Ebay Classic organs

Collapse

Announcement

Collapse
No announcement yet.

Mixture Problems - ALLEN MOS-2 organ.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Mixture Problems - ALLEN MOS-2 organ.

    Hello, i have a problem with my MOS-2 organ: the Mixtures in Swell and Great can not turn off. This Mixtures cannot be turned off, they are always on. The Mixtures on the MOS board an E-Prom chip. The E-prom may be defective? Thanks and Regards.

  • #2
    Praestant,

    It would help if we knew which MOS-2 organ you have. For example, if it's a 705 or above, chances are the Mixtures are controlled by a single board, which could be turned off with a switch. If it is a 505 or lower, that is not a possibility. You can temporarily turn the offending board off, but you will be missing some stops and Celestes.

    If you feel comfortable with it, just find a 2nd MOS-2 board on *Bay (making sure the part numbers match), and it will be inexpensive.

    Hope that helps. Meanwhile, see if you can post your model number.

    Michael
    Way too many organs to list, but I do have 5 Allens:
    • MOS-2 Model 505-B / ADC-4300-DK / ADC-5400 / ADC-6000 (Symphony) / ADC-8000DKC
    • Lowrey Heritage (DSO-1)
    • 9 Pump Organs, 1 Pipe Organ & 6 Pianos

    Comment


    • #3
      What model is your MOS-2? Large MOS-2 models can have a dedicated computer for mixtures.

      Regardless, I doubt that your problem is EPROM related. The EPROM stores the waveform and since you're hearing the mixture stops I think you should begin elsewhere.

      Does the organ have crescendo pedal? If so, check to see if any of the crescendo wires are touching each other or are shorted to the contact bar when the crescendo is closed. Next, look at the stop assembly for the mixture. Make sure that contact is opening up when the stop is off. Next step would be the Stop Array board. Make sure that none of the pins on the connector to the board are touching. If your model has multiples stop array boards, you could try swapping them and see if the problem follows a board.
      -Admin

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

      Comment


      • #4
        Thanks, my Organ is the Allen model 124 m with 1 single computer (MOS-2) board. She has only one swell pedal .

        Comment


        • myorgan
          myorgan commented
          Editing a comment
          Do you have a cat? My MOS-2 had some issues when I first received it, and it was because a cat had been crawling around inside the console and caused a couple of pins to contact each other–either through a stray cat hair, or bent pins.

          Michale

      • #5
        I don´t have a cat. The problem affects both mixtures in Sewll and Great . Therefore , a problem with the connection wires can be ruled out, i think so.

        Comment


        • #6
          To those more knowledgeable than I: Does the crescendo pedal normally bring in the Mixture regardless of Swell/Great Settings?
          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
            Hello John, Yes it does.

            Comment


            • myorgan
              myorgan commented
              Editing a comment
              In that case, check the Crescendo roller pins to see if any are crossed.

              Michael

          • #8
            O sorry, that was a misunderstanding. My organ has no crescendo pedal. Only one volume pedal. This affects the whole organ, Swell, Great and Pedal.

            Comment


            • myorgan
              myorgan commented
              Editing a comment
              Have you checked the pins on the various cards to see if any are touching each other? I know I mentioned/blamed a cat, but a careless person inside the console can cause the same damage. While you check that, I'll check my MOS-2 manual for the specific cards to check.

              Michael

          • #9
            The 124 uses a solid-state preset board in conjunction with the five blind pistons. I'd find that board and pull the connectors off it to see if there is a shorted diode or something on that board. I can't think of anything else, other than a defective MOS2 board or a bent switch leaf on the tab, that would make the mixtures stick on all the time. The mixtures are not activated through the Keyboard Array like most other stops.
            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


            • #10
              Thanks, the stop board could be defective? The mixtures are activated by the stop board? The stop tabs are ok.

              Comment


              • myorgan
                myorgan commented
                Editing a comment
                Praestant,

                That could be possible, but upon checking the manual, I've found this. If you open the back of the organ, then swing open the door where the MOS-2 & DAC boards are located, the Stop Board Array (SBA) will be the top of the two boards mounted on the back of the panel. Check the long pins (I believe it's on J-159) to make sure none are touching each other, or wired together (also connection J160).

                The Pedal Mixtur II is J159–pin 29. The Swell Mixtur III is J160–pin 7, and the Great Mixtur IV is J160–pin 2. The manual Mixtures come from the EProm, but the Pedal Mixtur II does not. None of the Presets contain a Mixture (unless it is customized).

