Hammond BV Smooth Drawbars Conversion Continued

22. With the original drawbar slide fitted back into place, put the bent contact/wiper into the top of the slot

23. Then re-fit the screw and tighten it. You can clearly see that the contact is now bent

24. Here's what you want each of the new contacts to look like. Just bent enough so that it makes a good contact when the drawbar is pulled out, but not bent too far, or the contact won't work when the drawbar is pushed all the way in.

25. Notice how the contact retains enough spring to keep the wiper point in contact with the PCB traces over full travel of the drawbar

26. Here's the old contact and a new one side by side. There are some differences, and I'm not sure if they are deliberate or not - either way, they work well.

27. Here's what you should have when all the drawbars and new contacts have been reassembled into the drawbar unit. Fit it back onto the organ.

28. Solder a terminal ring onto the end of each of the wires on the new drawbar connection wiring harness

29. Screw the new harness contacts onto the end of the busbars in the back of the organ. Make sure to get the colors right.

30. Feed the new drawbar PCB connector end of the harness through to the drawbar unit

31. Solder the labeled wires to the correct drawbar contact. Make sure to bend the wire through the hole before soldering it in place

32. Continue on up the drawbar unit being careful to get the wires in the right order - the colors of the old wires will be very faded and difficult to identify without the number labels you added earlier. Also, be very careful not to drop hot solder on any of the plastic keys - it will ruin them instantly!

33. Screw the drawbar unit down firmly and then arrange the wires so that each drawbar can travel in/out freely. You will then have to make minor adjustments to the new drawbar contacts with the organ turned on. This is a fairly tedious process but one that's worth paying careful attention to. The playability of the organ depends directly on how much care and attention you pay to this final trimming stage. You may have to unscrew and completely remove some contacts to re-bend them as required.

Once you have all the drawbars trimmed out and the wires running clear and free, reassemble the music stand/top of the organ and you're all done. I hope this description proves to be of some use to someone. By all means, write me and ask questions etc. (email ID is in the picture below).

Regards,

Dave Fifield

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