Yamaha CS-5

Manual PDF & http://www.fantasyjackpalance.com
schematics: CS-10 schematics and service manual. They should be pretty similiar to the CS-5. 
mods http://www.yamahasynth.com/classic/older/d_cs5mod.htm

• Specifications
• Polyphony - Monophonic
• Oscillators - 1 VCO with pulse or sawtooth waveforms and noise-gen
• LFO - Yes, with sine, sawtooth, sample and hold
• Filter - 1 filter: 12dB/oct High pass or Low pass; 6dB/oct band-pass
• Effects - None
• Keyboard - 37 keys
• Memory - None
• Control - CV / Gate
• Date Produced - 1979-83