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  • Static from PR-40

    Recently my PR-40 has been generating some unwanted static. I noticed that it would often make a little static when it was warming up, but would always go away. However, the last few days it remains for extended periods at seemingly random times. Sometimes it makes no static at all. I have flipped the switches on the reverb/vibrato/percussion and no difference. It remains when I flip the switch to the Leslie as well. No static from Leslie.

    Had the machine running a lot today as we got a bunch of snow, but had to shut it off before supper because of the static. Don't know if that had anything to do with it. I'll try it again later anyway.

    Any thoughts?

    Thanks!

  • #2
    Always check tube sockets/pins first. Cleaning the pins, small wire brush or eraser, and applying some contact cleaner and reinserting into the amp. This fixes the majority of static problems.

    Geo

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    • #3
      When I turned the PR-40 around and fired it up, I noticed that one of the EL84 tubes (stamped with Hammond) was not lighting up (4th one, I believe). Is this the cause of my problem or a symptom of a greater problem?

      If I need to replace it, how would I go about doing that? Do I need to replace all 6?

      Thanks

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      • #4
        Originally posted by 32Pedals View Post
        When I turned the PR-40 around and fired it up, I noticed that one of the EL84 tubes (stamped with Hammond) was not lighting up (4th one, I believe). Is this the cause of my problem or a symptom of a greater problem?

        If I need to replace it, how would I go about doing that? Do I need to replace all 6?
        This is a complicated question, involving a number of judgment calls.

        We can't know how many hours of use are on your EL84 tubes, which were made by Amperex, pretty much the best EL84s ever made, but even they don't last forever.

        Historically, techs have rarely replaced EL84s in PR-40s until they are worn down to nothing. I've seen some that were so worn out that it was amazing that they still produced any sound.

        Assuming you don't have access to a tube tester and that one EL84 is really not lighting up, you could replace the pair in that channel as a matched pair. Each pair is the output stage of one channel.

        One some, when all the tubes are badly worn, I've replaced all six.

        I would check to make sure that one tube isn't lighting up. It can sometimes be hard to see -- or the heater pin may be oxidized.
        I'm David. 'Dave' is someone else's name.

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        • #5
          Originally posted by geoelectro View Post
          Always check tube sockets/pins first. Cleaning the pins, small wire brush or eraser, and applying some contact cleaner and reinserting into the amp. This fixes the majority of static problems.

          Geo
          Sounds like a pin cleaning is in my future. I will keep you updated.

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          • #6
            Cleaned pins and sockets. Static gone. I really appreciate all the help I have received on this forum. Thanks!

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