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Conn 652 repair?

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  • Conn 652 repair?

    Hello all,
    I'm rarely on this site but I figured I'd give a try to see if someone might be able to help me.
    I have a Conn 652 in (visually) pristine condition but it has some issues. When I turn on some stops, I have a couple notes that play (like a cipher) without touching the keyboard, a couple others that don't work at all or just produce noise.

    After reading threads in the forum, I'm surmising that it's not possible to fix or if it is, it might be a labor intensive effort. I would at least like to have a technician take a look at it to see if if it is repairable but I'm not sure if I can find a tech to do that. Actually have no idea where to even begin looking for a tech.

    Regardless, I do need to get rid of it. I'm downsizing and will no longer have room for it.
    I'm in S.Florida (east coast). Can anyone point me in the right direction?

    Thanks! Ed

  • #2
    Visit www.mitatechs.org and look in their listings of organ technicians. Florida is (or was) an organ hot spot but alas technicians able and willing to work on oldies like the 652 are quite literally a dying breed. Fletchers Music have branches in Florida and they may know of someone near you so perhaps worth giving them a call too.
    It's not what you play. It's not how you play. It's the fact that you're playing that counts.

    New website now live - www.andrew-gilbert.com

    Current instruments: Roland Atelier AT900 Platinum Edition, Yamaha PSR-S970, Kawai K1m
    Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
    Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.
    Retired synths: Korg 700, Roland SH1000, Jen Superstringer, Kawai S100F, Kawai S100P, Kawai K1


    • #3
      Being realistic, if you need to get rid of the organ, just give it away for free. It will go to a hobbyist who will either fix it, or will gut it and use the console for a VPO. The cost for a professional repair will probably be higher than the retail value of the organ.
      Ed Kennedy
      Current Organ - Conn 645 Theater


      • andyg
        andyg commented
        Editing a comment
        A 3 manual AGO console should never be given away free. There are indeed plenty of people who would want it for a 'driver' console for a virtual organ. And the dog-leg theatre style bench would have a good value on its own. Potential buyers will be looking for a bargain, for sure, but most are well aware of the values of larger consoles.

    • #4
      I have a Conn 652 where the pedals don't play at all. I have re-soldered all the connections, checked voltages and replaced LSI's and still nothing. If you are thinking of discarding your 652, I would like to get the pedal circuit boards from you. I'm on the West Coast of FL in the Ft. Myers area.

      My 652 plays OK except the pedals began to just rumble and then only occasionally produced the correct tone. After researching the problem, the common fix seemed to be to re-solder the pin connections on each circuit board for the pedals. After that no pedals sound. All three upper manuals play OK, with no apparent issues. I double checked all the pin connections and these appear to be OK. I've checked the voltages and they appear to be OK. Possibly I have made an error putting the various connectors back on the boards but I can't tell. All the connectors lined up OK. Only one board was worked on at a time but I did not check the organ after each one was worked on. This was a bad move on my part as now I can't narrow down where the real problem might be. I'm looking for some guidance beyond the obvious. Yes, I have a copy of the service manual and the schematics but these are difficult at times to follow. Any advice will be greatly appreciated.
      Last edited by myorgan; 04-17-2021, 05:41 PM. Reason: Merge combined thread posts.


      • jbird604
        jbird604 commented
        Editing a comment
        Captain, you should get with the OP and perhaps take in his old 652 as an ongoing parts source. It would be worth the trouble of going after it, IMHO.

    • #5
      Why don’t you post the relevant part of the schematics, and we can help you figure it out? Also, don’t forget the first step in troubleshooting an old organ is making sure the power supply is ok.


      • #6
        Would this thread get a better response in the "Electronics Repair...." section?


        • myorgan
          myorgan commented
          Editing a comment
          I merged the posts so Capt. Ernie's responses will be in one thread. Be patient Regeron, someone will usually catch multiple posts and correct any possible issues within 12-24 hours.


      • #7
        Capt. Ernie,

        Do the pedals trigger the keyed drums? Bass, conga, & snare.

        Also the pedals are connected to the rhythm and alternating bass circuits including switches. There's much more to pedal function than the generator boards.



        • #8
          To all that have responded - Thank you! To answer the questions:

          The pedals do not trigger anything from the rhythm section. I can get a very soft scratchy sound from the top 7 pedals if I have the Accomp to Pedal 8 on and the Accomp Tibia stop(s) on.

          The +/- 5VDC and 14VDC is OK. In the Service Manual, page 111B, upper right corner the Pedal Keyer Pin Connection Chart shows that Plug A2 (White/Yellow) should have 32 VDC on it. It doesn't and I can't find how the 32VDC gets there to trace it. I've had the power supply out and checked the fuses and they are OK. Of course it's not easy to get into Plug #3 to see if the 32VDC is actually there so I'm trying to find another place to check it. I can't find it, yet.

          I've sent a message to the OP above about parting out what he has but haven't heard back yet.


          • #9
            First thing if not already done is to reflow the solder on the plug pins on the regulator board.
            While the board is out check for C940 in the 32 v regulator being shorted.


            • #10
              I checked the voltage between pins 1 & 7 and found 33.0VDC. Correct me if I'm wrong but I'll presume that the C940 is OK at this point. The solder on the pins looks fresh and I checked for continuity on all of them and found everything good and solid. I will have to try and see if I can trace this voltage back to the boards.


              • #11
                I found two connections, plugs C-1 and C-5 reversed on both Pedal Keyer Boards. Reconnected these and the top 7 pedals play but only single pedals, not two at a time. I traced all the other connections and they look OK. Making headway but not there yet.


                • #12
                  Maybe drive line signals D, E, and F, are missing. You could try swapping IC's 701 and 702 on the pedal generator board to see if there is any difference.
                  Did you track down the missing 32 volts?