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Ampeg B200R repair

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  • Ampeg B200R repair

    Hello! Got a B200R on the bench, all Mosfets and mosfet drivers are shorted. Tracked it down to the “without horn” input of the cabinet being shorted to ground. Is this a problem with the crossover board? Any way to fix it? Would love to be a hero and fix the original problem instead of putting a cap on it so it can never be used again thanks!

  • #2
    It is probably an issue with the wiring internally as the crossover is used for the horn. To fix the crossover will be simple I would think as it is not complicated.
    If you cab replace the FETs and drivers then set it up, shouldn't be an issue.
    Be methodical and you will be there before you know it.
    Support for Fender, Laney, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk
    If you can't fix it, I probably can.

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    • #3
      It reads a short to ground with only a jack plugged in.. nothing in the amp itself is relevant to the short in the speaker. With horn input reads 4 ohms as it should! So basically if it’s plugged in it will short out the fets and drivers again. Just wondering if anyone has fixed this before! Due to a genius design on the part of ampeg, it’s impossible to get to the speaker

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      • #4
        The speaker and crossover/sockets were fitted in the first place so I would think it will be front loaded but there is no photo that I can find so I don't know for sure.
        Usually removing the front grille will expose the speaker mounting screws and allow access to the socket panel through the front.
        It must be serviceable as I can't see Loud Technologies would throw all faulty speakers cabinets away.
        Have you got any photos of the cabinet?
        Support for Fender, Laney, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk
        If you can't fix it, I probably can.

        Comment


        • #5
          The front grille pulls off and the speaker is behind it.
          Attached Files
          Support for Fender, Laney, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk
          If you can't fix it, I probably can.

          Comment


          • #6
            I have not had a chance to work on a B200R.
            From what I can gather, the Chinese ones have an issue with the jack board.
            https://valvetubeguitaramps.com/ampeg-b200r/
            And there are issues with a very thin chassis cracking from the transformer weight.
            https://www.talkbass.com/threads/ano....996550/page-2
            Here is the schematic with the x over: ampeg B200R.zip

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