                Hope that helps.

                Michael

                P.S. Techs on the Forum. Will the organ work WITHOUT the Mixture EProm socketed? Is it possible to remove it to see if that affects the sound?
                Last edited by myorgan; 07-12-2020, 05:46 PM. Reason: Add P.S.

              • jbird604
                jbird604 commented
                Editing a comment
                Yes. The mixture EPROM can be removed and the board will work, just without the added mixture ranks and any other customization that might be on the EPROM. But nearly all the stops should work. That won't fix anything, but it would make the organ playable. I really doubt that the EPROM itself is bad, as that almost never happens, and wouldn't result in an always-on stop anyway. Something is holding the input pin assigned to the mixture stops at ground, either on the SBA or the stop rail, if the mixtures are not wired to the preset board, as Michael has discovered.

                I have had at least one MOS2 board go bad with that very symptom -- mixtures won't turn off. If the tabs are opening and closing correctly and there are no bent pins on the SBA, then the MOS board could well be bad. Fortunately, MOS2 boards do not come in a large variety of "codes" the way MOS1 boards do. There are only two types -- the classical and the theater. The code is marked on the board somewhere. Getting another board with the same code might work, but of course that might not be the problem.

              • myorgan
                myorgan commented
                Editing a comment
                According to my notes, the MOS-2 Board for that organ is #904-5627.

                Michael

            • #11
              Hello, all connection on the stop board Array are correct, thank you. I think it could be the MOS board. ---- On the Keyboardarray there is an IC with 40 pins (DIL 40). This IC has the number: S-151; SMC 8244.This IC was defective and the cause of dead keybords of the entire organ. After the IC has been replaced all keyboard work. Where can i find a replacement for this IC or an alternative? Thanks.

              Comment


              • jbird604
                jbird604 commented
                Editing a comment
                S-151 is the "frequency table" IC. Simply a ROM with the standard list of frequencies for all the notes of the scale. This is a custom IC available only from Allen, AFAIK. But it's not likely to have anything to do with your problem. I've had to replace that chip a couple times, but only when it failed and made the organ completely dead. Has nothing to do with stops being on or off.

            • #12
              Thanks, yes, the defective IC S-151 was a keyboard array problem. I wrote this problem in a other post. I replaced this IC and now all keyboards work again. Now i just have the problem with the Mixtures. I will call our technician. He can test all boards with a second set.

              Comment


              • #13
                Thank. But it is difficult to get a used MOS-2 board.

                Comment


                • myorgan
                  myorgan commented
                  Editing a comment
                  Try *Bay in the US.

                  Michael

              • #14
                Just another thought, does that model have settable pistons?(Sorry if that's been clarified elsewhere) What if a piston had been used to store a mixture setting and is still "stuck ON"? Would it get re-programmed every time?
                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


                • myorgan
                  myorgan commented
                  Editing a comment
                  Originally posted by jbird604 View Post
                  The 124 uses a solid-state preset board in conjunction with the five blind pistons.
                  [snip]
                  The mixtures are not activated through the Keyboard Array like most other stops.
                  John (V.),

                  The 124 has presets, but the 125 has settable pistons. There are a couple of other differences between the two models, but nothing that should affect Praestant's problem.

                  Michael

                • jbird604
                  jbird604 commented
                  Editing a comment
                  It's hard for me to keep up with who has what these days! We should encourage everybody to list their organ model(s) in their signature for quick reference. After all this discussion, I'm leaning toward this being a bad MOS board, especially since I've had that very same issue with both MOS1 and MOS2 boards. Not sure that there is any common reason for this, but EPROM stops do operate differently from the ROM stops. I don't see where he has yet tried just removing the EPROM in the mixture socket to see if that kills them. At least the organ could be played if that does silence the mixtures.

              • #15
                Like John , i suspekt that the MOS2 board has a defekt. In an earlier post i had problems with the Stopboard array; all stops of the swell and great( but not in Pedal) did not let them switch on / off. Now, i have a new replacement stpoboard, that works very well. I have measured and compared the defective and the new board with the Ohmmeter and found 9 defective resistors (all 47k ohm) at the pins on the defective board ( 0 Ohm for the defective resistors. )

                Comment


                • myorgan
                  myorgan commented
                  Editing a comment
                  Praestant,

                  Is it within your skillset to replace the resistors? It sounds like you know what you're doing. Of course, replacing them probably won't pinpoint the cause, but it may provide you with a functional organ–temporarily, at least!

                  Michael
              Working...
              X