Help determine which lamps are in the 6100.

Discussion in 'Marshall Amps' started by Pavel125DV, Feb 19, 2020.

  1. ampmadscientist

    ampmadscientist Well-Known Member

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    Are you talking about the lighted power switch?
    Or are you talking about the LED panel lamps?
    Or are you talking about the vacuum tubes which light up?

    I think you are calling the vacuum tubes "lamps," and that makes it sort of confusing?

    If you need to identify which vacuum tubes belong in which version:
    A. You check the value of the screen grid resistors for the output tubes.
    B. You check the bias adjustment circuit resistors.
    C. You check the bias split resistors.

    After you know which resistors are installed: then you will know which output tube belongs in the amplifier.
     
    Last edited: Feb 19, 2020
  2. Pavel125DV

    Pavel125DV New Member

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    I meant EL34 and 5881. Power amplifier tubes.
     
  3. Jethro Rocker

    Jethro Rocker Well-Known Member Premium Member

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    6100 uses multiple 12AX7 in preamp. Has a different arrangement for each channel. It is NOT a solid state amp. Good grief.
     
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  4. ampmadscientist

    ampmadscientist Well-Known Member

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    You check the resistors (output tube) as above.
    The resistors tell you which tubes belong in the amp.
    If you have 470 ohm 5 watt screen grid resistors, the amp was built for 5881.
    The 5881 version has 2X 150K bias split resistors.
    In the 5881 version you will find a 51 volt zener diode in the bias adjust circuit.

    "These amps use 7x ECC83 and 4x EL34 tubes. Originally these amps were fitted with Tesla EL34's, but late 1993 Marshall switched to 5881 tubes. The ECC83's were Chinese."
     
    Last edited: Feb 19, 2020
  5. Nik Henville

    Nik Henville Well-Known Member Premium Member

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  6. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Good to be here mate, but lamps or Pipes yes it does matter when we are talking technical
     
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  7. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Thats all very well if you know the resistor color code. lol
     
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  8. scozz

    scozz Well-Known Member

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    Let me say Mr. Underwood, it is an honor and a privilege to have you as a member of this forum!
     
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  9. Ken Underwood

    Ken Underwood Well-Known Member VIP Member

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    Scoz, and every one else for that matter, please please please call me Ken, not Mr Underwood, thats far to formal.

    I only get called Mr Underwood when i am in trouble lol
     
  10. Chris-in-LA

    Chris-in-LA Well-Known Member

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    Ok, Ken, I definitely hear you and will drop the fawning attitude.
     
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  11. Sir Don

    Sir Don Well-Known Member

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    Good to see you back here Ken, your contributions are valuable.
     
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