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Conn Serenade 634 Type 3 Repairs

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  • Conn Serenade 634 Type 3 Repairs

    I'm looking for some advice on repairing my Conn Serenade 634 Type 3 organ, which I just acquired from its original owner. There are two problems that I would like to fix.

    I am a harpsichord technician, so tuning was no issue, but I know nothing of 70s circuitry. All of the Tibia stops in the manuals are working fine, but none of the diapason, reed, or string stops sound. However, the reed and diapson in the pedal are working fine. I realize that there could be a variety of issues here, but how might a layman go about isolating the problem?

    The only other pressing issue is with the low B in the pedal. When played, the low B repeats the tone of any lower note played previously. e.g. after playing the lowest D in the pedal, depressing the low B will sound at D pitch. However, playing the D above low B in the pedal has no effect on the B pedal's pitch.

    I will probably end up getting a pro in here to look at the thing either way, but I'd love to do some work on it myself if possible. Thoughts?


  • #2
    If the Reeds are dead on both manuals, open the lid of the organ and look for a board labeled "Post Amps." It will have two volume controls, one for flutes and one for complex. The complex channel is for all the reeds, strings, etc on the keyboards. Try moving that control to see if it has a dead spot. You will need a small screwdriver to do this. If that doesn't help we can troubleshoot it further if you wish.

    The bass has two separate generators, one for the first octave and one for the second. If all the notes are in tune then I suspect the contact that tunes the B pedal is not making but the keying contact is. Look at pedal contacts on the B pedal.
    They're accessible from the back of the organ behind a masonite panel usually.

    Servicing electronic organs since 1969.


    • #3
      Thanks, tuscondave. The pedal issue was easily resolved; one of the two spring contacts had disconnected.

      I was able to locate the complex post amp control, which was still at the factory setting. While turning it, the speaker crackled, and when turned almost all the way up, I could get something out of those stops. The upper manual was louder than the lower, but both are still too quiet when cranked up. Also, the volume of individual notes was inconsistent, and the speaker hummed audibly at this level. If you don't mind, I would appreciate any further tips!

      Thank you.


      • #4
        Sounds as if you still have the original vinyl bussbars. That will have to be addressed first. The normal fix is to replace them with gold plated rods. I don't know if Organ Service Corp ( still has them. There are 5 total of them for the keyboards.
        (see the thread on Conn 650 contact cleaning in the Theater Organ forum)

        Work the post amp volume controls or spray them with some deoxit until there is no more static when you move them.
        You can then do a quick check on the post amps. Touch the points marked 3 and 18 one at a time with a finger. You will get hum from the speakers. 3 is the tibia, 18 is the complex channel. If the hum volume is close to the same then the problem is before this point.

        The inputs to the post amp are 9 tibia and 15 complex. Touch these with a finger and see what you get.
        After the post amp there is the "fast Express" switch. Try rocking that also.

        Last edited by tucsondave; 06-29-2014, 03:42 PM.
        Servicing electronic organs since 1969.


        • #5
          Sorry, the gold bars are LONG gone. Do some research on this forum on that subject and you will find the current solution.

          . . . Jan


          • #6
            Thanks. I'll look into it.