Circuit Overview:
Novachord is a massive circuit with 163 tubes I read. But we are talking just networks of resistors and capacitors and vacuum tubes here pretty much. The solovox uses a huge inductor for tuning and assume these probably have the same. The solovox I have and have worked on and it's a monophonic version with far fewer parameters. I can imagine these are one of the most wonderful instruments ever made in many ways. They are a beast though. Oldtech site has a nice bit of information.
Service Tips:
Clean tube sockets, check tubes, replace a lot of capacitors and resistors probably to get these up to spec.
Parts:
Lots of discrete parts but likely some oddball ones. Ask if you need a specific part.
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