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Master Lead 50 Watt Power Switch

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by TheAmpNerd, Jan 1, 2005.

  1. TheAmpNerd

    TheAmpNerd Member

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    I'm sure you' ve seen these or the
    JCM 800s. And even if you haven't

    They have an illumated switch for power,
    with fiive terminals wired as follows:

    BLU (tranny) ----X X ----- YEL (fuse)
    WHT (cord) -----X X ------ BLK (cord)
    wht to board ----X
    tie to black
    to tranny

    Now, if you follow standard wiring protocol, you would wire it similar as you found it. The extras white lead
    was taped and stowed.

    That works but it still isn't right, can any one
    guess why?



    The switch was fried and the bulb inside the switch didn't work, I took it apart to fix it----NOT.

    I'll write back tomorrow night and see if anyone knows
    what isn't correct about it. : )

    Yes, shame on me, I did fall asleep with out finishing it.
    LOL My nose must have hit the enter/return key.
     
  2. cap'n'crunch

    cap'n'crunch Member

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    Shhhhh! I think he fell asleep in the middle of the thread.
     
  3. Wakarusa

    Wakarusa Member

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    When you use the replacement switches with four terminals you can eliminate the "old" fifth wire. It was used to run the bulb and is not required in the new switch.
     
  4. John Phillips

    John Phillips Member

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    Unless you want to be able to use the voltage selector.

    The reason for the 5th terminal is so that the neon is driven from the 110V transformer tap (not the input line) no matter what the line voltage is.

    If you eliminate the 5th wire you must use a 240V neon (which will probably still work, but less brightly, on 110V) or it will blow if the amp is used on higher voltages.
     
  5. Wakarusa

    Wakarusa Member

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    Guess I never considered that... so are they offering a different replacement switch depending on country of origin? Last I checked the 5 pole switch had been discontinued.
     
  6. TheAmpNerd

    TheAmpNerd Member

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    I think so too.

    However, I did edit my incomeplete thread

    AND

    I've added the following.



    I promise not to tease you techies out there.

    I do TEASE my Dog Spot as shown here:

    [​IMG]

    He is so pissed he won't even look at IT.

    He stares at me to release him from his HELL.

    Any Questions?
     
  7. John Phillips

    John Phillips Member

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    Location:
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    The cord wires should be connected to the two end terminals, not the two in the middle of the switch, and the wires to the fuse and the transformer to the two in the middle.

    The neon is inside the rocker part of the switch, and it's wired to the two metal pins which operate the switching. If you have the cord connected to the middle pins, the light will be on all the time even when the amp is off.

    In the older scheme, the light isn't on unless the circuit is completed via the transformer and the 5th terminal, but it needs the neutral connection directly, so it's correct as you drew it.


    FWIW, you can take those switches apart and fix them. Yes, it's a pain. I do it though, for exactly the reason that you can't get the 5-terminal switch any more. You need to carefully prise out the rocker, pop off the red cover, and change the neon - fiddly even with practice.

    Just for the record, this is the most common component failure on a JCM800 too. They really are extremely reliable and well-made amps.
     
  8. TheAmpNerd

    TheAmpNerd Member

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    John - You get the Rawk of the week award.
    I'm impressed.

    Yep! And when the same switch didn't work any longer,
    I took it apart and it just fell apart.

    I didn't think too hard about it until I plugged it in
    and the switch was illuminated all the time;
    Just the opposite the original problem,
    besides being intermittant, no illumination.

    Plug ends on the top.

    Extra wire taped and stowed.

    :dude

    Anyone else working on these will save you some time.
     

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