From here I turned my attention to the schematic found
here.
And the tube location chart found
here.
After examining a number of other schematics from other early 21 inch color sets, it looks to me to have the "RCA Licensee" circuit, but with the high voltage section more closely resembling that of the 21-CT-55, and a few tube types changed. Perhaps Hoffman received an excellent deal on the 6K6 used as the audio output, and opted to use that instead of the 6AQ5 used by other manufacturers. In any case, if anyone has a copy of RCA Licensee Bulletin No. 962 (dated September 16th of 1954), I'd love to see it. I'm curious as to what exactly RCA specified in that circuit, and where Hoffman deviated from that.
For comparison sake, the
schematic of the Sentinel IU-816 bears some very striking similarities, especially in the IF strip and color circuits.
Any info on the RCA licensee circuit would be greatly appreciated.
I guess this is it for the time being. I have an ongoing, perplexing medical issue that will very likely leave me hospitalized for some time. I hope to be back home and digging into the set by Christmas, but I'm not holding my breath...
- Ben