Some of you probably know me (by name if not by reputation), others
might be seeing me for the first time. My name is Scott Rider, aka the
Old Crow. I've been doing synthesizer design and repair work for many
years, with a particular emphasis on the Yamaha CS line, as well as some
of their digital instruments.
I maintain the website where I try to explain in
relatively simple terms what is involved in opening, inspecting and
repairing CS-80 problems. In recent years, however, I've been
concentrating on how to construct the equivalent circuits of various
Yamaha custon ICs, with the goal of making circuit boards useful for
CS-50/60/80 repairs that work and sound like the originals, just without
the problems of trying to track down the getting-harder-to-find parts.
Thus far I have been able to create the "standard parts" equivalents to
the envelope generators, filters and VCA chips. I am currently working on
the VCO (I have a working prototype the reproduces the 'flawed sawtooth'
exactly). I've also made replacement SH and TKC boards. Designed but not
yet boarded is a new KAS (key assigner) designed to replace the original
KAS, and add a few features such as integral MIDI.
Finally, thinking of it to be of some interest, I have also been
breaking open the epoxy-potted NE submodule series as used in the GX-1
(and [C]SY-1, [C]SY-2) in order to re-create those voice elements. Thus
far I have the highpass, bandpass and lowpass filters figured out. The
NE11000 VCO module is next. Some info available here:
Regards,
Crow
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