Hi, Thanks for the thought on the patent idea. Maybe. I checked on the other link and no schematic. Not in "Riders" either nor at the company web site. It isn't even listed as one they made. I'm guessing it was a really low production thing and eveyone has forgotten about it. I have started to map out the active part of the circuit. The PS is fully encapsulated in a type of plastic, probably like bakelite and is inside a metal case that is welded to the chassis. It is not likely to be functional and I would not trust it anyhow. The restoration will be somewhat more modern and eliminate a potential shock hazard as one side of the headphones goes to the sub chassis via a 10K resistor. The sub chassis is connected to the AC mains even though there is a power trannie in use. I guess they didn't see that as a hazard if the resistor failed. I have seen some designs like it that routed the B+ through the headphones as well. Ugh!
Still searching
Good listening
Bruce