Thank you for the detailed and fast response. Probably a bit over my head, but perhaps I'll get there someday...
Jesse
Jesse
--- In chromapolaris@yahoogroups.com, "Paul D. DeRocco" <pderocco@...> wrote:
>
> > From: jesseterry
> >
> > Hi, New Chroma Polaris user, and I've got a problem,
> > wondering if any of you have an idea.
> >
> > I get random Pitch bend drift, like the following:
> >
> > 11:53:37.336 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -1408
> > 11:53:37.359 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -1152
> > 11:53:37.696 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -896
> > 11:53:37.718 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -768
> > 11:53:37.730 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -640
> > 11:53:38.099 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -512
> > 11:53:38.258 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -896
> > 11:53:38.437 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -1024
> > 11:53:38.449 From MIDISPORT 2x2 Port B Pitch Wheel
> > 1 -1152
> >
> > I've replaced the pitch bend and modulation pots, with no
> > luck, and tried a different MIDI interface. I've recalibrated
> > the pitch and mod levers with no luck.
> >
> > It seems to go away for a bit if I reset the Polaris, but
> > eventually starts drifting again in spurts if I use the pitch
> > level. I can workaround by setting the Pitch Bend Lever range
> > to zero, but then I miss out on the pedal steel pitch bend fun.
> >
> > Any ideas?
>
> You'll have to trace through the circuit with a meter, always measuring
> relative to the same ground, preferably near the A/D converter on the
> main board. The levers get their power from analog +12V on the panel
> board, so see if that moves concurrently with your pitch wheel MIDI
> output changing. The signals then go down to the main board, where
> they're converted to digital using a reference derived from analog +5V,
> so see if that moves. The reference is divided down from +5V with a
> trimpot (R45), so see if the output of that is stable. It could also be
> bad op-amps along the way, bad 4051 multiplexers, or even a bad A/D
> converter (Z53).
>
> --
>
> Ciao, Paul D. DeRocco
> Paul mailto:pderocco@...
>