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OPUS 1100 - Repairs

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  • OPUS 1100 - Repairs

    I'm new to this forum and am from Canada.
    I don't have a musical background and thus don't fully understand some of the terms used in pipe or electronic organ discussions. I can read schematics better than musical notation. :) My training is in Electronic Engineering Technology and I am now retired, after working 35 years in the aviation sector.

    My church (in Ontario, Canada) has an organ, Johannus Opus 1100 that was donated to the church by a member some years ago. Due to this sentimental value, a church committee approached me to see if I would repair the organ. It currently works to a degree but not all keys respond or play the proper pitch. Also, there is a low volume sound as if a key or two are stuck on and the pitch changes with the transposer switch.

    I was able to acquire a service manual from Johannus Orgelbouw and have been able to study the architecture to a large degree. I plan to basically clean the interior of cobwebs and dust and will remove each card and check/clean the contacts. It may all be just contact problems. But there may be surprises as well.

    The service manual has a few pages where the left side has been chopped - circuit wise, so that some circuity is hard to understand. The organ has an ALESIS board which I assume is for the "Catherdral" settings. This terminology is not on the schematic but appears to be associated with the schematic's "ECHO" features. There is a switch on the left side of the console above the "Cathedral" switch labelled "INT", blank, "EXT". I'm not sure where that connects to, but suspect to the "ECHO" section of the block diagram.

    I just wanted this group to know that I'm working on this organ as "hobby work" so it is not a paid position. :).
    I enjoy electronic tinkering and will use my electronic skills to restore this organ to the best of my ability. I have designed a microprocessor project for work back in the '80s but used the Motorola 6802. This organ uses a Motorola 68008 processor. So I have some familiarity with architecture of this organ.

    Last edited by jbird604; 06-16-2017, 01:12 AM.

  • #2
    Dear Peter,

    Where in Ontario are you located? We are a Johannus dealer and are willing to help. Message me privately if you wish.

    Best regards



    • #3
      Just south of the nation's capital - South Dundas. Peter.


      • #4
        Hi Peter,

        Sounds like you are nearly on the other side of the province from where I am.

        To start with, yes, a good cleaning of the key contacts with a solvent cleaner would be in order. De-oxiy is a good one. In a pinch I use an electronics solvent cleaner in an aerosol can in the auto parts section of the local Home Hardware. If there are a lot of dust bunnies floating around a can of compressed air first.

        The keyboards on the Opus 1100 are easy to get to if I recall correctly. There are two screws underneath plastic caps that hold the stop rail in place on the far ends. Remove the screws, then the stop rail, and set it on the music rack with the stop keys facing the music rack.

        The keyboards should hinge up now. If not, remove the screws holding the key cheeks in place.

        from here it should be easy to spot any key contacts touching the bus bars.

        You mentioned a steady soft tone that changes pitch when you rotate the transposer. Does this tone become louder if you add stops? Then it's likely a key contact.

        I don't have a schematic handy for the organ at the moment but hopefully this is of some help.



        • #5
          Yes, I'm not aware of any organ dealer near me except Fawcett Piano & Organ.

          I had emailed Johannus Orgelbouw and they kindly supplied two service manuals, OPUS 1100 and OPUS 1100N. From these I discovered that ours is an OPUS 1100N because it uses and ALESIS board.
          Some circuitry of a few pages in the 1100N manual were partially cut-off due to a bad scan. I sent another email explaining the missing schematic pieces and they sent me the OPUS 1200N manual which is scanned better and shows the complete missing circuitry. They assured me that the circuitry is identical for the section that the 1100N needs. So, manuals wise I seem to have all the needed schematics.

          I'm not a musician, and don't play a musical instrument, so I wasn't sure what these stops (white switches?) would do. But I will try your suggestion next time I visit the church and start some diagnostics. The console has a switch labelled "INT", blank, "EXT" and Johannus tech support indicated that it was a loudspeaker switch for internal, both and external. When I switched it to "EXT" the "always on tones" stopped. At the time I checked the organ I had no information at all and googling got me to this forum and finally to Johannus Orgelbouw. So, I'm making headway. I also have an oscilloscope if needed. - doesn't every electronic engineer? :)

          There is also a midi port. I have to check if our church office has a user manual to assist in how to use the various features of this organ. Finding a local organist is also a thought in case I need assistance to determine what it should sound like when playing normally.

