*URGENT*** MY MESA 400+ HAS STOPPED WORKING.

Discussion in 'Amps and Cabs [BG]' started by scottblessed, Jun 15, 2008.


  1. Using it at practice right now. In all honesty, I was driving the amp pretty damn hard. I'm using a y split cable and running input one at 2, input 2 at 4, master at 9. It was sounding great, got to the end of our third song, the volume totally dropped, just leaving a really thin signal coming through, then the amp turned off.

    Pulled out the fuse and it has blown. replaced it and the amp turned on, it came on but as soon as I put it off Standby, it blew again. All tubes are glowing fine, but there is an awful smell, kinda like solder, maybe that is Just the fuse (i hope) or have I burned out the circuit?


    Please. any help is appreciated.

    Scott.
     
  2. Take it to a tech immediately! Do not pass go, do not attempt repair by your self. Danger and possibly fatal out come for you and the head.
     
  3. Take a metal rod and start poking at while standing in water without shoes on.

    In other words, if you don't know, take it to a tech. Tube voltages are lethal.

    I have had tube heads throws fuses when a power tube went bad. So you can try an easy swap out if you have a matching biased tube.
     
  4. anderbass

    anderbass

    Dec 20, 2005
    Phoenix. Az.
    My 400+ was blowing its fuse when I first bought it. My issue was being caused simply because one of its power tubes had rattled almost all the way out of its socket. After pushing the tube back in (and re-tensioning its loose bear-claw retainer clamp jaws to keep it in) I never blew another fuse.

    I never experienced your "thin sound and burnt smell" symptoms with mine... Yours may very well have other much more serious internal problems that would definitely require an amp tech.

    Make sure your using the corect replacement fuse and be aware that every time you try another fuse and it blows, you may be doing even further damage to your amp.
     
  5. KeithPas

    KeithPas

    May 16, 2000
    Poulsbo,Wa
    Did you check to see if you may have blown the fuse?
     
  6. BassmanPaul

    BassmanPaul Inactive

    If you have a burning smell turn the amp off and take it to a tech. Do not try and fix the amp yourself.

    Keith did you read the OP in its entirety?

    Paul
     
  7. DanielleMuscato

    DanielleMuscato

    Jun 19, 2004
    Columbia, Missouri, USA
    Endorsing Artist, Schroeder Cabinets
    Glad to see Keith is paying attention :smug:

    Take it to a tech. This is why I bring have two backup rigs ;) And I don't even use tubes!
     
  8. The other guys have already said it, take it to a tech. Fuses don't go bad, something pushes them over the edge. Somewhere your amp is running harder than it wants to.
    Good Luck, and let us know the outcome. :)
     
  9. D.A.R.K.

    D.A.R.K.

    Aug 20, 2003
    Virginia
    hopefully it is just a sacraficial resistor or two...
    apparently these are in place to prevent catastrophic damage to other parts of the amp (i had a400+ which i blew a few of these in at one point) . as stated, you need a tech, but at least these are relatively cheap...
     
  10. KeithPas

    KeithPas

    May 16, 2000
    Poulsbo,Wa


    Obviously not.:)
     
  11. BassmanPaul

    BassmanPaul Inactive

    LOL Nice one Keith! :)

    Paul
     
  12. So I took it to the closest Mesa repair man, which was something like 125 miles away.

    He opened the amp up, saw that the second row of resistors underneatrh the tubes had ALL blown. And totally melted!

    He reckons a bit of solder melted inside the amp when it was on and dripped somewhere it shouldn't have. So after all new resistors were fixed into place. He tested it and it was completely fine. All the crossovers and everything were nearly perfect. All the tubes were still completely fine, so no need for a re-tube.

    I took Psycho Bass Guy's advice and purchased a JJ 12AU7 to put into the pre amp section to see how much difference that makes. However, I'am very happy with the way the amp sounded before it died on me. So it will just be an experiment.

    Thanks for all the info guys.

    Scott
     
  13. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

     
    Sep 26, 2021

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.