How to Repair My Fender Twin Reverb

The Fender Twin Reverb is an iconic amplifier, noted for its bright and clean reverb. Fender makes a reissue of this amplifier based on the original but made with more modern parts. As with all tube amplifiers, the Fender Twin Reverb requires ongoing maintenance and occasional repairs. Some repairs are fairly straight forward, while others require advanced knowledge of electronics. The key to repairing your Fender Twin Reverb amp lies in troubleshooting the problems.

• 1
  Use a new cable when troubleshooting the amp. guitar cable image by Darko Draskovic from Fotolia.com

  Plug in your guitar and turn the volume dial to zero. Power up the amplifier and wait for the pilot light to glow solidly. If the amplifier fails to power up, it is likely a problem in the power section. Unplug the amp and replace the fuse. Try the amp again. If the amp still fails to power up, disconnect it from the power supply.

• 2

  Remove the back panel of the amplifier and look for any burned out fuses or tubes in the power amp section. Replace any burned out fuses individually. If you spot a burned out power tube, replace all of the tubes in the power section. The Fender Twin Reverb takes four 6L6 power tubes. When the performance of a tube begins to decline, it puts extra demands on the other tubes and hastens their decline too. When one tube dies, the others are normally not far behind. Replacing them all saves you from repeated repair jobs and also eliminates the need to bias the tubes as tube sets are already biased.

• 3

  Turn on the amplifier and gradually increase the volume. If you are getting power but no sound, there is a problem in the preamp section of the amplifier. Unplug the amp and remove the back to expose the preamp. Replace your tubes and inspect the wiring. The amp takes four 12AX7 preamp tubes and two 12AT7 preamp tubes. If there is any loose wiring, disconnect it with your soldering iron and reattach it. While you have the preamp section exposed, use a cotton and plastic-safe contact cleaner to clean the potentiometers.

• 4

  Look for solder blobs. If solder drips on to the chassis or to the side of any wires during maintenance or repairs, it can cause a bridge in the circuit. That bridge can divert signal from its intended location to the wrong part of the amplifier. Often solder blobs are the cause of a weak signal and can also be to blame if the amplifier is pulsing. Pulsing is caused when the tremolo or vibrato unit spills into the signal chain via a solder blob. Melt the blob with your soldering iron.

• 5

  Inspect the speakers. The Fender Twin has two 12-inch, 8-ohm ceramic speakers. If one is torn, unscrew it and disconnect the wire. Replace it with a new one. If it is loosely connected, disconnect and then reconnect the wire.