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Junior Varsity
New and Shocking!
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<blockquote data-quote="TJ Cornish" data-source="post: 16158" data-attributes="member: 162"><p>Re: New and Shocking!</p><p></p><p>MOVs are a likely culprit. In addition to your good tests, I would meter from the grille of your SM58 to the ground of the outlet the amp was plugged into.</p><p></p><p></p><p></p><p>Old amps can have a couple issues - polarity being one, ''death caps'' being another. I played a vintage Hammond a while back and demanded a wireless mic to sing through once I discovered the chassis of the Hammond was at 60 volts to the mic. That's definitely enough to feel. Maybe Bob L or someone that knows more about guitar amps can elaborate.</p><p></p><p></p><p></p><p>By the way - you're probably not going to get a lot of readings that are a 0 volts. You get 0 volts inside the main service entrance between ground and neutral, because they are one and the same at this point. The farther you travel from that point, the more voltage difference there will be. As current on a circuit increases, the voltage between neutral and ground will rise, because the neutral return path has a non-zero resistance, and therefore there is a voltage drop.</p><p></p><p></p><p></p><p>A couple of volts between ground and neutral on a moderately to heavily loaded circuit isn't likely an indication of a problem. If it's more than a few volts, it's wise to try to shut power off and re-torque things.</p><p></p><p></p><p></p><p>Neutral to ground voltages are a separate issue to the shocking phenomena - or at least it better be. Absolutely NOTHING connected to either the neutral or hot wires should be exposed out of a device.</p></blockquote><p></p>
[QUOTE="TJ Cornish, post: 16158, member: 162"] Re: New and Shocking! MOVs are a likely culprit. In addition to your good tests, I would meter from the grille of your SM58 to the ground of the outlet the amp was plugged into. Old amps can have a couple issues - polarity being one, ''death caps'' being another. I played a vintage Hammond a while back and demanded a wireless mic to sing through once I discovered the chassis of the Hammond was at 60 volts to the mic. That's definitely enough to feel. Maybe Bob L or someone that knows more about guitar amps can elaborate. By the way - you're probably not going to get a lot of readings that are a 0 volts. You get 0 volts inside the main service entrance between ground and neutral, because they are one and the same at this point. The farther you travel from that point, the more voltage difference there will be. As current on a circuit increases, the voltage between neutral and ground will rise, because the neutral return path has a non-zero resistance, and therefore there is a voltage drop. A couple of volts between ground and neutral on a moderately to heavily loaded circuit isn't likely an indication of a problem. If it's more than a few volts, it's wise to try to shut power off and re-torque things. Neutral to ground voltages are a separate issue to the shocking phenomena - or at least it better be. Absolutely NOTHING connected to either the neutral or hot wires should be exposed out of a device. [/QUOTE]
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