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Hammond BV - tone generator access/removal

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  • Hammond BV - tone generator access/removal

    Howdy folks!
    I'm new here at the organ forums. I've got a few project Hammonds that I've had for a year or two which haven't gone anywhere until just recently. One of my projects is a BV which will be getting a Trek II percussion kit, but first I have to fix a dead/missing tone (tone #50). I did the "jumper wire from #6 busbar to tone generator terminal strip" test and concluded that the problem is somewhere in the TG.

    I raised the manuals thinking beforehand that it would allow me enough space to access all the caps and inductors on top of the TG, but it realy only allowed me enough space to peer in. I could get my hand in there and lift up the green felt, but there's no way I'd be able to navigate a soldering iron around in there.

    So, it's clear that I've got some disassembly work ahead of me. My question is, what is the best way to get to the TG? Do I pull the manuals and work on the TG while it's in the organ, or do I pull the TG out and work on it on the bench? Or do I have to pull the manuals AND the TG?

    I know that either way, I have to unsolder about 100 connections, which I'm not thrilled about. Another nagging question is how do I test the thing after disassembly? If everything is disconnected, how can I probe the TG with no power to the motor? Is there a way to partially dissasemble the thing so I can get to all the goodies on top of the TG and still be able to run it too?

    Most of the capacitors I could see when I raised the manuals looked fine physically, but a few appeard to have "skin cancer". None of the bad-looking caps I could see pertained to tone #50, but I think some preventive maintenance might also be in order.

    Any guidance would be greatly appreciated. Thanks very much in advance!

  • #2
    welcome to the forum dillon,I to have a BV that I will be adding a trekII percussion,tho I have not yet had my hands inside the bv I understand your frustration,unlike all my other hammonds the bv is a "no easy access"it seems to me and it is only a guess but it looks like the twg would be easier to work on by removing the preamp and volume control box and few other obstacles at the back,once you have a better view of it I doubt you'll need to desolder the generator,the problem could be very simple but you just can't see it because of the limited view,good luck with your bv,I'll be watching out for your post's


    • #3
      I have a Hammond BC which is somewhat similar. During a move with the TG unlocked the organ acquired about 6 dead tones. My tech raised both manuals and blocked them up with chunks of 4x4 wood. Without removing the TG he was able to find the connections that had broken loose when the components on top of the TG had bounced up and struck the bottom of the lower manual. He soldered everything up and once again the organ worked just fine. He finished the whole repair without removing the TG.
      I know it's been a good practice session when I pause for a quick break, return and the room has a faint odor of Hammond oil in the air that only occurs when the console has been running for hours & hours.

      1940 Hammond model D organ with 1970 Leslie #122 speaker.
      1942 Hammond model BC organ with 1958 Leslie #45 speaker with 122 amplifier and two speed motors.
      1994 Allen MDS-3 theatre organ


      • #4
        Dunno if you want to get this involved, and dunno if it works on a B-V as it does with a B-3: make the cabinet top removable. If it's a living room grade unit I would not do this. If it's road grade, it might be worth it. It requires a hammer and a putty knife that's sharpened on one side and has a full length tang ('cause you're gonna be banging on it - a lot). (Of course the proper way is to steam the joints apart, but that didn't work.) With the top off and some carefull fiddling, the manuals can be stood on their backs, giving full access to the TWG.


        • #5
          Thanks for the inpus so far guys.

          Charlie - Does your BC have the preamp and volume box mounted to a big aluminum crossmember that spans the width of the organ, or is it mounted to the wood at the bottom of the cabinet?

          The organ is pretty clean. It's not perfect now, but it will polish up real nice when I get to that point, so I don't plan on modifying the woodwork. Hammond could've helped us out here with a removable top or knee board.

          What is it that makes the tone generator so accessible on a B3/C3 but not on the older models? Is it the location of the preamp and volume box? Did the B3/C3s have more generous wiring length?


          • #6
            I changed the entire generator tray on my C3 using the access Charlie described and my job involved a lot of soldering!


            • #7
              Ahh...pull the whole generator out and use your kitchen table and while watching baseball recap the whole thing....its a once in a life time experience! In the end you'll wish you had!
              Allen 5300-DK, Hammond A-105, Conn Custom 905-DK


              • #8
                I'm tipping the manuals upward like the hood (or bonnet, for those of you on the other side of the pond) of a car. Should I also be lifting the back of the manuals up as well? Do I need to slide them forward or backward as well?

                I have it blocked up right now about as far as it seems reasonable to push it. The drawbar unit is less than a centimeter from the delay line. I could raise the front a little higher, but not much. I also had to unbolt the frame that the amp and volume box are mounted to and slide it backward to allow the manuals to tip this far. I'd say they're tipped about 30 degrees.

                Am I doing something wrong? Should I be able to tip them more than this?


                • #9
                  Originally posted by Hamman View Post
                  Ahh...pull the whole generator out and use your kitchen table and while watching baseball recap the whole thing....its a once in a life time experience! In the end you'll wish you had!
                  I almost certainly will re-cap the whole thing as the volume is quite "wavy" from note to note, and I understand this is a sign of badly-aged caps. However, I really want to track down the missing note problem first. If the problem is a capacitor, than a complete re-cap will certainly fix it, but then I will not have learned much about troubleshooting these things. I think pinpointing the problem will be good experience gained. And it may not even be a capacitor, in which case I still have a problem on my hands.

                  Anyway, I just went downstairs and took a second crack at these manuals. I tried pulling the manuals forward (toward the front) a few inches and that was all it took to tip the thing up further. Now it's closer to a 45 degree angle. Still a little tight for soldering IMO, but doable. Guess I was just being a wimp. I was afraid I'd break wires or bash the back of the manuals into the preamp tubes if I tried to tip it any further.

                  So now the question is: How do I get the green felt off? Do I just "un-button" it from the oil cups, or do the oil cups unscrew or come out in some way? Not sure which way I'm supposed to go, and I don't want to get rough with it and tear the felt when I should be removing the oil cups or snap of an oil cup that isn't supposed to be removed.

                  Thanks again everybody!


                  • #10
                    There should be incisions in the felt at the funnels allowing removal.Have a closer look.