Removing 120V/220V switch on transformer

Discussion in 'DIY' started by Bassblaster, Jun 17, 2017.

  1. Bassblaster

    Bassblaster Super Member

    Messages:
    1,750
    Location:
    Cambridge, Ohio
    i have a pulled transformer from an old shelf stereo system with a multi voltage switch i want to remove. im using this transformer for my LM317 supply and see no need for this switch.
    IMG_0565[1].JPG
    i THINK what i need to so is get the brown and keep it to the black and the blue to the white. the switch is on the side of the white when set to 120V
     
  2. elnaldo

    elnaldo Addicted Member

    Messages:
    6,542
    Location:
    Buenos Aires GMT-3
    I agree, if the sliding switch is moved to the white when set at 120V. It connects the blue to the white, leaving the red unused.

    Check with a voltmeter after yo do the change , just in case.
     
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  3. whoaru99

    whoaru99 Epic Member

    Messages:
    38,567
    Location:
    LoTL
    Yeah, usually slide switch contact is same end as the switch position.

    You can confirm by checking the resistance with power unplugged/not connected. Put the switch in the 120V position then measure between the blue and white and between the blue and red. The contacts that are made/closed should show very low resistance/short circuit and the other one high resistance/open circuit. You'd connect the wires from the terminals that showed low resistance/short between them in the 120V position.

    Also bear in mind during use the other wire probably will still be hot, so be sure it is taped up good or otherwise insulated.
     
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  4. Bassblaster

    Bassblaster Super Member

    Messages:
    1,750
    Location:
    Cambridge, Ohio
    Yep, blue to white was right. love when i can fix things that this is a minute. ill keep that switch, maybe i can use it for something.
     
  5. elnaldo

    elnaldo Addicted Member

    Messages:
    6,542
    Location:
    Buenos Aires GMT-3
    :thumbsup: Easy fix :thumbsup:

    If you ever reuse that transformer, remember that connecting the 220V wire to a 110V line will give you half of the voltage at the output.
     

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