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Help! Our church's Rodgers 800 is making a 'beehive' sound

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    Help! Our church's Rodgers 800 is making a 'beehive' sound

    Help me Obi Wan Kenobi, you're our only hope.

    Our church doesn't have the cash to pay for a repair to our early 1980s Rodgers 800 Scarborough organ. An organist turned the key on the power switch and got a brztt and puff of smoke. A repair man came out to take a look at it and moved it, and after diagnosing the bad switch, realized his moving it caused another problem once we turned it on.
    Now, we have a sound like all of the keys being pressed down simultaneously - or a swarm of bees. There is one fundamental tone, so that might be a clue.

    In a past life I was an electrical engineer and worked on some sound amplifiers, so I've volunteered to try to fix it before we give it the heave-ho or have lots of bake sales to raise the cash just to get it transported so someone can diagnose what is wrong with it. I wagering that even trying to lift it would probably knock something else loose and cause a worse problem, so I've cracked it open and started poking around.

    Here is a link to my dropbox site with a video of me recording the organ sound. I'm hoping some brilliant old-timer will say -- oh yeah, that is capacitor C42...


    My plan is to start with the output stage and a powered speaker and just work my way back through the schematic to find the source of the problem - probing at different locations until I can at least narrow down what might be the source. Someone on some forum said it might be trouble with an oscillator, but with 137... that's a pretty broad suggestion.

    Any and all help is welcome and dearly appreciated.
    Thanks.
    Ed
    Dropbox is a free service that lets you bring your photos, docs, and videos anywhere and share them easily. Never email yourself a file again!

    #2
    Follow up: I saw this post:
    "Mini Compact that had what sounded like all the keys were being held down. Re-soldered the grounds in PS and replacing 2 caps fixed that. The customer wanted the power cord replaced. In stock form, one side of the power cord goes to a fuse and the other side is switched. Should I rewire to put the fuse and switch on the hot side or leave as is?"
    Which sounds like my problem, so refurbishing the power supply might be stop #1.

    Comment


    • myorgan
      myorgan commented
      Editing a comment
      EPT,

      Welcome to the Forum! Perhaps your best bet is to contact member, Toodles or jbird604. Toodles knows Rodgers organs quite well, and John (jbird604) is a semi-retired technician.

      Let me summon them for you.

      Michael

    #3
    Unfortunately, I don't have the technical manual for the model 800.

    Toodles.

    Comment


    • ept
      ept commented
      Editing a comment
      Thanks Michael. Fortunately I've found one on EBay and it is now in my possession. I am thinking of going through the whole tech procedure and test it from top to bottom while I'm here and have it open.

    #4
    Have you checked to see if the pedalboard just got dislodged? Moving the console might mis-align the pedal magnets with the reed switches and cause all of them to try to sound at once.

    To check for this, pull the pedal board away from the organ. Just lift it near where it attaches to the console to clear it from the hooks, then pull it back a few inches. If the sound stops, you have your problem. Just re-install the pedals and be sure to wiggle from side to side or back and forth a bit if necessary to keep the bees from buzzing.

    Of course it could be any number of other things on a 50 year old organ. But I wouldn't start replacing things and re-soldering willy-nilly. You are likely to do more harm than good. If it's not the pedals, just use gentle hand pressure to poke around on things (there are no shocking voltages inside, as long as you stay away from the power supply and amps. You may well find a spot where you can press gently and stop the noise. That would point you to a bad solder joint or a wire that's come off something.

    Make sure the big 5-pin connectors that run to the amplifiers (if this one uses external amps) are tight. Wiggle and press them tightly in place.
    John
    ----------
    Church: Allen MDS-45 with Allen MIDI-DIVISION-II expander
    Home: Allen Renaissance R-230 with expanded four-channel audio and MIDI-DIVISION-II
    Shop: Bunch of organs in varying conditions, some good, some not...
    Half of an incredible two-man organ service team -- servicing all the major digitals in Arkansas churches
    https://www.facebook.com/pages/Birds...97551893588434

    Comment


    • myorgan
      myorgan commented
      Editing a comment
      Thank you, John & Toodles.

