Class 5 Power Tube Heat

Discussion in 'The Workbench' started by willyh, Sep 22, 2020.

  1. willyh

    willyh Active Member

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    I Just purchased Class 5 Head and Replaced Stock tubes with Vintage Glass. The PreAmp tubes came right out of the tube dampener But the power tube had melted rubber and was stuck. Is this normal? When I tried different Power tubes they seemed to get real hot right away. Head sounds great and does not apear to have any issues.
     
  2. Matthews Guitars

    Matthews Guitars Well-Known Member

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    Does the plate structure glow dull red when the amp has been on for a few minutes and you turn the room lights off? It should not. A glowing plate means the bias needs to be reset.
     
  3. willyh

    willyh Active Member

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    I will check
     
  4. South Park

    South Park Well-Known Member

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    The bias could be to high or the coupler caps are bad . The bias filter caps could be leaking .
     
  5. willyh

    willyh Active Member

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    power tube looks about the same as preamp tubes as far as "glow"
     
  6. Gunner64

    Gunner64 Well-Known Member Gold Supporting Member

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    They run hot, class A amp perhaps? and The bias is Non adjustable. If yours isn't redplating it's probably running as intended.

    The old boys used to call the 6bq5/El84 tube 6 barb-b-q 5 as they always ran hot.
     
  7. willyh

    willyh Active Member

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    Yes that is what I found out. They make tube coolers that Hi Fi guys use. drops Temperature over 100 degrees. going to get one and take off damper on EL 84
     

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