Thu 3 May 2012
How to wire a mains earth to a US amp with 2 prong cord. NOT!
Posted by Frank under Amp repair, Guitar Amps, Vintage amps
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When you think you’ve seen every conceivable bodge job on the planet, something comes in that beggars belief.
Here are some snaps from an amp I’ve just worked on.
The amp is US voltage Ampeg Gemini. Someone had installed a step down transformer into the bottom of the cabinet to allow operation from UK mains. So far so good.
The amp had its original 2 prong US mains lead without a safety earth connection. This is obviously unsafe, and is conventionally remedied by fitting a new 3 prong mains cord and securing the earth to the chassis with a star washer and bolt.
A previous repairer had obviously decide that a new 3-prong mains cord with earth connection was frivolous luxury, and so came up with a novel solution.
Firstly a new earth wire was connected to the vacant earth pin in the female US socket coming from the step down transformer using a wood screw.
Then the other end was “securely” soldered to a ready made hole in the chassis. A light tug and the wire came free.
Good work!!
Suffice to say I fitted an earthed 3 prong mains cord before I powered up the amp.











