- 1). Begin by ruling out the obvious. If you are at a gig and your amp has no power or it seems underpowered, the problem might not necessarily be the amplifier. Check the power source. Bypass guitar pedals and plug directly into the amplifier. Make sure the volume and tone controls on the Fender amp are all turned up past 1.
- 2). Replace the fuse. If everything checks out but the amplifier still does not have power then the amp has blown a fuse. Remove and replace the old fuse. The fuse on Fender amps is in the back of the cabinet. It is covered with a black cylindrical cap marked "fuse." Twist the cap and remove it. Take the old fuse out and replace it with a new one. It is important to use the correct fuse. Fuse information is on the fuse and on the amp cabinet beside the fuse. Place the new fuse in the cap and insert it into the amplifier. Turn the amplifier on. If the fuse blows a second time this indicates that the amplifier has a more serious problem.
- 3). Inspect the power tubes. Power tubes should be replaced every one or two years depending on how often the amplifier is used. However, tubes are fragile and may go bad at any time. If your amp seems to lack clarity or have a muddy tone, this indicates that you have a tube problem. If the amp doesn't seem as powerful as it should be, this is also a symptom of a tube problem. When the amplifier is on healthy tubes should emit a soft amber color. A purple/bluish color indicates the tubes are weak and under powered. A harsh white color indicates the tubes are being overpowered, which is bad for the amplifier.
Power tubes should be replaced in pairs and they need to be biased. The amp's circuitry are designed for specific tubes. Fender amplifiers usually have between two to four power tubes. If a power tube goes out a gig replace it. Take the amplifier to a professional amp technician after the gig and replace the other tubes - 4). Inspect and change the preamp tubes if necessary. Preamp tubes have more longevity than power tube. They are the little tubes inside the amp that drive the preamp section of the amp. However, they eventually go bad as well. Symptoms of a bad preamp tube are unusual distortion sound and high pitched squealing noises. Preamp tubes may be replaced individually.
- 5). Repair the speakers if they are causing problems. Another cause of unwanted distortion is a ripped or torn speaker. A speaker that breaks up or has intermittent sound may be suffering from a loose cable connection. Remove the speaker grill with a Phillips head screwdriver. Inspect the positive and negative cable connections on the back of the speaker. If the connections seem loose or frayed, strip off 1/2 inch of insulation from the ends of the cable and solder the connection to the speaker. Remove the speaker if it is torn or ripped. Repair minor tears with tape or Elmer's glue. If the speaker is blown, the coil has melted or separated, it needs to be replaced.
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