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  • Isolation transformer question

    Hi everybody!

    I recently bought an old AC/DC tube amp (35W4-50C5-12AX7) and I want to add an isolation tranformer.

    Ive read the tutorial posted at instructable.com

    here

    Here is the schematic:

    Click image for larger version

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    As you can see, there is a "chassis ground", and a "line ground" (floating) ...

    Here is my question:

    In order to correct the half wave problem, I should add a bridge rectifier like this:

    Click image for larger version

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    Should I connect the grounds (circled in yellow) to the "chassis ground" or "line ground"

    Thank you!
    Last edited by sparchead; 11-13-2012, 10:51 AM.
    And man created the vacuum tube, and it was good...

  • #2
    The negative terminal of the bridge rectifier should go to "line ground" where the neutral wire of the old line cord used to be.

    The "line ground", as well as the chassis and other exposed metalwork, should then be connected to the green wire of the new line cord. So you can see that "line ground" and "chassis ground" end up the same thing, proper safety ground, which is the whole point of installing the isolation transformer.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

    Comment


    • #3
      Originally posted by Steve Conner View Post
      The negative terminal of the bridge rectifier should go to "line ground" where the neutral wire of the old line cord used to be.

      The "line ground", as well as the chassis and other exposed metalwork, should then be connected to the green wire of the new line cord. So you can see that "line ground" and "chassis ground" end up the same thing, proper safety ground, which is the whole point of installing the isolation transformer.
      thank you very much =)

      Just to be sure... when you say "The line ground, as well as the chassis and other exposed metalwork, should then be connected to the green wire of the new line cord", I understand that, but the "line ground" stays connected to the "chassis ground" through the 100K resistor and .03uF cap, not directly, correct? I mean, I don't have to remove them...
      Last edited by sparchead; 11-13-2012, 11:48 PM.
      And man created the vacuum tube, and it was good...

      Comment

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