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Canadian Silver Jubilee

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  • Canadian Silver Jubilee

    Aside from some cool red stenciling on the back and a funky power switch,
    the Canadian version of this 2550 I got has a different bias set up.

    It pulls AC from the power trans AFTER the standby switch, and through an AC cap, not a resistor.

    I was going to wire it from before the standby, so bias voltage is present before getting slammed with HV DC, however the is no voltage present (?)
    Like AC voltage is there, but when connected to the bias supply, there is no voltage until standby switch is switched.
    Odd.

    The other side of the PT has voltage, but it is higher than the side the bias is tapped from.

    I don't know if this is the same power trans as other versions
    Attached Files

  • #2
    You show us the schematic of what you intend to make it into? How about the schematic of what it is before.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      The rectifier and smoothing for the bias voltage is separate. All you will get from your schematic on point C is AC and lots of it!
      The Bias voltage is on all of the time.
      Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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      • #4
        Originally posted by Jon Snell View Post
        The rectifier and smoothing for the bias voltage is separate. All you will get from your schematic on point C is AC and lots of it!
        The Bias voltage is on all of the time.


        Not on this Canadian version.
        Bias is taken from one of the PT HV AC terminals AFTER the standby switch.

        Bias is NOT on all the time.

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        • #5

          I know the schematic you posted shows the switch operating the HT only!
          Please only post relevant schematics. Thank you.
          Support for Fender, Marshall, Mesa, VOX and many more. https://jonsnell.co.uk

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          • #6
            I would if a had a Canadian version, I was posting that as a reference.

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            • #7
              Sounds like maybe your unit has no ground reference for HT til standby switched?
              Maybe have a look at some JCM900 schematics to see how it compares?
              "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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