Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: tubesornothing on October 02, 2021, 09:26:53 pm
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A friend has a tube Amp that has an old 2 prong plug and is causing shocks when touch the chassis, and the person touches ground. I will replace with a 3 prong plugs, but I think the problem is more serious.
When I measure from chassis to ground, 1 get zero volts when powered off. Regardless of the polarity of the ac plug.
When I do the same measurement with it powered on, I get approx 70 volts. One time it showed 350v.
What is my next step in diagnosis of the leaky component?
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Which amp?
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It may not be wrong for an UN-grounded amp to show half the wall voltage. That's what it would drift to if everything were equal.
You could be curious and try a 50k resistor to wall ground. Does the floating voltage change?
However a SOLID ground is best, because if a major leak happens it will blow the cellar fuse.
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Thanks guys, I will try the experiment. This is a jukebox Amp. I will see if I can dig up a schematic.
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...This is a jukebox Amp....
Which amp?