Roland M-SE1

[dmeek]

Synth sound module, one of the "Sound Expansion" series. Got it for free, has no output. Looking for a schematic.

[Jazz P Bass]

No Gots.
This page does explain how it works.
https://www.polynominal.com/roland-mvs1/

[dmeek]

Got it working. It was a case of: If nothing else works, read the owners manual. A new battery and Factory Reset fixed it. This thing has every variation of string section known to Man.