Circuit Overview:
Korg's first ROM based waveform synth; a hybrid with 6 analog filters. These use three potted modules that are fed CV's from 4051's and have op amp buffered outs that feed the vcf log pins. I'm not sure what these do. Anyone? A clever bit of digital domain harmonic manipulation is used to generate the 8 waveforms though to a DAC-08 and then to the NJM2069 vcf/vca chips. The sound is similar to the Kawai K3 in many ways it seems programming it. I suppose the waveform technology is pretty similar.
Service Tips:
Typical problems with contacts in the Panasonic type keyboard I suppose though the one I worked on was fine recently. Haven't heard of any other particular weaknesses.
Parts:
I believe you'll draw mostly blank looks from Korg on these units. I have some parts that are the same so feel free to ask what the current stock is on a given thing. VCF Chips I could scrap from a DSS-1 board, and most of the smaller digital chips of course but there are several things like the wave rom and ROHM modules that would only be available from a scrap unit I'd think.