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  • Johannus organ sound problem

    Hi everyone,

    I have a 1990s Johannus organ, model Opus CH50. I can't find much about this model on the internet.

    Lately, I have been experiencing some sound problems, almost like electric surging or pulsing. I can hear the pulsing sound very slightly even when no stops are selected. It is an intermittent problem and I can't figure out what might be causing it. :'(

    The lights on the stops will flicker when I am experiencing the problem. It is plugged into a regular household outlet that is not on a dedicated line. I also hear a bit of a hum when I turn on the organ. I bought it second-hand and set up 3 of the external speakers myself, it came with 11.

    Can anyone help me out? Thank you in advance!

  • #2
    Scott,

    Welcome to the Forum. I hope this is only the beginning of your contributions here.

    There was another thread similar to this post, and I can't help wondering if the two are related: http://www.organforum.com/forums/showthread.php?36264 Does your ceiling fan have a light? Other than that possibility, I'll defer to the most knowledgeable techs on this Forum to respond to your post.

    I hope this gives you a start.

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

    Comment


    • #3
      Always troubleshoot the power supplies first. That's about the #1 thing I've learned in 40 years of service work, and it's the #1 thing that I FORGET to do when I jump into a job!

      So before you go any further, you have to figure out what the power supply voltages are supposed to be, what pins or connectors the various voltages are on, coming out of the power supply. Then use a voltmeter to verify that the voltages are (1) very close to the specified level, and (2) that DC voltages are free of AC ripple. Any voltage that is off by more than a half volt or so could indicate a bad rectifier diode, filter capacitor, power resistor in the circuit, transistor in the voltage regulator, or a faulty voltage regulator IC, if it uses those. AC ripple of more than a few thousandths of a volt on any DC line will suggest a bad diode or, more likely, a dried-out filter capacitor. Since these capacitors generally go WAY off spec when they dry out, you may well have a volt or more of ripple on a DC line if there is a truly bad cap.

      Also, with this surging and blinking going on, I have to wonder if one of the voltages comes and goes, perhaps due to a loose connector or a failing component in the leg of the supply that makes it. You might be able to find a loose connector by poking around on the power supply board and associated parts. WARNING!!! There may be dangerous voltages in the power supply. Wear insulating gloves and use something like a wooden dowel to wiggle components while the organ is powered up.

      BTW, most organs built in the past 30 years don't use dangerously high voltages. Most transistor and IC circuitry runs on 5, 12, or 15 volts, with some older stuff requiring 27 volts. These are not shocking voltages. But power amps may actually need 80 volts in the power output section (the old Rodgers S-100 amp did), and you don't want to touch that. So better safe than sorry.

      Of course, as with all older organs, you have to look everywhere in there for loose connections, for plastic plugs not fully mated, for card-edge connectors that have become dirty or unseated, for solder joints that may have failed, screw terminals or screwed-down spade lugs not tight and secure.

      So, in general, you ought to be able to make it work once you take care of all the routine checks and maintenance. But do start with the power supply, at least after you've done a cursory check of all the connections in the system.

      Good luck!
      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


      • #4
        Originally posted by jbird604 View Post
        So, in general, you ought to be able to make it work once you take care of all the routine checks and maintenance. But do start with the power supply, at least after you've done a cursory check of all the connections in the system.
        See, I told you we had knowledgeable techs on this Forum. John's advice is much better than mine, though not as simple.

        Again, welcome to the Forum. I hope I at least gave you a chuckle!;-)

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

        Comment


        • #5
          Hi,

          I don't seem to have info. on this model, other than it is a Johannus Church organ, from the early to mid 90s. It used the M114 chip for the tone generation.

          The communications protocol between the console controller and the tone generators is done in MIDI.

          So after you have checked out the power supply, try hooking the organ to a computer MIDI monitor, and see is MIDI messages are being sent without keying notes or turning on stops.

          I would suggest you get a set of schematics from the factory. Otherwise you are likely not to get very far in troubleshooting.

          AV

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