How to Test Fender Reverb Tanks

Written by robert russell
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Fender amplifiers set the standard for amplifier reverb. The reverb function on Fender amps is a simple spring-activated device that sits in the tank, typically in the bottom of the amplifier. The amplifier sends a signal to the tank that causes the springs to vibrate. A transducer in the tank detects the vibrations and sends the signal back to the amp. If the reverb unit on your Fender amp stops working, the problem may be as simple as plugging in a loose reverb foot switch.

Skill level:

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Things you need

  • Soldering iron
  • Screwdriver
  • Replacement tubes
  • Reverb driver transformer

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  1. 1

    Check the reverb foot switch. The reverb foot switch on Fender amplifiers does not have an LED light to indicate when the reverb is turned on and off. Adjust the reverb knob on the amplifier to at least two or higher. Play your guitar and listen for the reverb. If the amplifier is not producing reverb, step on the switch and play the guitar again. If you still don't hear reverb, step on the tremolo button. The tremelo button and reverb button are on the same foot switch. If the tremelo doesn't work as well, there may be a problem with the foot switch. Check to see if the foot switch is plugged correctly into the amplifier. Another option is to replace the footswitch with another reverb switch to see if it will turn the reverb funtion on.

  2. 2

    Check to see if the reverb tank is plugged in. The reverb tank plugs into an input jack in the back of the amplifier. The reverb sits in the bottom of the amplifier cabinet. Shake the tank. If you hear a loud springy noise this indicates that the circuitry is OK.

  3. 3

    Remove the tank and check the input and output jacks. The input jack connects to a transducer that vibrates the springs in the tank. The output jack is connected to a second transducer that senses and amplifies the vibrations. A common problem in reverb tanks is a broken wire between the jacks and the transducers. Check for broken wires. If the wire is broken, cut out the bad section and resolder the wire. Replace the wire if necessary.

  4. 4

    Inspect the reverb springs in the reverb tank. Fender reverb tanks contain two long springs that sit in the bottom of the tank. If the springs are bent or broken, they need to be straightened or replaced.

  5. 5

    Replace the reverb tube or tubes. Your Fender amplifier will have either one or two tubes.

  6. 6

    Locate the driver transformer in the back of the amplifier. The driver transformer is a large silver or black cube that sits near the reverb tank. If the driver transformer is blown, this will cause the reverb tank to fail. There are two methods for testing the transformer: Check it with an ohmmeter, and install a second driver transformer in the amp to see if it corrects the problem.

Tips and warnings

  • Opening your amp's circuitry will expose you to lethal voltages. Do not attempt unless you are experienced in handling high voltages.

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