      Michael

    • ept
      ept commented
      Editing a comment
      Hi John,
      Thanks so much for your reply. I had high hopes it would be the source of my problem. After I removed the pedal board, the sound remained. I continued to fuss with the organ, and it had a couple of odd power cycles (described below) and then the noise went away. I'm not sure if there is some sort of 'capacitive' behavior that, once I removed the pedal board, the sound would remain after a few cycles but eventually go away after a couple of power cycles and discharges? Odd.

    #5
    I'm confused about the model. The 800 is an Alexandria, while the Scarborough is a model 750 according to the Rodgers website.

    Other information that would help diagnosing the problem:
    Is the sound affected by the expression pedal?
    Do any tabs affect the sound?
    Are there signs of rodent presence inside?
    td

    p.s. People were asking Rhonda for help long before Obi Wan Kenobi.

    Comment


    • AllenAnalog
      AllenAnalog commented
      Editing a comment
      Oh Dave, you're dating yourself! And besides, Rhonda jilted the guy so no help whatsoever.

    • ept
      ept commented
      Editing a comment
      Thanks Tuscondave - You're correct - It is actually an 800 Alexandria.
      - Is the sound affected by the expression pedal?: The sound remains regardless of how I press the expression pedal. The pedal makes a 'pop' about 1/2 way up, but it sounds like a bad potentiameter (maybe?) to me.
      - No tabs affect the sound. I can hear all of the keys behind it working, I switched all memories etc and it made no difference to the sound.
      - Yes, there's a nice little mouse house next to the power supply.

    #6
    Thank you all so much for your replies - and thank you for summoning John and Toodles, Michael. I didn't want to reply until I'd had a chance to get back into the church and try out some of the advice. I'll reply to thank each of you above, but I'll summarize my 'findings' (and I'll use that term as loosely as possible) here.

    I immediately followed John's advice, as it sounded like the pedal board could be the culprit. After unplugging it and moving it away, the sound still remained - so my hopes of a lightning-strike fix were dashed - but the sound changed a bit (maybe lost a fundamental tonic tone) - so there still might be something related to the pedal board. When I unscrewed and removed the board that sits opposite the pedal board with the magnets wired into it, I noticed that the one white wire (admidst all of the blue ones coming from each pedal 'key' magnet) was detatched from the circuit board of the Timing Sharing- It look like the wire just snapped at the place where the wire was stripped. I am trying to find what this wire is on the schematic, and whether it was truly attached to anything. It would have to be attached to something near the diodes where the other pedal wires come in, near U22 and U23.

    I mentioned above that the problems originated with the key power switch. I think my first inclination here is to 'fix what is wrong first' - so I'll replace the switch. It is a source of all kinds of odd behavior right now. When I first turned the organ on two days ago (after having been powered off and unplugged for a month), it didn't turn on at all until I probed with my voltmeter on the power supply on one of the leslie connectors, heard a pop and power came on.
    When turning it on today, it came on right away - I fiddled with it today, and found that after I turn the power on, turning the key switch off has no effect - which probably isn't terribly surprising.

    After my disappointment with the pedal board, I started messing with the keys and stops. I noticed that the sound isn't like ALL keys are pushed down, but perhaps just the entire octave below middle-C. All of the keys work, and changing Memory banks/stops has no effect. I looked at every cap/inductor/transistor I could find, and don't see any guys bursting or any burnt spots. As I was playing the organ, the keys sounded a little 'hotter' than normal and distorted. At this point of holding a chord down - the organ all of a sudden powered off abruptly by itself and then faded back into life. This happened twice, and after coming back on again - the buzzing sound was gone! (hooray?)

