Help please, wiring replacement Power Switch

Discussion in 'The Workbench' started by OdgeUK, May 8, 2020.

  1. OdgeUK

    OdgeUK Member

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    Hi all. Bought a modern Enec 1353 4-pin Rocker power switch for my 1978 JMP 50w 1987. The old one has 5 pins insteaf of 4, but I saw an online wiring guide that suggests the 5th wire is no longer needed on modern switches, as it takes a feed from the selector switch to light up the switch bulb. So I've wired like for like, minus the black, and the switch is permanently lit in either the on or off position and does not power the amp on.

    I have it wired like this currently (which was how the old 5-pin was wired
    [​IMG]

    Full size image here: https://i.ibb.co/Jtmq0HY/switch-gif.jpg

    I don't see how this relates to this:
    [​IMG]
     
  2. ampmadscientist

    ampmadscientist Well-Known Member

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    Do you have incoming power mains plug wired to 12 and 25?
    Do you have the primary of the power transformer wired to 11 and 24?
    Look at the numbers on the switch.
    Redundant black to voltage selector should be disconnected.
     
  3. South Park

    South Park Well-Known Member

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    Those switch’s are confusing . Take it out and test it to line up the contacts . Use a low voltage source
     
  4. OdgeUK

    OdgeUK Member

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    I do, but it's opposite. Power on 11 & 24, PT on 12 & 25. Which explains the bulb always on, but not the lack of output.

    Important question.. Does it matter which PT connect matches up with with mains connection? (I. E Live to PT yellow, Neutral to PT Blue, could be any which way?

    I used the continuity tester on my multimeter and the switch defo connects top horizontal lugs to bottom horizontal lugs.
     
  5. South Park

    South Park Well-Known Member

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    Disconnect the black wire
     
  6. OdgeUK

    OdgeUK Member

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    Already is. It's floating in the pic, there's only four lugs on the new switch.

     
  7. ampmadscientist

    ampmadscientist Well-Known Member

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    I don't understand "lack of output," please elaborate.
     
  8. OdgeUK

    OdgeUK Member

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    Update. Looks like when I was testing it originally, I had missed that there actually WAS output. Slightly compounded by the fact that the Power switch 'On' position was actually 'Off', but light on always, causing confusion.

    Looks to be fixed now by simply reversing the wires, so the mains Live and Neutral now on the top horizontal lugs, and the PT connections (one of which routes via the mains fuse) on the lower lugs (black left disconnected as no longer required in this type of switch). The switch now operates as expected. Sadly, I put the switch into the faceplate upside down and these new switches are so tight, it's almost impossible to release again! Maybe I'll just have to live with that...

    One thing I noticed was that when switching the amp off (either with or without standby first), there is a loud popping noise over the speaker. I'm not sure if that's new as this amp is not my regular amp. Is it possible at all that this could be anything to do with my work? Read in another thread that it can be due to the cap on the standby switch being faulty, or worse, the filter caps (which I've just changed on my '73 JMP and don' t fancy doing again so soon!)
     
  9. South Park

    South Park Well-Known Member

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    That popping sound is a voltage spike it is not the switch . Check the location of the switch in the power rail . Good call on that switch
     

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