In Reply to: RE: Also.... posted by Nickel Core on October 24, 2014 at 00:39:04:
10A B+?? Holy moley! Well, it sounds like whatever was output from the pre when you switched it off was high enough amplitude and duration to push the grid of the 300B positive. Wow, I never would have imagined a B+ supply could burn out a DHT filament. If this is heated with a CT filament transformer, you might consider installing a small fuse in the connection between the CT and ground (or between the hum pot/cathode resistor and ground). I would also scope the output of the pre when its connected to the amplifier to see if it's oscillating during power-down.
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Follow Ups
- RE: Also.... - Triode_Kingdom 08:42:54 10/24/14 (0)