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  • Allen MOS1 Board

    What is the part # convention on these boards? I see some of them with the white labels like A246 etc. but some having them for sale show different longer numbers. Is the paper label a version of a particular part # board?
    Help me get un-confused?
    Thanks!

    John
    Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

  • #2
    The paper label is the "code" of the particular board. All MOS1 main boards are interchangeable for troubleshooting purposes, but the voices may not be correct if the code is not the right one for a given organ.

    The A or B at the beginning means "Advanced" (has the card reader chips installed) or "Basic" (no card reader chips on board).

    The first number (1, 2, or 3) indicates which of the sample sets is installed in the primary memory. (IIRC, there were boards made with the number "8" in this position to indicate they were for the keyboard synthesizer or the digital harpsichord, but very few of these were ever made.)

    The second number (4 or 5) indicates which sample set is installed in the 16/32 memory chip.

    The third number (6 or 7) indicates which set of mixture samples is installed in the mixture memory.

    For example, the original basic church model uses code "B-1-4-6" (without card reader) or "A-1-4-6" with card reader.

    Early in the MOS era, Allen introduced what they called "second church voicing" which was a slightly altered stop list with a few stops swapped into the opposite channel. The code for organs having this voicing is "B-2-4-6" (no card reader) or "A-2-4-6" with the card reader. You can see that the "1" is replaced by a "2" to indicate "second church voicing." If you use one of these boards in an organ built for the original voicing, a few stops will produce the wrong tone, but the organ will otherwise work fine.

    Numerous other variations of codes exist. The number "3" appearing in place of a 1 or 2 indicates theater voicing. The number "7" replacing the 6 indicates higher pitched mixture voices (normally used only on a second computer, so the mixtures could be more complex that the standard set). A number "5" replacing the 4 indicates that some of the 16' and 32' stops are replaced by theater samples, and that the 16' reed on the swell is replaced by a very heavy 16' tibia.

    So the code on the paper label is a vital bit of information, though in many cases it might not be crucial, if you just need a MOS board to make an organ work that is otherwise dead. Just know that it won't necessarily produce the tones that are on the stop tabs if the code is wrong.

    BTW, sometimes you will see some extra letters at the end of a code, such as "FS" or "SP" and possibly others. These indicate that certain options are installed on the board. FS = "frequency separation" (a slight difference in tuning of the two channels) and SP = "slow pedal" (an intentional delay in the speech of pedal stops, implemented on large multiple computer models to emulate the lag in speech of certain pedal pipes; SP is used only on one of the two computers in a doubled organ, otherwise the pedals would be really slow to the point of being annoying).
    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

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    • #3
      Great info. I still have a few MOS1 boards from a 123 model that I will be happy to give anyone who will pay for the shipping. The mother board is not among them. Also have a card reader and a few other parts. Again, free to anyone who will pay the shipping.

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      • #4
        Hi,

        Does Allen still take MOS -1 boards back?

        I know for a long time they gave a credit to dealers/ technicians for boards sent back for inventory, repair etc.

        Can't imagine there being much call for them these days, since most MOS-1 stuff being over 40 years old, and hopelessly out of date.

        AV

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        • #5
          I don't know if Allen will pay anything for MOS boards or not. They will certainly charge a LOT less for exchange of a board for an identical replacement, than for the outright purchase of a board. But other than exchange credit, I don't know that they offer anything for old boards. Could be the case and I just don't know about it. Many many years ago they did let me send them several unneeded T-50 amplifiers, and they gave me $25 each for them I think.
          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


          • #6
            which boards do you have?

            - - - Updated - - -

            you’re just an amazing wealth of information, thanks.
            Can't play an note but love all things "organ" Responsible for 2/10 Wurli pipe organ, Allen 3160(wife's), Allen LL324, Allen GW319EX, ADC4600, many others. E-organ shop to fund free organ lessons for kids.

            Comment


            • #7
              Right now I have a couple of spare A-1-4-6 boards I think, but they both have defects. I just use them for troubleshooting and for temporary replacements when a customer's MOS board has to be sent in for exchange.

              If I were to see an A-1-4-6 or an A-2-4-6 for sale cheap, and could be sure that it works perfectly, I'd grab it up. These are the two most commonly found boards, probably 90% of all MOS organs use one or the other. The more exotic boards, with a "3" for the first number, or a "5" for the second number or a "7" for the third number, are used only in models that are relatively rare, such as theater models, or large custom organs with exotic mixtures.

              I might also buy a B-1-4-6 or a B-2-4-6, as these are identical to the A versions, except that they lack the card reader function.

              It's just a bit risky buying a MOS board off ebay or from any other online source, as you have no assurance that it will work, or that it doesn't have some problems. A guy selling a MOS board for a hundred dollars has probably not gone to the trouble to test it.
              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
                Ok we're verging onto what should be handled via private messaging and items available that should be in the Classifieds, not in the discussion part of the Forum.
                I'm closing this thread and will delete the post with the pictures of the items being offered with the expectation that they'll appear in the Classifieds where they belong.
                -Admin

                Allen 965
                Zuma Group Midi Keyboard Encoder
                Zuma Group DM Midi Stop Controller
                Hauptwerk 4.2

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