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  • Allen MDC schem needed

    Can anyone lend/send me a copy of the Allen 081-7031 schematic for the MDC main board, 904-5665 ? Trying to figure out the keying/stop connections for this, before I acquire the board. ( I'm well aware of the limitations of the MDC's :-) ) TIA for any help.

  • #2
    If you are able to get this, I sure would like a copy.
    Mike

    My home organ is a circa 1990 Galanti Praeludium III, with Wicks/Viscount CM-100 module supplying extra voices. I also have an Allen MDS Theatre II (princess pedalboard!) with an MDS II MIDI Expander.

    Comment


    • beel m
      beel m commented
      Editing a comment
      OK! Not sure how much info is on the data sheet I asked about...

  • #3
    To my knowledge, there isn't a schematic available for the MDC main boards. And sadly, there isn't a whole lot of information left on the tech site about the MDC models. I do have a service manual, and might have a diagram of some kind in there that would help. What model is the organ? As you may know, there were at least two types of main boards used in the MDC series over their lifetime. If I have one that is useful to you I can send you a scan.
    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!

    https://www.facebook.com/pages/Birds...97551893588434

    Comment


    • beel m
      beel m commented
      Editing a comment
      John, I sent you a PM to avoid possibly a lot of bandwidth back and forth. If you come up with something I'll pass it on to m&m's if that's OK with you. Thanks

  • #4
    Sorry to be out of the loop right now. And elderly family member passed away this week, and the out of town funeral is next week. On top of that, there is a LOT of stuff to get ready for Holy Week at church, family coming in to visit next weekend, not to mention a few service calls that can't wait! I think you all know what I'm talking about. As soon as Easter is behind us, I'll dig through the MDC manuals and see if I have a diagram that might help.
    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!

    https://www.facebook.com/pages/Birds...97551893588434

    Comment


    • beel m
      beel m commented
      Editing a comment
      Thanks so much. Sorry about your loss. It sounds like your cup is overflowing with activities; I hope you get a chance to relax after Easter :-)

    • jbird604
      jbird604 commented
      Editing a comment
      Thanks! Just post here on this thread again after Easter and I will see it and be reminded. The MDC manual is just down at the shop, just not here at home where I'm doing all my prep work and practice.

  • #5
    jbird604, taking you up on your offer, hoping your schedule has quieted down a bit.
    What I got was: (the other MDC board was sold to someone else)
    MADC Allen Organ Board MDC2 421-2704C 904-5665 081-7031
    Any help with diagrams on the keying and stop connections will be much appreciated! TIA
    Bill

    Comment


    • #6
      Bill,

      Yes, things are settling down somewhat, now that Easter is behind us. Just about wore me out before it was over, but I'm recovering. I was in the shop the other day and noticed that the MDC manual is still on the shelf. I'll take a look at it tomorrow and see if there is anything useful.

      The Allen tech site only shows that the MDC-2 board was used in the MDC-42 and -52, the largest and only AGO models of the MDC series. The MDC-2 is not radically different from the MDC-1 board, but it does have a couple more stops and perhaps some other slight changes. The two boards are not interchangeable though. I found a couple of things on the site that might be helpful to you in figuring it out. Here are PDF's that you might look at while I'm searching for more drawings.

      One of these is the stop wiring diagram for the 42/52 and shows the stops going to J95 on the MDC board. The other is the keyboard wiring diagram (and it is marked as being for the MDC-20 and -30, but other MDC models probably used identical keyboard connections), and it shows the keyboard wires also going to J95.

      It looks like all stop and keying lines go to J95 and are internally linked to J96, which connects to the Preset Board and some other external parts.

      Here are the files:

      mdc42-stop-wiring.pdf

      MDC-keyboard-wiring.pdf
      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!

      https://www.facebook.com/pages/Birds...97551893588434

      Comment


      • beel m
        beel m commented
        Editing a comment
        Thanks a bunch!

    • #7
      There is literally nothing more in the service manual than the two diagrams I shared. Documents on the MDC series were limited and obscure.
      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!

      https://www.facebook.com/pages/Birds...97551893588434

      Comment


      • #8
        Thanks, John, and sorry to hear that. By any chance would you know the connections on P175 and P176? P176 has 4 pins and only pin 3 seems to be connected. P175 has 6 pins and all seem to be connected. Again, this is on the MDC-2 board.
        R, Bill

        Comment


        • #9
          Here's a pic of the power supply connection chart. It shows J175 and J176 to be voltages from the power supplies to the MDC board.
          Click image for larger version

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          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!

          https://www.facebook.com/pages/Birds...97551893588434

          Comment


          • beel m
            beel m commented
            Editing a comment
            Many thanks!
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