A subtractive analog synth similar in many ways to other CS series, but this one has a duophonic capability. Not sure which method they used. Similar to CS20M in memory design I'm sure.
Typical problems in CS series are power supply over voltages which blow tantalum capacitors and they short, or the caps just fail over the years. During this various chips may be taken out. I've seen LFO chip, VCA's and dac comparator fail so they might be most susceptable. SEE CS20M for more tips since I've never worked on a CS40M and the 20M is very similar. Also fuse resistors may blow in the insulating jackets in PS if fault occurs.
I had a most peculiar manifestation shown in a video I did on CS5. The cutoff control would just cease to impact a highly filtered sound at the Ab second from top and below or like that. It would change a note during warmup. Turned out the VCF chip was the issue!
Slider caps and Knobs- I have a decent selection of rotary knobs The sliders are identical to those used in Moog Opus 3 etc. I have some reproductions from chipforbrains. Not cheap since they're out of production again i think. I try to keep some crude reproduction slider caps in at 6.00 each.(Contact Sound Doctorin')
Semiconductor and Parts:
See Semiconductor page. I believe I should have any electronic part or keys for these save exact transformer, etc. Ask if you have need.
Contact Sound Doctorin'