Analog subtractive with digital control galore. 12DCO 6 voice. Identical to the Matrix 12 in a half voiced desktop version. This matrix 12 page here has a lot of good information; things you may want to know before attempting to troubleshoot these.
Troubleshooting should be similar to a lot of other analogs with digital control but..a lot more of it to deal with. I strongly recommend nobody who isn't quite experienced try to work on these synths in general. Not a piece to learn on. :-) The DAC chips have been known to be a problem and are not available commonly unfortunately. See alphaentek for a great page on this synth and other Oberheims.
NOTE: Regarding CEM3372 VCF's. We had a recent bit of experience trying to get these to work in Doug Terrebone's Prophet 600 and in one I had here. None of the stock I had would sound the same (not to mention that two I got from chipforbrains some time back were totally doa... bummer. Thought those were NOS!) They lacked the whispy overtones with Resonance all the way up in particular. THey were all "C" revision. The "B" rev's were in the P600's but Doug said he finally got in an AX80 that had Rev "C's" and those worked fine! Go figure! Anyway just beware that there is some variation in these chips.
You might find these people helpful who bought parts when Gibson offloaded them:
Phone: 760 246-3866
Fax: 760 246-3494
or 800 603-5427 if it still works (I checked..none of these are good anymore. Will update if I get some that are.)
Contact Sound Doctorin' if you need something I might have.