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Vintage SVT Standby switch HELP!!!

Discussion in 'Amps and Cabs [BG]' started by slap5string, Aug 6, 2012.

  1. I ordered the replacement switch from Fliptops and it looks nothing like the original. The original has 4 prongs / connectors on its top and the wires are bridged across. The new switch has 3 prongs - one on one side / two on the other. Since there are 2 wire to this switch - how do I know which side to connect each wire to?
  2. old switch
  3. new switch
  4. Ok - well, one giant leap of faith and voila! My amp is fixed! Standby works as it should. I was very impressed by the worksmanship of whoever wired this old amp. Pretty cool pc of American history. Still crushing the masses after 40 years!
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I'm not sure which switch you have but it looks like a Carling SPDT two position toggle switch. Below is a schematic of the switch. As you discovered, connect one wire to common, and the other wire to either L1 or L2. Which one isn't important. Connecting to one or the other is the same as rotating the switch 180 degrees.


  6. Well, we actually connected one lead to the single pole on one side and the other lead is bridged across both leads on the other side similar to the way the old switch was wired. So far it is working properly, which I do not understand if the switch works the way the diagram is.

    Basically the white lead is soldered to the "com" and the green lead is soldered to L1 AND L2. Theoretically, this would mean the switch is ALWAYS on, no?
  7. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    It must be a different type of switch than the one I thought you had. Since it works, great!

    On the old switch, it was wired as two switches in parallel. Each half shared the current that way and there was a failsafe in case one side developed a problem.
  8. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I would think so but if it is a different type of switch, it isn't going to work like in the diagram.

    When the standby switch is working, in one position, just the heaters are on, the tubes will glow, but no sound will come out of the amp if you play. In the other position, the heaters will be on and sound will be coming out of the amp when you play. If it is wired wrong, sound will be coming out in both switch positions.
  9. I'm a little concerned :) Is there any inherant danger or damage that could result from this switch being wired wrong? Or will it either work or not?
  10. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I edited my last post above. If it is working properly like in the last paragraph, you are ok.
  11. Ok - I should be good to go. In the "standby" position, the tubes warm-up and glow. When standby is lifted, sound comes from the amp.

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