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  1. R

    ‘78 JMP 2203 Impedance Selector

    Interesting, I’m really new to amps and a lot of this is still new to me and definitely haven’t heard a lot about these but finding out a lot just from wanting to know whether the impedance selector is set up as original… 😂
  2. R

    ‘78 JMP 2203 Impedance Selector

    No, wasn’t sold as original either. PO said he had it for about 20 years and only had the mains output fixed and it set up for 16 ohm cab which it ran through no bother upon testing. Didn’t know much about previous owner or work done
  3. R

    ‘78 JMP 2203 Impedance Selector

    I know it needs fresh tubes etc, even I can tell that! So is the impedance selector going to act normally as it’s currently wired? Ie 8ohm is where it should be as if it were stock, 16 ohm and 4ohm the same?
  4. R

    ‘78 JMP 2203 Impedance Selector

    Like this?
  5. R

    ‘78 JMP 2203 Impedance Selector

    As far as I’m aware, all the parts (bar valves etc) are original and the only mod the previous owner said was that the power selector was hard wired at 240V
  6. R

    ‘78 JMP 2203 Impedance Selector

    Looks like the same wiring configuration but different colour coding? I have green+purple on one pin where that is green and black, yellow on mine where that has green and brown where it has yellow. Does this mean it’s standard and marshall just weren’t consistent with colour coding?
  7. R

    ‘78 JMP 2203 Impedance Selector

    Hi, these are the internals, do they look stock on the selector?
  8. R

    ‘78 JMP 2203 Impedance Selector

    What would I be looking for on the internals? I’m not terrible with circuits but I’m not brilliant with them either, not great with the circuit diagrams
  9. R

    ‘78 JMP 2203 Impedance Selector

    Hi, recently picked up a 1978 JMP 2203 and I’m confused about the impedance selector. It’s not an original and doesn’t have the little window to say which impedance it’s running at, just an arrow pointing away from any of the markings. The previous owner had it connected to a 4x12 in mono and...

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