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  • 50 watt jmp 76

    O.K. guys, i got a problem, all of a sudden the volume on my amp dropped to almost nothing.The volume and master volume are maxed out and i can still talk louder than it in a normal voice.I would love some imput. Thanks.

  • #2
    What have you tried so far???

    Tube swap?
    Did you try a different cab?
    Guitar?
    Speaker cable?
    Guitar cable?
    Are there any effect pedals in use AND have you tried removing them?
    Did you try cleaning all the jacks?
    Have you cleaned and retentioned the tube sockets?

    This would be a place to start. Let us know what you find.

    Chuck
    "Take two placebos, works twice as well." Enzo

    "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

    "If you're not interested in opinions and the experience of others, why even start a thread?
    You can't just expect consent." Helmholtz

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    • #3
      50 watt jmp 76

      Thanks for responding. I've tried everything except retentioning the tube sockets.I'll take a shot at that tomorrow ,and let you know what happens. Thanks again. TVJR

      Comment


      • #4
        Dirty sockets would have tipped you off when you did the tube swap because you would have probably either heard some ugly noises or the amp might have worked intermittantly.

        If you've tried everything on the list the next step is to crack it open and take some voltage readings.
        "Take two placebos, works twice as well." Enzo

        "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

        "If you're not interested in opinions and the experience of others, why even start a thread?
        You can't just expect consent." Helmholtz

        Comment


        • #5
          Chuck ,I thank you for your help but voltage reading is where i get lost. Quick question. With the amp running i do get sound and it is a constant,but the volume is very low.It doesn't cut in or out.When checking the pre amp tubes,If i pull a tube is the sound supposed to cut out completly. It does, no matter which pre amp tube i take out i lose all sound , is this right. thanks again tvjr.

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          • #6
            Pulling any pre amp tube will cut the signal path. If the amp were working at proper volume you could isolate hum and noise by pulling pre amp tubes.

            With your amp two common failures with your symptoms are blown screen resistors and a blown output transformer. Whatever the problem is you need to either crack it open or take it in for repair at this point.

            I owned two of those amps at one time. It's the 50 watter with the master volume, two inputs and the goofy big square illuminated power switch, right? One was an early example with the mustard caps and the other had the white box caps. I hate to admit it because I don't believe in mojo but the one with mustard caps always sounded better. I bought the first as a gig backup for my 1959 (not an original) and the second because I liked the first one so much. These are under appreciated Marshalls IMHO
            "Take two placebos, works twice as well." Enzo

            "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

            "If you're not interested in opinions and the experience of others, why even start a thread?
            You can't just expect consent." Helmholtz

            Comment


            • #7
              50 watt jmp 76

              Yep , thats the one. I have the amp out of the box,Can't find anything visable wrong . I'll keep looking,if no luck i'll call a friend of mine who can help. I was just trying to figure it out myself.Thanks for all your help. tvjr

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