JMP-1 no leds or number display working.

Discussion in 'Marshall Amps' started by Waldog, Jun 14, 2019.

  1. Waldog

    Waldog Member

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    Hi all,
    I’m looking to buy a JMP-1 but the buyer says that none of the leds light up including the number displays. Sometimes they light up when it’s first turned on but then they stop working. Other than this it works fine and the price is right.
    Has anyone come across this before? I’m hoping to open it up and find a dry solder joint somewhere that’s an easy fix.
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    It could be broken solder connections, cracked circuit board, failed power supplies.
    Be careful how much you pay for broken gear.

    The components are static sensitive, one spark of static and it blows the processor.
    Special anti-static soldering equipment is required to work on gear like this.

    Also: replace the CMOS battery. Install a battery holder on the board.
    But this can also damage the circuit tracks if you don't have the equipment and the skills to work on PC boards.
     
  3. Micky

    Micky Well-Known Member VIP Member

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    Have you tried a complete hard reset?
    Also might be the battery is dead...
     
  4. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    Don't fry that EPROM...................
     
  5. peterplexi

    peterplexi Active Member

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    Hey guys! Do yourself a favor and send it to Tommy Folkesson and have him do the "Eternal Classic Jmp-1" mod. You will not be disappointed. He would obviously fix the issue as well without a problem.
    Cheers!
     

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