How to Repair Tube Guitar Amps
- 1). Replace the capacitors in your preamp section if your amp makes a putting noise, often referred to as "motor-boating." This noise may occur when you are playing or when the amp is taken out of standby mode. Though this problem can usually be fixed by simply replacing the capacitors in the preamp, you might consider replacing all capacitors, as this generally only happens after capacitors have been in place for several years or more. Replacing all of the capacitors at once can mean fewer headaches later.
- 2). Fix humming noises in your guitar amplifier by checking for blown tubes. Faulty tubes are the most common cause of excessive hum. Look in the back of your amplifier for tubes that are not lit or are very dim. Turn the power off and remove any tubes that are obviously broken. If this does not fix the problem, pull tubes one by one to test them. Removing one tube from the amplifier will not cause any noticeable performance problems during testing.
- 3). Check the AC grounding if removing tubes does not get rid of excessive hum. If you have a non-grounded plug on your amplifier, you should purchase a ground lift or have a grounded cable put on your amplifier (see Resources for more on ground lifts).
- 4). Fix unintentional distortion by checking the speaker cone or cones for tears. If the speaker is torn, you can use clear silicone adhesive to patch the paper on the cone. Let the adhesive dry overnight before testing the amplifier. (See Resources for a link to buy clear silicone adhesive.)
- 5). Check your tubes to make sure they are working if the power indicator glows, but you are getting no sound. A common cause of this problem can be a blown rectifier tube. Simply replace the rectifier tube with a new working one to test for this problem. If tubes are not the problem, check to see if there are frayed or disconnected cables leading to the power transformer. If this is the case, fix and reconnect the cables. If you are unfamiliar with this process, it is best to take your amplifier to a professional technician.
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