A synth somewhat similar to the PolySix but with digital oscillators. Typical subtractive analog architecture with memory. The Midi version is Korg's first Midi synth. I have a non-M version that has MIDI ports also.
Problems with the keyboards are common. The 'conductive impregnated rubber' key contacts tend to get 'dulled'. I and others have had some success rubbing them with acetone. This apprently can cause the surface of the rubber to break down some and peel off with abrasion and reveal a fresh surface that has conductive material exposed. This is my theory after many operations on these and many successful ventures. I have seen cases where it just won't work though. Not sure why. I'm working on another solution though :). ALSO CHECK THIS AWESOME SITE! Poly-61 Repair at mik-music.org has done a fabulous job of detailing the poly-61 repair procedures! Also here is the Poly-61M MIDI board checklist and troubleshooting guide (KLM-605)
In recent days I've seen some battery spills. One ate a trace completely and required extensive cleanup with alcohol to get the board back in shape. All digital stuff seems to work well from the panel but I can't get a sound out of them. Not time to find out why at the moment.
I believe you'll draw mostly blank looks from Korg on these units. I have scrap units in stock so just ask. Contact