It sounds like that voice card has a broken octave select circuit.
They call it the transposition gating circuit in the service manual. My
offhand guess is one of the FETs went bad (one of FET1 through FET4) on
the affected board and is holding the highest octave selection "on" all
the time. The circuit for the "M" boards of the CS-80 is 99% the same as
that for the CS-50; there are only a few resistor values changed, and a
few omitted parts (the CS-50 does not have the stops for fifths, only
octaves).
As for the touch response, check to make sure the light source (a small
12V or 16V bulb--24V will also work) under the keyboard itself is not
burnt out. It is mounted under the left end of the keyboard keys and is
covered by a pull-off rubber housing. It should be lit whenever the power
is on. Note that the keyboard is on hinges similar to the main lid; just
loosen two screws on the underside of the case and the keyboard will swing
up into a vertical position.
Crow
/∗∗/
On Thu, 5 Aug 2004, zendenker wrote:
> I recently acquired a CS-50. I really love the unique sound of this
> synth and can't wait to record it. It has 2 problems though: the
> touch-sensitivity is not working and one of the voice cards tracks
> the keyboard, but with a pitch about 4 or 5 octaves above the other
> voices-- this voice squeaks instead of squaking.