Ed
----- Original Message -----
From: "Anderson, Robert O" <RobertOAnderson at eaton.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Wednesday, September 18, 2002 9:33 AM
Subject: RE: [sdiy] seek help on Jupiter 6 repair


> >From: J. Larry Hendry [mailto:jlarryh at iquest.net]
> >Here are the scans of the earlier versions of the voice boards.
Hopefully
>
> Thanks everybody, I've hooked up the scope to IC20 4051 mux looking at
each
> oscillator output.  All twelve appear to have a heatbeat..  The
frequencies
> of nine of them are only about 1 Hz.  A couple are less than 1 Hz.  And
one
> is about 100Hz.  I guess the tuning procedure first does a low freq then
> high freq calibration and I'm stuck on the low one.
> Anyone know the passable freq spec?  I should try splitting the TX from
two
> voice boards to see if only one board has a high TX.  TX goes to plug
MC4:7.
>
>
> I'll also investigate the sample and holds.  Looks like the CEM3340 gets
the
> sum of FREQ+CV+Bend.  If the Bend voltage was off it could ruin the tune
> procedure.
> Bob A