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Amp troubleshooting

Discussion in 'Amps and Cabs [BG]' started by Pea-NUT, Jan 13, 2002.

  1. Pea-NUT


    Jul 1, 2001
    Jerseyville, IL
    I need some help. ALOT of help. Need to fix a guitar amp. Willing to do almost anything. Its a Peavey backstage or close to it. Its under 100 watts i know. I think there is something blown:rolleyes: or there is a short somewhere in it.
    I can put a new fuse in it, turn it on, and boom, fuse is gone. Not exactly *BOOM* but it just goes out. Is there any sites that have a troubleshooting thing for this type of stuff. I have about everything to fix or can get it. Maybe its just shot. I dont know.
  2. Pea-NUT


    Jul 1, 2001
    Jerseyville, IL
  3. Do you have the right size of fuse?

    Be sure that it is slow-blow so that the "start up current" wont blow the fuse. Had the same prob with my Mesa 400+, then I discovered that the fuse wasnt slo-blo .. fixed it and: Never blown a fuse since!
  4. I don't know the amp in question but...which fuse are you talikng about: an ac power fuse; a speaker line fuse; a DC supply fuse?

    If it's blowing fuses in the plug on the power cord then the fault is most likely to be in the amps power supply. Shorted turn on the transformer, one or more arms of the bridge rectifier (assuming it's a full wave bridge) gone short, the smooting capacitor(s) short.

    If power cord plug fuse is the symptom, see if you can disconnect both the + and - supply rails from the main amplifier. Then try again. If the fuse still blows then the power supply is almost certainly at fault. If it doesn't blow, just for reference, measure the + and - voltage wrt the centre rail / 0V line.

    If it's a speaker line fuse or a DC line fuse then the power amp is almost certainly at fault. You might well have more problem fixing that without a circuit diagram.


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