    I'm not quite so daft as to believe this might end my problems. Anyone have ideas for my ghost in the machine?

    I'm going to replace the switch. I know I need to do that. After that, I'll try to figure out if that white wire is truly something necessary or not. At that point, I'll play with the organ daily for a while, see if the noise returns with the pedal board attached. I'd prefer that it doesn't make its re-appearance during Christmas Mass.

    I have a friend who restores vintage guitar amplifiers, so he and I will chop-stick our way through the organ tomorrow to see if we can find anything.
    -----
    Thanks Tuscondave - You're correct - It is actually an 800 Alexandria.
    - Is the sound affected by the expression pedal?: The sound remains regardless of how I press the expression pedal. The pedal makes a 'pop' about 1/2 way up, but it sounds like a bad potentiameter (maybe?) to me.
    - No tabs affect the sound. I can hear all of the keys behind it working, I switched all memories etc and it made no difference to the sound.
    - Yes, there's a nice little mouse house next to the power supply.
    --------
    Hi John,
    Thanks so much for your reply. I had high hopes it would be the source of my problem. After I removed the pedal board, the sound remained. I continued to fuss with the organ, and it had a couple of odd power cycles (described below) and then the noise went away. I'm not sure if there is some sort of 'capacitive' behavior that, once I removed the pedal board, the sound would remain after a few cycles but eventually go away after a couple of power cycles and discharges? Odd.

    In your experience, would going through the whole troubleshooting procedure detailed in the tech manual? Any caveats?

    Thanks again to everyone for their help.

    Comment


      #7
      The presence of the mouse house is unsettling. The little critters can do massive damage in an organ, and sometimes it's not easy to find, much less correct. Their pee and poop are apparently slightly conductive and will make circuit boards go crazy, and the worst effect of course is the destruction they cause with their chewing of the wires and the disintegration of circuit board components due to the corrosive nature of the pee.

      So you may have a very serious problem. The grand cipher that sort of cured itself could be a symptom of some kind of imminent failure of a power supply section or the loss of a connection somewhere.

      Organ troubleshooting ALWAYS begins with the power supplies. Use the schematic to determine what voltages are supposed to be coming out of the supply, and check to be sure these voltages are present and pretty close to spec. Voltage regulation was not a precise art back in the analog days, so you may find them off by a volt or so in places, and that isn't concerning. Check to be sure there isn't much AC ripple riding on any DC voltage, as that would indicate a failing filter capacitor or possibly a leaking rectifier diode.

      If you see any mouse leavings on any circuit board or on any assembly, you must clean that up very thoroughly and carefully. Make sure you don't make the damage worse, but try to scrub it all away before it can do any more damage. Use circuit board cleaner, but make sure it is plastic-safe and be sure to use it with discretion. Wear gloves and masks for your own safety and health, and vacuum up the residue then clean up your vacuum cleaner and throw away the vacuum bag. This stuff can be dangerous to your health.

      As to the white wire that's possibly come off, that could be a real problem, or it could be a red herring. There were sometimes spare wires in a bundle that were never connected to anything, and that could be one. If possible, trace it and see where it came from and where other wires of the same color go. That might give you a clue.

      I've had an old Rodgers analog now and then that seemed to develop a wire break or a short somewhere in one of those big bundles that gets flexed when the panels are swung out from the rear. Moving the panels around would provoke or clear up the problem -- a cipher would stop, a dead stop would suddenly work again, a sour note would come back in tune, that sort of thing. It could be that your organ developed a break or short somewhere in the course of the current troubleshooting and/or repairs.

      The power switch may be NLA, or very expensive if it's the keylock type. We generally just drill out the hole a tiny bit and install a standard snap switch that comes from Lowe's or one of the supply houses. There are numerous round-body power switches rated for 15 amps or more that will do the job, but some fitting is required.