          If any of you readers have circuitry modifications that enhance the usefulness of the organ I'd be happy to hear about it, but for now I'll focus getting it to run to factory specs.



          • #6
            Nico wanted some pictures of the Opus1100N organ. I'll try to see if I can get a photo of the key contacts.

            Click image for larger version

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            • #7
              Hi Peter. Thanks for the pictures. The organ is a lot newer that the old Opus 15N that I have but the way Jan has described for getting access to the key contacts is the same. Of course the 1100N may already be an old lady and organ arthritis and other ailments may have set in. The fact that the service manuals are still being provided by Johannus is a encouraging.

              I cannot quite see on the second picture just how the key contacts work but they look suspiciously similar to those of the 15N, namely thin springy wires making contact with the bus bars. The tab switches on the upper and side panels actually work in the same fashion as the key contacts. Those speakers are thunder houses and they produce very deep and pleasing sounds.

              In my humble opinion and based on my experience with the RiHa and the 15N I would venture a guess that your problem might well be with the key contacts and perhaps a good place to start. However, the construction of the electronics appear to be much more modern - for one the presence of ribbon cables confirms this impression. Be careful with those pesky little key contact springs, age might have caused it to weaken and they bend or break easily. It is easy to make them but Johannus will be able to provide replacements if necessary, I am sure. You have the advantage of a Johannus dealer in your country and willing to assist. That is always a plus point.

              Good luck and keep us posted
              "Don't make war, make music!" Hammonds, Lowreys, Yamaha's, Gulbransens, Baldwin, Technics, Johannus. Reed organs. Details on request... B-)


              • #8
                Next Thursday I'll try to get some close-up pictures of the contacts.
                I also dabble with Arduino microprocessor boards. Since each manual and other switch contacts go to a 16-pin ribbon connector, I plan to use my Arduino UNO to scan the ribbon connector, and along with some LEDs, as a custom-built tester for the keys and switches associated with their respective ribbon connector. This would allow me to view the LEDs from the console position while pressing keys and toggling switches.


                • #9

                  In those organs the data communications are done via MIDI. Why not put a MIDI Monitor on it and see what is happening. Also check the power connection from the power supply to to the processor board. That connecton is a source of problems in those organs.

                  PS. Roy Fawcett originally sold this organ. He re-labelled organs he sold as Principal. As far as I know, Fawcett is no longer in business. He was getting rid of his inventory about 6 months ago. He said then, that he was in poor health.
                  Last edited by arie v; 06-05-2017, 08:31 AM.


                  • #10
                    Yes, I talked to Roy about a week ago. His company sticker is on the organ. He said he has some parts for it. I did some work with him to repair some organs back in the '80s.
                    He even sent me on a Conn organ seminar for tech to repair the newer models coming up back then. I only helped repair a few. I believe one of his sons is still running the business and Roy assists when he can.

                    I don't have a MIDI monitor but will look into it. Is there a manual on how to use the midi features?

                    Back in the '80s I built a MIDI interface for my Radio Shack Color Computer but haven't done anything with it since then. I had bought a two manual reed organ from Fawcett but never learned to play an organ and our kids weren't interested so I got rid of it years ago. It used vacuum tubes, and even though I had vacuum tube electronic training and worked on vacuum tube airport surveillance radars, I was more interested in solid state electronics.

                    Thanks for the info regarding the card cage power as I haven't looked at cleaning the card cage unit and the boards. However, I still need to verify the manual contacts and will continue to build an Arduino keyboard tester.

                    If you have some familiarity with the Alesis echo board I wouldn't mind knowing where it connects to. The ribbon cable was removed and just dangles lose in the cabinet. There is an unused connector on the generator board and on the processor board marked "TEST". I don't have any info or pin signals for the Alesis board.


