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HELP! Sub plate amp blows power fuses

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  • HELP! Sub plate amp blows power fuses

    Anyone recall problems with this old plate amp?
    We have a new Subwoofer Plate amp 300-793 with remote control for the xover and gain adjustments. This amp predates the one currently listed on Parts Express site under 300-793.

    The amp is new, in box, never been used. We were intending to sell it, so thought I had better verify that it works. Alas, it blows the power fuse at the power cord input every time when powered on!

    Was this a common fault with these amps? Is there a simple component to replace?

    All help appreciated.

    Thanks,
    Marvin

  • #2
    Did the unit blew fuses from the very first time it was turned on?

    Picture of the PCB might help.

    Comment


    • #3
      Originally posted by Millstonemike View Post
      Did the unit blew fuses from the very first time it was turned on?

      Picture of the PCB might help.

      I do not know if it has ever been tested after purchase. It belongs to a cousin who has had it on the shelf for years.

      Here's more pics:
      Attached Files

      Comment


      • #4
        Nothing obviously suspicious there. When you attempt to power it on are you making sure the front panel is connected and the speaker leads are clear and not touching anything?
        Electronics engineer, woofer enthusiast, and musician.
        Wogg Music
        Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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        • #5
          Try moving the 230 V - 115 V switch back and forth a few times and then make sure it clicks into the 115 V position.

          Comment


          • #6
            Originally posted by wogg View Post
            Nothing obviously suspicious there. When you attempt to power it on are you making sure the front panel is connected and the speaker leads are clear and not touching anything?

            Yes. The remote/adjustment control panel is plugged in. I have tried powering up with a speaker connected and also with the leads clear. It is interesting that it blows the fuse even with the power switch in the off position.

            Comment


            • #7
              I think I will bring it to DIY Iowa to see if any amp techs are interested in it.

              Comment


              • #8
                If it blows with the power switched off means there is a short in the circuit between the power switch and plug so that should be fairly easy to find. Do you have a multimeter?

                Dan

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                • #9
                  Oh it looks like it's not a traditional power switch with 120v full current running through it. Either way you have a short. Too bad you can't simply remove the transformer and such wires from the boards with easy plugs. That would make the job much more simple.

                  Dan

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                  • #10
                    Install a slow blow fuse of the recommened amperage.
                    "Our Nation’s interests are best served by fostering a peaceful global system comprised
                    of interdependent networks of trade, finance, information, law, people and governance."
                    - from the October 2007 U.S. Naval capstone doctrine
                    A Cooperative Strategy for 21st Century Seapower
                    (a lofty notion since removed in the March 2015 revision)

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