How to Install a Grounded Three-Prong Cord on a Blackface Amp

Blackface amplifiers were made by Fender in the mid 1960s. During that time it was common that most electrical devices, including the Blackface amp, used a two-prong plug. The two-prong plug is not grounded and can lead to the amp being sensitive due to no ground polarity. Fortunately, you can modify your Blackface amp to install a three-prong plug and safely ground it. Not only does this modification make the amp less sensitive, it will increase the safety of the amp so it does not burn out due to an electrical spike.

Screwdriver
Jumper cable
Wire cutter
Solder tip
Solder

Instructions

- 1
  Unplug the amp. Remove the back of the casing with your screwdriver.
- 2
  Locate the capacitor. Do not touch the capacitor with your hands as it still has power. Hook up one end of the jumper cable to the power tube plate (Tube V2, pin 7). Connect the other end of the jumper cable to ground lug (Tube V1, pins 6 and 1) for about one minute until the power is drained from the amp.
- 3
  Cut the black and white wire from the old two-prong power cord with the wire stripper. Pull the old plug from the amp.
- 4
  Put the new three-prong cord through the hole where the old cord was installed.
- 5
  Solder the black and white wire from the new cord to the same location where the old black and white wire from the old cord was installed. Plug in the solder tip until it is hot and place the hot tip to the end of the solder so the solder lands on the end of the cord and solders the wires in place.
- 6
  Solder the green wire from the cord to the ground lug on the capacitor (Tube V1, pins 6 and 1). Replace the cover on the amp and secure it in place. Your three-prong plug is now safely wired and will provide ground to your Blackface amp.

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