One of the most desirable qualities in Fender amplifiers is the famous Fender reverb. The technology behind Fender reverb is very basic and simple. The reverb unit is a spring activated device that has two long springs. It sits in the in a tank in the bottom of the amplifier cabinet. The amp sends a electrical signal that causes the springs to vibrate. If you are having a problem with the reverb on your Fender amplifier, the problem is easy to diagnose and correct.
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Make sure the footswitch in turned on. Turning the reverb on is a two-step procedure on Fender amps. The reverb knob on the amplifier has to be adjusted; it goes from 1 to 10. There is also a footswitch that has to be clicked to the "On" position. There is not an LED light to indicate if the switch is on or off. The only way to know if the switch is on is by playing the guitar with the reverb knob on the amplifier turned up past 1. If you click the footswitch a couple of times and still don't have reverb, check the footswitch input jack.
Check the footswitch input jack. If you click the footswitch on and off a couple of times and still have reverb, make sure that the footswitch is plugged into the input jack in the back of the amplifier. If it is plugged in, unplug it and plug it back in. Test the tremelo function; the tremolo effect uses a different button on the same footswitch. If you have problems with the tremelo as well, there may be a short in the footswitch.
Inspect the reverb-unit tubes. Some Fender amps use one tube to activate the reverb, and other Fender amps use two tubes. Read the instruction manual for your Fender amplifier. Find out which tube is responsible for controlling the reverb unit. Replace the tubes with duplicate tubes, and test the reverb.
Remove the reverb tank. The reverb tank sits in the bottom of the cabinet. Remove the cover and carefully remove the reverb tank from the amp cabinet.
Look at the input and output cables to the reverb tank. The input cable connects to a transducer that vibrates the springs. The output cable connects to a transducer that detects the vibrations. Make sure both cables are firmly plugged in. Check inside the tank for broken wires leading to the transducers; this is the most common problem. The vibrations from the springs will break the wires over time. If a wire is broken, strip off 1/16 inch of insulation and solder it into place.
Examine the springs. There are two springs in a Fender reverb tank--examine both springs, and make sure that they are in good shape. Look for kinks, bent springs and gaps. Lightly spray the springs with a lightweight motor oil.