Just Blew Amp - Help!

Discussion in 'Amps and Cabs' started by JTWUSMC, Jan 18, 2015.

  1. JTWUSMC

    JTWUSMC Member

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    I just got done putting my 1981 Music Man RD back together after replacing a bad cap, new speaker and new tubes. I plugged it in and pop (at the outlet the second I plugged her in), smoke coming from the amp (no distinct smell). It wasnt turned on or anything, just blew as soon as the plug hit the outlet.

    I dont think the repair had anything to do with it because ive played it several times since the repair, just with the chassis removed. All i did today was put the head back into the cab and put in a new speaker - 8 ohms to an 8 ohm input.

    Any ideas on what can cause it to immediately blow when plugged in while its turned off?
     
  2. ked

    ked Supporting Member

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    Possible short in the main cord.
     
  3. slider313

    slider313 Silver Supporting Member

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    It sounds like a power cord issue.
     
  4. Dan40

    Dan40 Supporting Member

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    Like the guys above mentioned, if the power switch was in the off position then the problem would seem to be the power cord. Also check all wiring inside the chassis from where the cord enters all the way to the power switch. Make sure that nothing bare is touching the metal chassis.
     
  5. TheoDog

    TheoDog Silver Supporting Member

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    Seems there might be a compromise on the cable- as mentioned.
    Fuse ok? Maybe put a surge protector on the next outlet. Small chance the fault could be house wiring.
     
  6. Jason_86_951

    Jason_86_951 Supporting Member

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    Does the head shell have a metallic shielding plate? Could the power wiring be touching this after being put back into it?


    As for your thread title....lol

     
  7. davebc

    davebc Member

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    Your bringing back some very band memories from the mid 70's
    When I blew 3-4 music man amps.:facepalm

    And for whatever it's worth those trannies are really vulnerable.

    Good luck and Godspeed
     
  8. JTWUSMC

    JTWUSMC Member

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    Thanks for the input. Ill check tomorrow for the power wires. The fues was decimated btw. Melted the wire beyond recognition.
     
  9. davebc

    davebc Member

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    They always sounded the best right before they blew...:facepalm
     
  10. billyguitar

    billyguitar Member

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    Look up Ed Goforth. He is the MM guru.
     
  11. davebc

    davebc Member

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    The thing is Music Man amps sounded so good, especially for the time!
    They sounded phenominal with Gibsons or Fenders, no pedals.
    Like the ballsiest Fender you could ever dream up, an el34 Fender.
    But they were just not reliable.
    I kept going back for more, but after the 3rd or 4th one, I was time to move on.

    And I know someone will chime in and say I've had mine since they came out and never
    had a problem.
     
  12. straightblues

    straightblues Member

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    Kevin Nelson is a southern California (Garden Grove) amp guy. He worked for MusicMan and designed a lot of those amp. Check the schematic you may find his name on it. He bought out a lot the parts when MM stopped making amps. He probably has original parts to replace whatever you need. After some health issues, he now works out of his house doing repairs and building custom amps. If you need a consult or parts, get in touch with Kevin. Here is his email address in case you want to reach him. gizmoeamps@netzero.net
     

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