How to Troubleshoot a Fender Tank Reverb
- 1). Replace the reverb tubes with new tubes. If the reverb unit works, then bad tubes were the problem. Some Fender amps use one reverb tube and other Fender amps use two.
- 2). Look inside the back of the cabinet and gently lift the reverb tank out of the amplifier. It is enclosed in a black cover. Remove the black cover.
- 3). Unplug the input and output cables and plug them in again. The input cable causes the springs to vibrate. The output cable detects the vibrations. The vibrations sometimes cause the cables to become loose.
- 4). Look for loose or broken wires in the input and output cables. If there are broken wires, strip off the insulation with wire strippers and reconnect the wire.
- 5). Straighten out minor kinks or bends with a pair of pliers. Lubricate the springs with a lightweight motor oil. Replace the springs if it is not possible to remove the kinks.
- 6). Place the reverb tank back inside the amp. Put the reverb tank back inside the black cover and set it gently in the bottom of the amp. Plug your guitar into the amp. Turn the amp on and test out the reverb.
Source...