CS-30 (or other CS-Mono) circuit detail ?

Haible_Juergen#Tel2743 HJ2743 at denbgm3xm.scnn1.msmgate.m30x.nbg.scn.de
Mon Oct 28 22:16:00 CET 1996


Received my CS-50 service manual this weekend.
Now I want to build a monophonic / 4VCO and
douphonic / 2VCO mode into this synth.
Question is, how do I tell the key assigner IC not to
put out 4 notes, but only 2 or 1 instead ?
The manual says that I have to connect unused
outputs 5 ... 8 and a strange 9th "mode" pin
to the opposite supply rail to switch between
4-note (CS-50) and 8-note (CS-60/80) polyphony.
Now it doesn't take much to guess that I might
get duophonic and monophonic mode if I do the
same thing on outputs 2 ...4. But I want to be really
sure before I touch this part, so I'd ask someone
who has the manual for a monophonic CS-synth
if my theory fits or not.
Do the CS-30, CS-15 etc. also use a 40-pin custom
chip for keyboard scanning?
How are the pins 34 ... 40 connected? (should be
22k resistors that go to two different rails ...)
Could anybody confirm this, or tell me if it's completely
Caution! It might be *wrong* in the *overall* schematic
diagram! (It's wrong in the CS-50 overall diag, but it's
right in the detail diagram of the keyboard logic, and
in the pcb component overlay diagram.)

Thanks in advance for any piece of information,


More information about the Synth-diy mailing list