Amplifier Blows Fuses

Your amp is blowing fuses:

When the Hi T fuse blows it's usually the time to change output tubes. If you do get new power tubes be sure to get the amp biased.

  • Do not replace with a fuse that has a larger amperage rating under any circumstances, higher voltage rating is OK, usually 250 volts.
    100 watt amplifiers require 3 A or 4 A. Always try to use SloBlo fuses.

  • Look for any broken tubes, they will appear white instead of silver.

  • Check for an arced-over tube socket, it will have to replaced before using the amp again.

  • On a 100 watt amp, try removing two of the tubes, #'s 1 & 4. Then put them back and try #'s 2 & 3. You can safely run on only 2 tubes.

  • Try a different speaker cable and speaker cabinet.

  • Check for loose speaker impedance selector if you own a JMP Marshall.

  • Check the voltage selector if there is one - set for 120 volts not 110 volts.

  • If the fuse doesn't blow immediately then tap on each power tube to weed out any bad ones

  • Open the amp and check for anything loose that could be causing a short circuit

  • Remove all preamp tubes and replace if necessary

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