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Conn 653 Pedal Tuning

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  • Conn 653 Pedal Tuning

    Anyone here familiar with the procedure for tuning the pedals on a Conn 653 Type 1 theater organ? In particular, there are three pots on the on the Biphonic Generator (125-5017-01) board that affect pedal tuning. The one I'm interested in is the High Note Adjustment pot. It's been a lifetime since I've had to tune the pedals and for the life of me I can't find anything, including the alternate 5th, that is affected by this pot. My Conn literature for the organ doesn't include a pedal tuning procedure. Any ideas? -Stephen

  • #2
    The 652 used the same circuit but the low and high pots had factory selected resistors. The 652 schematic shows 10 k for the high and 39k for the low. Perhaps setting the pots to those values would be a good starting place.
    Also the 652 pedal tuning procedure tunes the low C pedal using the 16' diapason voice.

    Have you tried holding down two pedals of the same note to see if the High pot has any effect?



    • spcline69
      spcline69 commented
      Editing a comment
      Hmmm.... no I haven't tried that but have verified that I can play two or more pedal notes at the same time. Will give that a try. I have been using the 16' for tuning and checking the other's. Thus far, I tune C1 first with the multiturn master tuning pot. Then step up to C2 or C3 and tune with the low note pot. I'll give your suggestion a try and and get back to you here. I wasn't aware that the 652 had the same tuning system with the exception of the two fixed resistors that you mentioned. It's been years since I have tuned a pedal board. The 653 was came out just after I left the business. I do have most all of the service manuals (and excerpts), schematics etc. Living in Alaska those are good things to have!