OldSynths

Thanks for the response Crow, it was very helpful.

As it turns out the light under the keyboard was burned out. Also,
I didn't realize just how hard you need to press on the keyboard to
get the touch response to open up, definitely not feather-light
response as in many of todays keyboards. In case it's of interest
to anyone: the lamp is a Toshiba marked A24V5W.

I've found a source for the service manual and it should be in the
mail this week, but I went ahead and ordered a handful 2SK30 FETS to
replace the ones on the ailing voice board. Maybe that'll do it,
and the problem will be fixed even before the service manual gets
here.. Anyway, thanks again. I'll be sure to update for the archive.

> 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.