Troubleshooting
Pilot lamp not lit:
Is the amplifier plugged into a functional outlet of the appropriate voltage?
Is the mains fuse blown? If so, replace with the appropriately rated fuse. If the fuse
again blows, the amplifier may have a shorted output tube or blown rectifier diodes.
Replace the tubes and fuse, and power the amplifier up again. If the fuse still blows, the
amplifier will need to be serviced. If tubes don’t fix the problem, it is most like the rectifier
diodes that are bad, and they should be replaced first.
Pilot lamp lit, but no sound, low sound, or intermittent sound:
Is the HT fuse blown? If so, replace with the appropriately rated fuse. If the fuse again
blows, the amplifier may have a shorted preamp tube, output tube or rectifier tube.
Replace the tubes and fuse, and power the amplifier up again. If the fuse still blows, the
amplifier will need to be serviced.
Is the speaker functional and plugged in correctly? Insure the amplifier's output
impedance selector is correctly set to match the speaker in use.
Is the guitar cord functional? Bypass any pedals and plug straight in with a known good
cable to test.
Is the effects loop jack dirty or broken? Try plugging a cord into the effects loop jack and
back out several times to “clean” the jack contacts. If the sound comes back, you may
need to take the amp in for replacement of the jack or for cleaning of the switching
contacts on the jack (these bypass the loop when nothing is plugged in, and may get dirty
and become intermittent). In a pinch, you can buy a stereo plug from Radio Shack and
solder the tip and ring terminals together and plug it back into the effects loop jack. This
will be a removable “bypass” plug that will allow the amp to properly function if the effects
loop jack has become intermittent or the switching contact has been broken.
No effects:
Is the insert cable fully plugged into the jack on the back of the chassis?
Is the effects unit designed for pro level (0dBu nominal, +4dBu max) levels? The Intruder
will not work with “stompbox”, or guitar-level effects, as they are designed for very low
guitar signals.
Is the effects unit in bypass mode?
Does the signal presence LED (if there is one) on the effects unit light when you hit a
chord?
IntruderMKIIManual.doc 06/17/13 Page 14 of 17
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