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Allen 423-C dead pedal note

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  • Allen 423-C dead pedal note

    I've been super busy with other projects since I did the three upgrades to my Allen 423-C MOS-1 theater organ (posted on January 23rd on the Forum.) But last week I finally had time to push it back against the wall so I could take photos and put it on Craigslist. When I set the pedalboard in place I decided to test all of the notes. Imagine my surprise to find the C#1 pedal not working!

    I took the pedalboard off again, got a magnet and tested the notes that way. I could hear the reed switch clicking for that note but no sound. I looked at the pedal schematic and saw that there was a diode matrix. Having never seen the inside of an Allen pedal reed switch assembly I did not know where the diodes were located. A quick look inside the organ (argh, pulled it out from the wall again) I saw that there were relatively few wires going from the pedal assembly to the keyboard array PC board so they had to be on the reed switch assembly.

    Remembering stories about having to be careful about the vertical alignment of that reed switch assembly after it was taken off, I was pleased to find that there were two additional wood screws, one at each end, that held the whole assembly in place at the right height. But I marked everything anyway before removing the screws. I also undid the twist ties holding the bundle of thin white pedal switch wires inside the organ so they would not be stressed when I removed the reed switch assembly.

    While I stepped away, looking for a tool, one of my weekend house guests was looking at the suspect reed with a flashlight. When I got back he told me he found the problem. The wire on one end of the reed switch had not been soldered properly onto the post and was about 1/32 of an inch away from it. We touched the wire to the post and tested it with a magnet and it worked just fine. So 5 minutes later I had re-soldered the connection and we put everything back in place.

    I have no idea how long this pedal note was not working. I know I tested everything when I bought the organ and again when I moved it to its current location, about 10 years ago. The pop music I play on this instrument rarely uses that note so it could have been years since it stopped working. I'm just glad it was such a simple fix.
    Larry is my name; Allen is an organ brand. Allen RMWTHEA.3 with RMI Electra-Piano; Allen 423-C+Gyro; Britson Opus OEM38; Steinway AR Duo-Art 7' grand piano, Mills Violano Virtuoso with MIDI; Hammond 9812H with roll player; Roland E-200; Mason&Hamlin AR Ampico grand piano, Allen ADC-5300-D with MIDI, Allen MADC-2110.

  • #2

    Thank you for sharing your saga with us. The only two problems I've ever discovered with Allen's pedals are:
    1. When notes at one end or the other don't work properly, due generally to a lost caster; or pedals adjusted for a solid floor subsequently being placed on carpet.
    2. When moving one of the organs, someone helping me (presumably) unknowingly strikes the reed switches on the organ side, breaking 1-3. Good help is so hard to find!
    I'm glad you discovered your problem and posted the solution. Great detective skills, however, I wouldn't have been as daring and removed the reed switch assembly without knowing what I was doing first. Obviously, one needs to remove the assembly in order to replace a defective reed switch, but it is a daring move all the same.

    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)
    • 11 Pump Organs, 1 Pipe Organ & 7 Pianos


    • AllenAnalog
      AllenAnalog commented
      Editing a comment
      Once we saw that there was a wood screw in a round hole at each end of the reed switch assembly securing the vertical position set by the screws in the slotted holes, we knew that there would be no issue getting the assembly back into the correct vertical alignment. With the other work I did on the internals of this instrument (adding a +/- 15VDC power supply for the new DAC4 board and installing a totally new battery backup system), removing the reed switch assembly didn't seem all that daunting.

      I'm not sure if all Allen pedal reed switch assemblies have those two end screws but looking at photos of my ADC-5300, it is made the same way as the 423-C unit.

  • #3
    Great detective work (by your guest!). Wish all pedal keying problems were that simple. I've seen a few Allens in recent years on which a few of the reed switches had apparently deteriorated and would no longer make internal contact, even though you could hear them click when a magnet came near. No choice but to replace them, and of course you must be very careful to line them up properly or else that pedal will key too early or too late relative to the rest.

    Pedal board alignment issues are most often due to (as Michael notes) carpet on the floor or an unlevel floor than to any actual change in the location of the switch rail, which as you note, is securely fastened to the console and normally left in the factory default location (set by the non-adjustable screws at each end which you discovered).

    Now and then we run into a MOS or ADC on which the little notches at the sides where the pedal board attaches to the console have become worn down enough to let the pedal board settle down too far. This can cause pedal ciphers or make all the keys sound too quickly. the cure is to line the little curved notches with a layer of thin self-sticky felt.

    Another pedal issue that can show up, but very rarely, is the packing of the felt up-stop in the pedal board. With organs from many other builders this is a major issue that sometimes appears in consoles less than 10 years old. But with Allen pedals, which use a thick heavy felt up-stop (sourced from OSI, I suppose), the up-stop is far more durable. Most MOS organs still have their original pedal felt, some of them approaching 50 years old!
    *** 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!


    • myorgan
      myorgan commented
      Editing a comment
      Originally posted by jbird604
      Most MOS organs still have their original pedal felt, some of them approaching 50 years old!
      That may also be because Yvonne never played the pedals. ;-)


    • jbird604
      jbird604 commented
      Editing a comment
      Yep. That cousin of mine would've destroyed the felt, at least on the low c, g, and f!!