Hi.
I wonder if either (or both) the Yamaha CS50 or SK20 synths could be midified. I'd only be looking for note on/off. I know the CS50 has a MIDI kit already, but that's very expensive and adds a bunch of features I wouldn't necessarily want.
Service manuals are here:
http://www.cem3374.com/docs/Manuals/Yamaha/CS-50_SM.PDF
https://dl.dropboxusercontent.com/u/4447157/yamaha_sk20_synthesizer_sm.pdf
Thanks.