How to Repair a Fender Tube Amplifier

By | April 10, 2021


Start by excluding the obvious. If you are at stake and your amplifier has no power or it seems underpowered, the problem may not necessarily be the amplifier. Check the power source. Pass the guitar pedals and connect directly to the amplifier. Check that the volume and tone controls on the Fender are all above 1.


Replace fuse. If everything checks out but the amplifier still does not have power, the amplifier has blown a fuse. Remove and replace the old fuse. The fuse on the Fender ampere is located on the back of the cabinet. It is covered with a black cylindrical lid marked ‘fuse’. Turn the lid and remove it. Take out the old fuse and replace it with a new one. It is important to use the correct fuse. Fuse information can be found on the fuse and on the reinforcement cabinet next to the fuse. Place the new fuse in the cover and insert it into the amplifier. Turn on the amplifier. If the fuse blows a second time, this indicates that the amplifier has a more serious problem.


Check the power tubes. Power tubes should be replaced every two or two years, depending on how often the amplifier is used. However, pipes are fragile and can go bad at any time. If your amplifier seems to lack clarity or have a muddy tone, this indicates that you have a pipe problem. If the amplifier does not appear to be as powerful as it should be, this is also a symptom of a tube problem. When the amplifier is on healthy tubes, it should emit a soft yellow color. A purple / bluish color indicates that the tubes are weak and below A hard white color indicates that the tubes are overloaded, which is bad for the amplifier.

Power pipes must be replaced in pairs and they must be prestressed. The amplifier circuits are designed for specific pipes. Fender amplifiers usually have between two and four power tubes. If a power pipe goes out, a gig replaces it. Take the amplifier to a professional amplifier after the show and replace the other tubes.


Inspect and replace pre-pipe if necessary. Pream pipes have a longer service life than power pipes. They are the small tubes inside the amplifier that drive the amplifier of the ampoule. But they eventually go bad. Symptoms of a poor pre-amplification tube are unusual distortion noise and loud beeps. Reinforcement tubes can be replaced individually.


Repair the speakers if they cause problems. Another cause of unwanted interference is a ripped or torn speaker. A speaker that breaks up or has intermittent sound may be affected by a loose cable connection. Remove the speaker grille with a Phillips screwdriver. Check the positive and negative cable connections on the back of the speaker. If the connections appear loose or worn, remove 1/2 inch of insulation from the ends of the cable and solder the connection to the speaker. Remove the speaker if it is broken or torn. Repair minor tears with tape or Elmer glue. If the speaker is blown, the coil has melted or separated, it must be replaced.

Tips and warnings

  • Always keep replacement tubes, fuses and a screwdriver in your gig bag.
  • Bring the amplifier in for a set-up by a professional official once a year. Tube amplifiers contain dangerous amounts of electricity. In addition to the tubes and speakers, the technology can inspect the capacitors, resistors and transformer.
  • Leo Fender set the standard for guitar amps. Fender is still the booster of choice for many guitar players. Fender’s main competition in the 1960s was the Marshall Company. Jim Marshall’s amplifier was modeled after Fender’s’ 59 Bassman. Leo Fender applied his expertise in radio-vacuum tube technology to design and build amplifiers for lap steel and electric guitars, which he also created. Fender tube amplifiers use much the same technology that Leo Fender developed in the 1950s. Tube amplifiers sound warm and rich but regular care and maintenance are necessary to keep them in good condition. If your Fender amp does not sound as good as it used to, it’s time to make some repairs.