Sick Cheetah

[Charlie T]

I was really surprised at the interest and feedback I got regarding my ailing Cheetah master controller.  Paul Schreiber has kindly agreed to take a look at it, I'm in Houston and he's in Fort Worth so it works out great.  However, since several list members asked for details, I'll cut and paste from my letter to Paul describing the very odd symptoms.

The problem with the unit is extremely strange.  When I play certain notes,
ONLY in combination with certain other notes, they begin to trigger,
rapid-fire.  It almost sounds as though an arpeggiator  is running, but only
on those notes.  In all of the examples below, I'm talking about playing a
major chord, with both hands, beginning on the root, and covering two
octaves, with all elements of the chord present.  For instance, the first
chord would be the third B below Middle C, then the d# immediately above
that, then the F#, B, D#, F#, and on top, the B directly below Middle C.
This is just by way of example, there are other combinations that cause the
problem, and I'm sure I haven't exhausted the possibilities of combinations
that MAY cause it.

But for the purposes of explaining the problem when I play the two fisted
triad described above beginning on

3rd B below middle C - most of the notes multiple trigger
2nd Ab below m C - Eb below m C mult trigs
Eb below m C - G above mC mult trigs, top Eb does too, but at slower rate
B below mC - the highest D# mult trigs, highest B does too, but at a slower
rate

the lowest Eb on the keyboard - almost all notes retrigger

Note that there is always a D# or Eb involved.  If I understand the little
bit that I know about keyboard design properly, if octave division is
involved, shouldn't this be a clue?  It seems and awfully strange
coincidence, otherwise.

You should also know that when I spread out a chord for a more open voicing,
I still have the problem, but again, only in chords where an Eb (D#) is
involved..........

Another part of the whole weird mess, and this only one example:  If I play
a B major triad below mid C, and the notes are retriggering themselves, and
I hold that chord down with my left hand, then play the same chord a couple
of octaves up with my right, the problem will stop, UNTIL I LIFT UP MY RIGHT
HAND, when it begins again.

Needless to say, it renders the keyboard worthless.

What I've already done:

Completely isolated the Cheetah from the rest of my rig
(midi patchbays, multiple modules, even used a different AC outlet and
physical location)
Used different modules for testing
Used only the MIDI out port #1
Used different MIDI cables
Verified with a sequencer that the keyboard is, indeed, sending multiple
notes on
Cold booted

So I think the above notes are well researched; I don't think I can blame
the problem on anything but the Cheetah itself.
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