      As with the building and assembling of these old monster organs, fixing them can take massive amounts of time. If you are working for free, then the church can afford you. But sometimes it quickly becomes apparent that the organ has served its purpose and needs to be replaced with something newer. Fortunately, these are good days for finding a good used organ that may not be over 20 years old. (Fortunate for churches needing a replacement organ, but sad for the churches that are giving away their organs and replacing them with a holey-jeans rock and roll band.)
      John
      ----------
      Church: Allen MDS-45 with Allen MIDI-DIVISION-II expander
      Home: Allen Renaissance R-230 with expanded four-channel audio and MIDI-DIVISION-II
      Shop: Bunch of organs in varying conditions, some good, some not...
      Half of an incredible two-man organ service team -- servicing all the major digitals in Arkansas churches
      https://www.facebook.com/pages/Birds...97551893588434

      Comment


      • ept
        ept commented
        Editing a comment
        Thanks so much for your post jbird604!
        So, I vacummed out all of the mouse house- fortunately, the critters confined their activity to around the power supply (nice and toasty, I'd guess) and there wasn't much of a cleanup.

        Before I take the power supply out, I'll go through the schematics as you suggest and check all of the voltages with my voltmeter.

        I've been pretty fortunate with the swing-out boards. I thought they'd be the source of the problem, but no jiggling seems to make any difference, so I'm feeling pretty confident that the power supply is going to make or break me here.

        As it turns out I was able (after digging through all of Ace hardware's switches) to find exactly the proper cam key switch. The friend who was helping me put my odds conservatively at .2% chance of finding one at Ace, but I found one for $25. Coincidentally, I ran into the deacon from our church at Ace - so I'm chalking this one up to divine intervention.

        The white wire is grouped with the blue wires that run to the back of the pedal board. While each blue wire stops at a different note's coil - the white runs the full length to the end. There seemingly could be one spot I could conceive of it attaching. I haven't found where it lives on the schematics - yet.

        I'm working for free, and trying to save Christmas here... I've considered finding alternative organs online, and that may be where I end up - but the big problem is transporting these things. Getting the bad one out and the good one in (without making it into a bad one).

        After fixing the switch and sort of narrowing things down to the power supply, I am feeling better about my chances.

        As always - thanks for your advice and counsel.

      #8
      Some progress - replaced ths switch and this got rid of some of the nuttiness with things powering on/off by themselves. At least I can turn the thing on and off with confidence.

      At this point, the beehive sound seems to be intermittant - and happens very rarely.

      In tapping around, I noticed that one or two of the power supply capacitors make a lot of noise if I tap them - so it is probably likely they are bad.
      I also spotted that the screws that restrained the power supply motherboard were holding the board torqued at an angle. Once I released one of the screws, I got absolutely no sound from the organ at all - just stopped playing - nothing from the keys. Once I put the screw back in, the organ functioned normally.

      So - this is mixed news. I'm hoping that by replacing all of the power supply caps, and then mounting the board in a reasonable fashion, that all my troubles will go away - but I'm afraid there's perhaps a broken/intermittant trace on the board. I'm going to order the capacitors. When they come in, I'll take the board out and look it over and replace the capacitors and then cross my fingers and try again.

      All sound also went away (nothing from the keys) when I stepped upon the crescendo pedal - but I think that was because it jiggled the power supply card.

      Comment


      • jbird604
        jbird604 commented
        Editing a comment
        While you have the circuit board free, be sure to re-flow all the solder joints. That board doesn't have thousands of tiny solder joints like a keyer board would, just a few dozen big ones. But the big joints, especially where a large pin pierces the board, are very susceptible to cracking. I would re-flow the solder and add a bit of extra at every joint on the board. Use a strong light and magnifying glass and you may see small cracks developing around various connection points. That in itself could be the source of your beehive cipher. I suspect that some of the keyer/gate boards work by "snubbing" the incoming tones with a specific voltage. If that snubbing voltage disappears, the gates will all open at once. That's why troubleshooting the power supply is so important.
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