                    • #11
                      I got another chance to look at the organ today at the church. It turns out that it is an OPUS 1100, not an 1100N as I previously thought. The 1100 has a card cage with 10 slots. The 1100N has 12 card slots.

                      I removed the dual keyboard and took them home for testing. All keys and switches that the processor needs to know about are wired and grouped to 16-pin ribbon connectors. The switches are arranged in a 8 X 8 matrix thus allowing 64 possible switch contacts per 16-pin ribbon cable. So I built a key contact scanner using an Arduino board to emulate what the organ processor does. All manual keys work just fine. I also got to vacuum the interior and clean it from debris. I found ballpoint pens, music sheets, pencils, etc inside the unit. Don't understand how that got in there. I still need to check the switches mounted on the organ. That's for another church visit.

                      Organfella wanted a picture of the key contact mechanism, so here it is...
                      Click image for larger version

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                      • #12
                        Thanks and yes, quite different to my one - and a great improvement. Perhaps some stimulation to convert the ones giving trouble..... :P

                        "Don't make war, make music!" Hammonds, Lowreys, Yamaha's, Gulbransens, Baldwin, Technics, Johannus. Reed organs. Details on request... B-)


                        • #13
                          Had another visit to the church for more organ checks. My "Arduino cable/switches tester" (to simulate the processor scanner) worked and revealed that two rocker switches are intermittent. Will try to remove the switches for cleaning on my next visit.
                          Also, the upper 8 pedal keys (out of 32) don't work. Suspect they use reed switches. Will look at them at another time. The testing of the switches also revealed that the three toe switches are wired in parallel to the same functional console switches. Thus an organist can use either one. The toe switches have an LED above each switch for a visual confirmation as to the status of the toe switch.

                          I had removed, on a previous visit, the card cage which contains all the electronics for the organ so I could re-seat ICs and do basic board cleaning at home on the bench. The power supply card had an on-board bridge rectifier replaced with a non-pcb style of bridge rectifier mounted outside the card cage with their long wires and added heatsink. This simple fix works but I replaced it with a proper on-board bridge rectifier. It was for the 5V regulator circuit. I prefer to restore boards to their original state, where possible.

                          I didn't have a multi-voltage power transformer at home so I removed the power transformer from the organ and made the cables to properly drive the card cage power supplies. The power supply board creates the following voltages; +5V, +12V, -12V, +35V and -35V. These all checked out with the power supply card removed from the card cage and thus under no-load conditions.
                          I had also removed the two manual keyboards for checkup and cleaning as a number of keys were quite dirty (spilled coffee?). Both manuals worked in preliminary tests using my "scanner" tester.

                          I built a small bread board with 50 diodes to simulate any switch switch that the microprocessor needs to see (for stops and accessories). I need to get some ribbon connectors so that the swell and great manuals can be connected to the processor board (before I power the card cage), plus a few trim pots to simulate the swell and great pedals for volume control. I have some home-made dummy loads for the two amplifier outputs and can use some home speakers for testing the organ electronics. (With these parts one could now build a VPO :)) I'm enjoying this tinkering-repair project. Fortunately there is no rush to repair it as we currently have no organist.
                          Last edited by KOC62; 06-22-2017, 07:43 AM. Reason: added info.


                          • #14
                            Final Update:
                            After some "on and off" attempts to get this organ working I traced the main problem to the PPI chips on the processor board. Some of the pins were not producing output pulses for the switches/keys scanning function. Replaced the two 8255 chips and now we have a mostly working organ. There are a few keys and a few pedals that appear to have contact problems. This will be checked in the near future. However, the basic organ is now working.
                            I have to thank "Fawcett Piano and Organ" from Winchester, Ontario for lending me his box of spares as I didn't have these chips.



                            • #15
                              Great going there Peter!

                              Thanks for informing the Forum.

                              Happy organning!

                              "Don't make war, make music!" Hammonds, Lowreys, Yamaha's, Gulbransens, Baldwin, Technics, Johannus. Reed organs. Details on request... B-)