In Reply to: Fisher X100b schematic wanted posted by psygoat on August 23, 2004 at 06:07:43:
Actually that's a "standard" Fisher trick. The 7868's generate 42v at the cathode, perfect to run a string of 4 x 12v tubes. The tubes see about 10.5v each across the filament, enough to run nicely. Essentially a "free" source of nicely filtered DC.Also the preamp tubes don't see filament voltage until the 7868's have warmed up - probably a nice slow turn-on feature.
I have the service manual, and can send it as a 395K PDF file or via mail. Contact me privately for a copy.
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Follow Ups
- Re: Fisher X100b schematic wanted - Gary Kaufman 08/23/0409:27:40 08/23/04 (0)