Electrical Shocks from Amp

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If your amp gives you electrical shocks, you probably have leakage of AC voltage to the chassis, either accidentally or by design. Either way is dangerous.

Note that if your equipment is properly three wire grounded and working correctly, other equipment that is leaking may shock you when you touch both of them, leading you to think that your amp is the one that is leaking. You'll have to test both pieces to find out which one is leaky.

Your amplifier should have a three wire AC cord fitted for the AC power for safety reasons whether it originally had this or not. If your amplifier HAS a three wire cord and still shocks you, there is more than one fault in operation, possibly including mis-wiring of the building's AC power outlets - it does happen.

If your amp is shocking you, you have to consider that the whole amplifier represents an electrical hazard to you, and might hurt or kill you under certain conditions. If you do not already know how to work on such faulty equipment safely, take the amplifier to a qualified service technician to fix.

To determine whether your amp is actually leaking AC, use a multimeter set to a range that will read at or over 125VAC. Plug the amp in and turn it on. Measure the AC voltage between the ground ring on the input jack and a known AC ground point, such as the chassis of a piece of equipment which is properly three wire grounded. This voltage should be zero. If it is over a volt or two, either your amp has a leakage problem, which is why you're getting shocked, or the equipment you're using for a ground reference has a fault in it which leaves the chassis un-grounded (which is unlikely)

If the voltage you read is over 30VAC, you have enough leakage to be dangerous to your health.

Finding the source of leaking AC

  1. Unplug the amplifier. Turn the power switch on.
  2. Measure the resistance of each flat prong on the AC cord plug to chassis ground. This resistance should be very high, but since you're getting shocked, probably isn't.
  3. If the resistance is very high, over 1M ohm, you have either
  4. If the resistance is lower than 1M ohm, there is a leakage path in the primary circuit.
Be certain that you re-solder any wires you removed during the debugging.