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Conn 716 with intermittent problems

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  • Conn 716 with intermittent problems

    I’ve got a Conn Artist 716 with some intermittent issues. I think they are all related to keying cards but not sure. Any help would be greatly appreciated. Here is what’s going on:

    FLUTE VOICES

    1. On the 8’ flutes (all) the C# - F# in the octave above middle C do not sound. This is true for Swell, Great, and Pedal flute stops in 4’ and 2’ pitches as well in the respective octave.

    2. Alll flutes will couple to the pedal from the Swell and Great EXCEPT the 4’ flute on the Swell.

    3. On the top octave of the Great the 8’ flute will sound softly when the 4’ and or 2’ flutes are drawn without the 8’ flute engaged.


    PULSE VOICES

    1. All pulse voices on the Swell are soft but the great are normal volume.

    2. The middle G to octave C do not sound on both Swell and Great.

    3. The C# in the octave above middle C will sound with varying volume (crescendo and decrescendo).

    4. When the pulse voices are drawn there is a soft A flat below middle C cipher.

    5. There is an “all note” cipher in the middle and top octaves of the Great when a note is released. This cipher is very brief. I’ve included a video of this unusual issue: https://youtu.be/tqAsu615l8M
    Last edited by bowdidge; 06-01-2018, 09:25 PM.

  • #2
    You can search the forum for various comments on the Conn models from that era with digital keying. While Conn's leap into digital control yielded tremendous advantages in the flexibility and authenticity of their organs, the system was soon plagued with troubles.

    In brief, it seems that the soldering to the motherboards of the sockets for those stand-up keyer boards was not done in such a way as to endure the stresses on the joints. That is problem #1 and the most likely cause of all your issues. The cure is painful but usually successful. You have to dismantle the entire keying apparatus (the rows of motherboards with the small daughter cards on the shelf beneath the keyboards). Then you turn the motherboards upside down and re-flow all the solder joints that bear stress. You will see that some or many of them have little hairline cracks, may look like circles around the pins that pierce the motherboard.

    Using a good soldering iron of appropriate temperature, and adequate lead/tin/rosin core solder, rebuild the boards so they will be sturdy enough to hold up those cards without cracking.

    Then, as you re-assemble, use the Vaseline method to coat every spot where metal must pass electrons to metal. In other words, on all the card-edge connectors, on all the little jumpers that go between boards and assemblies. This will address problem #2 in this design, which is faulty interconnection of the various sub-assemblies. As always, use only the thinnest possible film of Vaseline. You want to ease insertion of the cards, let the clips slide on securely to the pins. You want to prevent future corrosion. But you don't want to leave a greasy mess. A little dab'll do ya.

    To be honest, I have occasionally tried re-working one of these and had to give up, never fully restoring all the functions and notes. But more often than not, I've found that the organs become stable and reliable for many years once this process is carried out.

    This is something that a diligent tech can do in a day. Anyone can do it, but it may take far longer if you are not experienced in soldering. And you must be absolutely sure that you document everything. Take pictures, make drawings, make notes, shoot videos. You want to be sure that you can put it back together the way it was when you are done.

    Don't forget to tune the oscillators when you're done, and to check the pitch of the celeste generator (not a note by note system, so you have to set it about 10 cents sharp and let it go at that). The pedals are separately tuned as well.

    Good luck!
    John
    ----------
    *** Please post your questions about technical service or repair matters ON THE FORUM. Do not send your questions to me or another member by private message. Information shared is for the benefit of the entire organ community, but other folks will not be helped by information we exchange in private messages!

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