What kind of switch is this?

Discussion in 'Amp Central Station' started by Preacher, Jul 23, 2021.

  1. Preacher

    Preacher Friend of Leo's

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    So I have an old Big K Kustom Mark III bass head that I use for larger areas. It does not get a lot of play as I don't like lugging around 100 pounds of MDF and steel chassis.

    I have some times coming up when we might be playing some outdoor venues and I wanted to make sure that my head was operating properly. So I go to switch it on and the switch part of the switch comes off in my hands.

    IMG_3224.jpg

    You can see the break where the housing meets the threaded insert. I guess since this unit is 30+ years old it got a little fragile.
    So this switch is an on/off/on switch. I have never really wondered why it was an on/off/on switch as I never noticed any difference with it up or down.

    The wiring is top two lugs goes to the lamp which illuminates when the switch is on, the middle two lugs are the hot and neutral from the plug and the bottom two lugs goes to the tranny.

    I swear I ordered an on/off/on switch from Mouser, but today I got a on/off switch. I looked at my order and the switch I ordered was an on/none/on switch which makes no sense as there are only two positions, up or down.

    The switch rating I received is also quite a bit different, it is a 10A -250V / 15A - 125V switch where again I thought I had ordered the same as what I show in the picture.

    So switch gurus, can you tell me what the broken switch is that I have and if the switch that was sent will work even though it is a on/off (I can bypass the lamp for the time being).

    IMG_3225.jpg

    IMG_3223.jpg
     

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  2. Chipss36

    Chipss36 Tele-Holic

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    You have the switch, wire that sucker up man!

    3 throws on off on or two on/off should not matter.

    the switch wiring should be exactly the same as it was. Use a continuity meter to make it do the same exact function.

    only thing different will be two positions rather than 3

    ratings are fine.
     
  3. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    It looks like it was wired to reverse the hot and neutral when switched up vs down.

    *off* is the center.
    *on* is either up or down.


    An *on* *off* switch will work. Wire the hot and neutral to one side. The lamp and tranny to the other.
    It is rated for more power than the original switch. No worries.
     
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  4. guitar_paul1

    guitar_paul1 Tele-Holic

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    Is there a death cap in that amp?
    Does it have a 2 prong wall plug?
    If so, have a tech change the wiring to a 3wire power cord and a 3 prong plug and remove the death cap.
    It looks like that's what is going on.

    Once that is done, a tech could probably use the switch you got.

    Otherwise you could easily wind up with 120v live on the chassis of the amp. Dangerous.
     
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  5. J. Bonkosky

    J. Bonkosky Tele-Holic Silver Supporter

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    I is a double pole double throw switch. DPDT on-off-on. You can get a drop in caroling replacement from digikey or mouser for about $6. Just get the same specs on the switch.
     
  6. Chipss36

    Chipss36 Tele-Holic

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    A kustom is a solid state amp, it has no ground lift, and likewise no “death”. Cap.
    The switch is fine as is.
    Provided it is a dpdt switch. It should have 6 lugs.

     
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  7. wabashslim

    wabashslim Friend of Leo's

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    The original switch is another way of switching ground, instead of the Fender-style separate on-off & ground switches. An outmoded method in today's 3-wire society. So do the 3-wire conversion and have the tech use the switch you bought if at all possible. It looks like a heavier-duty one than the original.
     
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  8. RodeoTex

    RodeoTex Doctor of Teleocity

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    From the OP, I don't understand what is meant by on/off/on versus on/none/on.
    I suspect the original switch might be a DPDT on/on switch maybe.
     
  9. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

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    The original switch is a DPDT on/off/on switch. A DPDT on/off/on switch has a center detent. (three positions). (6 terminals.)

    A DPDT on/none/on switch is a DPDT on/on switch. No difference. (6 terminals.) A DPDT on/on switch can function as a on/off switch but it is more versatile than an on/off switch. It can also be wired to reverse the lines by connecting pin1 with pin6 and pin3 with pin4.

    A DPST on/off switch only has four terminals.

    The OP can wire the new switch to work as a on/off switch, switching the amp and the pilot light *on* at the same time.

    EDIT: corrected DPDT to DPST
     
    Last edited: Jul 24, 2021
  10. Preacher

    Preacher Friend of Leo's

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    It is a solid state amp and has had some modifications but no death cap. Although some of the caps are pretty big and you sure don't want to lick them! You can see the grounded line just behind the caps. I did figure out that the on/off/on switch was used as a reverse polarity option, the switch allowed the polarity to be switched flowing to the tranny. Switch wired up and it is running fine.

    IMG_0625.JPG

    You can see the mod it had when I first got it. Take a look at the fuse circuit... LOL

    IMG_0626.JPG

    Yep that was not to spec, I removed the clips and soldered in the fuse for safeties sake.
     
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  11. guitar_paul1

    guitar_paul1 Tele-Holic

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    Good job! Thanks for the update. Alligator clips - I love it!
     
  12. Preacher

    Preacher Friend of Leo's

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    Yeah it was pretty funny when I opened it up. I bought it from a guy who said it only worked intermittently. After opening it up I figured out why it was only working sometimes as that connection with the electrical tape was not very good.

    As soon as I saw the alligator clips I was like.

    upload_2021-7-24_14-32-20.jpeg
     
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  13. wabashslim

    wabashslim Friend of Leo's

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    No, that would be a DPST.
     
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  14. Chipss36

    Chipss36 Tele-Holic

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    So it running again?
     
  15. Gunny

    Gunny Tele-Holic

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    You can find this type of switch in Peavey amps frequently. On-Off-On for AC line polarity switching.
     
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  16. teleplayr

    teleplayr Tele-Afflicted

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    Exactly!
     
  17. Preacher

    Preacher Friend of Leo's

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    Shaking the walls!!

    Thanks for all the replies. And apparently I wired it up correctly as it is not buzzing!
     
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  18. Chipss36

    Chipss36 Tele-Holic

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    Man that’s as good as it gets bro!
    I tip my hat to you.
     
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