[sdiy] Prophet 5 P-Mod Filter Envelope turning problem

[Gil W.]

Thanks, replacing these two chips didn't make any change...



--- On Tue, 4/12/11, klosmon <klosmon at sbcglobal.net> wrote:

> From: klosmon <klosmon at sbcglobal.net>
> Subject: Re: [sdiy] Prophet 5 P-Mod Filter Envelope turning problem
> To: "Gil W." <gil_we at yahoo.com>, "synth" <synth-diy at dropmix.xs4all.nl>
> Date: Tuesday, April 12, 2011, 5:35 AM
> Hola Gil --
> If we're talking about a rev3, check the voltages at the
> input & output 
> of the polymod buffer IC (U431 for voice 1), and the
> polymod switch IC 
> (U459) -- either one could be bad.
> 
> ~GMM
> 
> 
> Gil W. wrote:
> > Can anyone help with this please ?
> >
> > Under the Poly Mod section, if I turn the Filter
> Envelope knob all way down,
> > and engage the Destination Freq A switch (on), start
> playing, the first note (osc 1) pitch is way up in relation
> to the note played. When the rest 4 oscillators are played,
> there is no different in pitch whenever the Freq A switch is
> engaged or not (same pitch when switch is either On or Off).
> Only for the first oscillator, if I switch the Freq A button
> On, pitch will raise...
> >
> > I tried to fiddle with each of the trimpots in the
> poly mod section but non of them controls the pitch. Also
> switched VCA chips in the P-Mod section between osc1 and
> osc4, the problem in osc1 remains and osc4 works ok with the
> CA chips switched...
> >
> > any suggestion where the problem can lay ?
> >
> > Thanks a lot for the help !
> >
> >
> >       
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> >
> >   
> 
>