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C3 Keyboard Issues. Any theories?

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  • C3 Keyboard Issues. Any theories?

    This C3, NO foam was brought to me with keyboard issues. Look at the video.
    Note that the only issues are with DB#1 and DB#8.
    ALL other DB gave tones on all keys on both manuals.
    I checked the preset panel before removing the keyboard, and could detect nothing abnormal; no crossed or shorting wires, all the screws were snug, etc.

    I have seen this problem before, only that one was a single contact that was stuck under the affected buss bar which, in effect, made a connection with that particular DB.

    Since I made the video I removed the keyboard. Nothing unusual on the TG upon visual inspection.
    I will remove all the keys and the top keyboard cover to see if there are any stuck contacts.
    Then I will remove the buss bars for closer inspection. I do not want to remove buss bars first because I want to see if there is a contact stuck on the wrong side of the BB.

    I would be interested in any theories as to what the problems could be.
    Hopefully I will be able to pinpoint the issue and repairs are not too involved.

    In any case, I will let you all know what I find. Perhaps this will be a teachable moment for us all.

    https://www.youtube.com/watch?v=jsTOkCid_s8

    Here is a picture of that previous keyboard. Note that the contact in the center of the picture somehow got pushed to the wrong side of the bussbar, which shorted it out.
    I cannot fathom how this happened. Even pounding on the keyboard would not do this.
    The only rational explaination that I can come up with is that that key was depressed when that particular buss bar was removed and replaced.
    You may only view thumbnails in this gallery. This gallery has 1 photos.
    In theory, there is no difference between theory and reality.
    In reality, there is.
    '54 C-2 & Pair of 122 Leslies
    H-324/Series 10 TC
    '35 Model A (Serial# 41) with a 21H
    Look at some of my rescues:
    https://www.flickr.com/photos/58226398@N03/albums

  • #2
    I took the keyboard out and apart.
    The DB and everything in it looked pretty good, actually. I have certainly seen worse. There were a half dozen contacts that had the resistance wire broken and hanging. I do not know if this caused any of my issues, though. I will replace them with resistors.

    I did take only one buss bar out so far, the one that corresponds to DB#8, and although pretty worn, the palladiun wire is intact for this one at least. I will take the others out tomorrow.

    The preset panel had been modified from original. I need to look more closely at this to make sure that there is nothing loose.

    This is a video of what I found to be the cause of the constant tone. It was actually easily fixed after I saw how it is all put together.



    Further reports to follow as I dive deeper into the bowels of this machine.

    Bob
    In theory, there is no difference between theory and reality.
    In reality, there is.
    '54 C-2 & Pair of 122 Leslies
    H-324/Series 10 TC
    '35 Model A (Serial# 41) with a 21H
    Look at some of my rescues:
    https://www.flickr.com/photos/58226398@N03/albums

    Comment


    • #3
      I don't know how a mis-wired or loose preset panel would cause this symptoms. As the problem occurs with only one key, and one note of one drawbar on that key is always making contact, and another drawbar at that key is dead, it would seem there is a key contact stuck underneath its bus bar, and perhaps some trauma has occurred with a nearby key contact as a result, causing the dead contact (i.e. bent contact, not inserted all the way, something to that nature.)

      Comment


      • #4
        Watch the above video #2.
        See the offending contact and how I fixed it.
        That was the upper manual, I am just before taking the lower apart to see if there are any more misplaced contacts.

        Bob
        In theory, there is no difference between theory and reality.
        In reality, there is.
        '54 C-2 & Pair of 122 Leslies
        H-324/Series 10 TC
        '35 Model A (Serial# 41) with a 21H
        Look at some of my rescues:
        https://www.flickr.com/photos/58226398@N03/albums

        Comment


        • #5
          Sorry Bob, you're incredibly thorough as usual. Not sure how I missed video #2.
          Was there a burr on the phenolic piece that caused the snag? I wonder if extremely hard playing could have triggered the problem. Interesting.

          Comment


          • #6
            Do you think the keeper is the culprit? Hammond quit using them in 1964.

            Jim

            Comment


            • Bobmann
              Bobmann commented
              Editing a comment
              That phenolic piece was definately the culprit. When I pushed it back with my tool, the contacts snapped back just like is shown in the video.
              Unfortunately, I cannot see that part of the keeper to see if it may have a rough spot or burr. The keyboard in the video was a scrapped one so I could take it apart to the point that I could see what was going on.
              This organ is from the late 50's. I found a US postage stamp inside the keyboard dated 1958 that confirms the approximate age.

          • #7
            Geoff Williamson reported this problem last year. Lachey Doley kept triggering it with keys near CX. It is a problem with the early phenolic keepers. I forget what his workaround was.

            Comment

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