Quote:
Originally Posted by Don Lindsly
That is a "hot" chassis. One side is connected to the AC.
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A brief look at the tube line up made it look like a transformer powered set, and I thought I saw a power transformer in there. But I don't see a rectifier tube in the list. Must be only a "filament" (heater) transformer and otherwise a hot chassis. Probably a selenium rectifier (maybe a doubler circuit) in there. I've seen sets that have the chassis at voltage either way the plug is plugged in, chassis tied to a negative rectifier output, and B+ tied to a positive output of a 2nd rectifier. Similar to how a modern PC power supply, set to 120V mode, does it on its input (line) side. And modern SS sets usually have a bridge rectifier, so the chassis ground looks to always have about 80VAC on it. Isolation transformers would be a must. One that can do around 250W should be what you'd need.