Circuit Overview:
A fairly basic analog synth with memory and bbd chorus/ensemble/phaser. Knobs track from current memory location rather than knob location which I always prefer in performance. One of the few polysynths in the affordable range that has full analog signal path and analog EG's. Arpeggiator.
Service Tips:
Have seen problems with Chorus boards and also failure in LM13600 dual ota chips. My own unit however had the peculiar symptom of having noise instead of oscillators it seemed. Since..there is no noise source by design this was a little puzzling. Turns out though that the 4066 chips which turn on/off the signal flow from the various oscillator sources (ie. pulse, saw) were receiving a bizarre signal from the 4042 latches. Another unit had lights on all the time like 2,3 and b,c. These problems are typical of what happens when lines get dissolved by the battery acid. They often APPEAR to still have copper in them..but can be totally non-conductive oxides in place. You simply have to Cut out the 74LS08 near the battery and before replacing it totally check every connection and trace in that vicinity.See helpful tips on Old Crow's site. Or see my advice in poly-61 section for service tips if that doesn't work.
Parts:
I believe you'll draw mostly blank looks from Korg on these units. I have some parts so feel free to ask what the current stock is on a given thing. Some of the less common parts are getting quite hard to find though. I have SSM2044's for instance and 2056's. Occasionally parts are on ebay also.