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Rodgers 890 repair adventure

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  • Rodgers 890 repair adventure

    No doubt I blabber too much about my organ issues -- my first distressing but now exciting experiences with the Yamaha HX-1 at home, the poor but serviceable Galanti I'm playing in church, and the wishful thinking I've been doing the past few months about getting a better organ in both locations. But in what other setting can one talk about his "organs" and have people actually understand and sympathize?

    So, bear with me, if you will, as I make a few comments about developments in these areas.

    After months of waiting, I finally got that Rodgers 890 I've been wanting brought into the shop this week. The church it came from purchased a new Trillium model about 10 years ago and kept this 890 in a secondary auditorium, but found they never used it. So when they eventually realized that they had bought way too little audio with the Trillium, and we convinced them to let us do an upgrade, they asked about trading in the 890 on the upgrade. We gladly made an allowance for it and now have it on the way to restoration.

    ..... [It's another story entirely, but this 1700-seat church had been sold a Rodgers T-967 with nothing but the bare minimum speakers in the main array -- six FR1.7 boxes for the manuals plus two SW7.5 units for the pedals. Barely usable, and painfully lacking in bass and body. It did have a substantial antiphonal, but pretty useless in the fan-shaped room. We're beefing up the main array with double amplification and quadruple speakers. For subs, we're putting in four renovated P32 cabinets (each one driven by its own amp) instead of the wimpy SW7.5 subs it came with. Gonna be a pretty awesome organ once this is done!] ......

    Anyway, back to the 890. The organist -- a very capable player -- had apparently always hated it, and that's why they got the new organ 10 years ago. Apparently they believed it had un-fixable problems, and I thought it might, until I got to working on it today in the quiet solitude of the shop.

    There was a note that sounded softly all the time in the choir division -- not a cipher, but a "play-along." Whatever stop you'd draw, when playing any note, a high E-flat pitch of the same stop would sound without being played. Obviously made the choir unusable! I rather quickly isolated it to one of the 4094 chips on the choir decoder in the ganging array. Popped in a new chip and cured that problem.

    On the great, the C above middle C would not sound on the 8, 4, or 2 foot principal stops (or the gemshorn, which is the 8' principal softened). Sounded on the mixture and on all the other stops. Obviously not an oscillator or keyer issue because it was three different pitches and those pitches worked in the mixtures and other stops. I finally realized that there is a separate decoder just for the three great principal pitch gates, replaced the offending 4094 on that board, and all is well. It had me buffaloed because I knew the great decoder (I thought there was only one) had to be working for all the rest of the stops to sound on that note. It sure helps to figure out exactly how a particular model works!

    Finally, when playing any swell stop that was drawn from the unit principal -- which included the viola, the 4' principal, the fourniture, and the cymbel -- playing certain "A" keys would cause the adjoining A-sharp to sound, and vice versa. Made it almost impossible to play the swell except for the flutes and reeds because this "run" showed up all over the place when multiple principal stops were drawn.

    I was about to give up and just clip the wires on those two linked pitches, crippling the swell for sure, when I had the idea of tracking down every place where those pitches were connected. The tiny enamel-clad wires that run from one pitch gate to another are generally wrapped around some small pins at the rear of each little board, but at the remotest end of the wire run, which happened to be on the cymbel encoder board, the wires do not "loop" but are simply tied and clipped on the little pins. Well........ I just happened to discover that one of the wires was clipped a little long, and a tiny whisker was sticking out far enough to touch the neighboring pin! It had apparently been there since the organ was built, touching that other pin. I'll bet it had driven them crazy for the past 25 years!

    The only other keying issue was that the celeste portion of the great flute celeste was dead from C4 on up. I dug out the schematic of that keyer board and saw that notes from that pitch on up go through a separate pre-amp, so now I need to troubleshoot that little circuit -- which consists of a transistor and four or five passive components. Shouldn't be too much trouble. It actually clip-leaded around it temporarily and the notes played, so I know I can fix it easily.

    Little wonder that the organist hated this thing all those years. But these awful problems are now banished, and I'm down to the mechanical issues -- a few sticking keys (it has wooden keys and I'm suspecting some have swollen like piano keys do), a few drawknobs that also seem to stick, some burned-out lamps here and there, pedalboard felt and tensioning, and tuning/voicing of course.

