Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Crispy on June 05, 2015, 07:12:20 am
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Finishing up my first build, a scratch build using Doug's 5f2a circuit (and board, small parts etc.) When I power it off, by the time I get my meter connected, I'm down to 20 V DC or less. Looking at the schematic, every path to ground that I see, has either a polarized capacitor or a vacuum inside a tube between B+ and ground. Is there a "leak-down" resistor or something I'm not seeing, or do I have 1 or more bad filter caps, or what?
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Not enough information. If you installed a bleeder or leak down resistor it still should have more voltage on it unless it takes you 20 seconds to clip your leads.
Does the amp work or have you not gotten that far yet.
I'll bet if you measure your unloaded voltages (tubes out) and take some high res photos and sample the photos down to 1200 pix and post them you can get some help quickly.
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That's normal. The tubes will continue to conduct until the filament cools enough to shut off current flow. Since the caps are no longer being charged the voltage will be drained due to the still conducting tubes.
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Thanks, Sluckey! Yes, the amp works, though I'm still fine-tuning it. I used Classic Tone Transformers (15W OT) and I'm swapping the 6v6 for a 6L6 for more headroom, also changed speakers and now I have to move the tubes over 1 socket hole for clearance (glad I drilled that extra hole!) This has just been bugging me the whole times, but I ran into so many other problems ( bad speaker, cracked tube socket) that this one seemed relatively minor. Peace out!
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Sorry, I assumed you were not up and running yet. I guess I should keep my mouth. :sad2:
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No problem, Ed. Just glad I've got one less thing to worry about, now!