Maintenance and Care

• The 5150 amplifier has a standby switch. Use it. Allow the amplifier to sit in the standby position for at least 30 seconds. The power tubes warm up to an optimal level, ensuring that undue stress isn't put on the tubes. Power tubes are the No. 1 recurring expense of owning a tube amplifier, but using the standby function can help control costs. Do not leave the amp in standby mode for more than 10 minutes as this can hurt the tubes.
  
  

Troubleshooting Basics

• It is widely considered that faulty power tubes cause 90 percent of the problems in tube amplifiers like the 5150. If your 5150 was purchased secondhand and it is creating undesirable tones, blowing fuses, squealing, humming, hissing, making popping noises, has low volume in different or all channels or works for a moment and cuts out, consider installing new matched power tubes (6L6s) and preamp tubes (12AX7s). These symptoms can directly relate to tube failure. If you don't do this first, you will be working with unknown variables when troubleshooting the other sections of the amplifier.
  
  

More Troubleshooting Suggestions

• If the fuse is blowing on the amplifier, even after changing the tubes, do not keep replacing the fuse and attempting to turn the amplifier on again and again. You can cause more damage by doing so. The fuse blows only when there is something wrong. It will never blow if power is entering the amplifier correctly.
  
  

Cleaning

• Many issues arise in the 5150 if it is dirty or has had something spilled on it. Use an electronics cleaner on each knob and rotate the knobs while the electronics cleaner penetrates. Remove all dust and dirt buildup along the crevasses and back of the amplifier. Clean the input jacks with the electronics cleaner sprayed on a cotton swab and ensure that they are screwed tight at the nut to the chassis.
  
  

Additional Repair

• If these several options have not solved the issue with your 5150 amplifier, you'll want to take it to a qualified service tech. It's likely that the 5150 will need to be disassembled and diagnosed from the inside out. This amplifier has large capacitors containing high levels of energy that can be fatal. Explain what work has been done if you decide to take your amplifier to a technician. They'll appreciate knowing where you left off, which could pay off in a low service charge.