    It also came in with a Zimbelstern -- a really nice-looking little unit with a bunch of small ornate brass bells of assorted sizes and types. No two bells are even the same style, some are bell-shaped, others look like over-size jingle bells, or like little decorative bells people put on their whatnot shelves. Unfortunately, the motor is burned out. It looks like a common synchronous shaded-pole motor, like electric clocks used to have, or similar to a Leslie slow motor, but it also has a little enclosed gearbox. Maybe I can find one and get this thing to work. Would be a lovely addition to the organ, and I was looking forward to using it.

    I sat and played the 890 for a while last night, connected only to five of the flat-panel Rodgers speakers and a spare Allen SR-5 subwoofer. It sounds a lot better than I thought it would. I had expected it to sound crude compared to the nice Allen MDS-45 sitting in the same room, but it holds its own quite well. So.... will it wind up in my church to replace the little Galanti? Still haven't approached the church board about that, as they have had their hands full with some facilities and personnel issues lately, but I'll certainly post about that if and when!

    Anyway, my "organ" friends -- that's what's on my mind this morning and I hope it was a little interesting to someone.
    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

  • #2
    The synchronous motor you need is 60 RPM--at least that is what is in my Rodgers Zimbelstern.

    This might work: http://www.herbach.com/Merchant2/mer..._Code=SYNCTIME

    Comment


    • #3
      John - Thanks for this post. I always enjoy a good troubleshooting story.

      Jim
      -----------------------------------------------------------------------------------------------------------
      Keeping (too many) old organs alive.
      Allen ADC 2110-T, Rodgers Trio 321B
      Conn 651, 713
      Hammond M-3 w/Leslie 120
      Hammond Solovox
      Mass-Rowe model 96 Carillon

      Comment


      • #4
        Hi,
        We are currently re-purposing an 890 to be a MIDI controller for a Hauptwerk VPO and have all the boards on the three wooden racks available. Free except you pay the freight and tell me how the On/Off circuit works :). I see how it turns on but not how it turns off. It looks to me that it turns on and is held on by the noise from the air sound board. The real mystery is what all the extra wires on the on/off switch are for? Can you help?

        Thomas

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        • #5
          Thomas,
          I would be every interested in acquiring those boards from the 890.

          I have been trying to figure out what keeps the power supply on. There is a signal to the power supply that comes from one of the circuits on the Air Sound board (which has more than Air Sound on it) but I can't find anywhere what that circuit is. I can tell you that the signal to the power supply must be AC (constantly switching) as opposed to a simple DC level. The main Power Switch is simply connected across the relay contacts so I suppose it is a momentary that powers up the system until whatever-it-is that comes from the Air Sound board starts up. Also, you may have found an "Override Switch" on the power supply; this is wired in parallel with the main power switch and I guess it would be momentary also.

          I don't know how many wires you have on the Power Switch but I did find that there is a 2nd pair that operates the Mute circuits. It's kind of unusual to run low-level signaling to the same switch switching AC.

          I can keep looking, if you like. Since you're gutting the instrument, I would think the only thing you would need to know is how the Power Supply works, though I would have thought that would go also.

          As I said, I am interested in acquiring the boards; send me a Private Message.

          Greg

          Comment


          • #6
            The power switch on this organ involves magic and voodoo and cannot be described in purely technical terms. I know this from long experience!

            JK. I can't describe it without spending an hour digging through the manual, but it involves the CPU and the power supply and a signal referred to as "keep alive" which keeps the relay closed after you let go of the switch. The bypass switch on the power supply simply shorts across the relay contacts, making the keep alive signal unnecessary.

            If you are using the 890 console as a MIDI station, you only need a simple on-off switch anyway, so don't even try to figure it out. It will drive you crazy.
            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


            • #7
              And, you know, John, all that "magic" is simply so that the thing has automatic power-off, a great big "Who cares?" feature, as far as I'm concerned.

              Greg

              Comment


              • #8
                Originally posted by NoTalent View Post
                And, you know, John, all that "magic" is simply so that the thing has automatic power-off, a great big "Who cares?" feature, as far as I'm concerned.

                Greg
                I always thought it was a protection device. Not allowing it to power up if the computer didn't boot properly. Maybe in addition*to that something to do with the pass codes.

                Geo

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