Circuit Overview:
The first computer controllable keyboard via the 'chroma interface' which worked with Apple II's. 16 voice analog signal path with digital control/entry. (To clarify this unit has real VCO's, VCF's, VCA's, EG's. But digital controls. I just realized how that looked and clarified it). It has 8 'dual channel boards' and can be used as 1 VCO/voice 16 voice or 8 voice 2vco/voice. They are a joy to play.
THere seems to be a lot of misinformation floating around about this synth. The article at analog synth gallery whose owner cannot be contacted...seems to contain about every element of the misinformation. Apparently someone said in a keyboard magazine interview that Dodds said they had helped test the 80186 in cooperation with Intel with this machine. Well...maybe they did. But according to Intel the chip was not even available until Feb. 1982 and the Chroma came out when?? 1981. Well things moved slower back then. So very possibly that is correct. It certainly makes no sense that they would have helped troubleshoot a chip that had already been out for several years (oops..remembering that there *was* still a bug of glaring nature on the 286...hehe..or does it?). BUT IF SO the likely source of confusion here is that it was presumed by Keyboard magazine that the unit actually USED the chip because of the statement that they had worked with intel to *test* a prototype chip that was not even available yet. So, I'm fairly convinced that this mystery is solved.
Furthermore there is an error re: the voicing structure on the page making it appear that it has 32VCO's as I read the grammar. People hear it's 16voice and that it can have 2osc/voice and they don't realize that there are only 16 total vco's there.
Service Tips:
Again mass resources on RC page. Power supply was weak. I did a lot of work on one and expander in CT and there was a wide variety of troubles on the voice cards. Mostly bad op amps as I recall. We dodged getting a filter chip which initially appeared a problem. Some iffy interconnects and solder.
Parts:
For general electronic parts I can probably supply but others are no doubt hard to find.
Contact Sound Doctorin'