John, one of the Hamtech list folks, posted a message saying that he was looking for an A100 cabinet to trade for an A102 cabinet that he had. His goal: the use it as the basis for a chopped Hammond--and he did not want to destroy a really nice A102 cabinet in the process. I volunteered, and so began the project documented on this page. We began by systematically unbolting the Model A guts from the A100 cabinet to get ready to pull the works out--the idea being to get the whole thing out more or less as a unit, hopefully avoiding disconnecting the manuals from the Tonewheel generator. The next morning I started by building some brackets to be mounted on the top of a folding table so that the entire Model A guts could be slid out of the A100 cabinet onto the table, then into the A102 cabinet, after preparing the A102 cabinet by drilling the appropriate holes and making the appropriate adapter blocks. Here's what the guts looked like on the table: During the removal of this assembly from the A100 cabinet, it occurred to me that this was a golden opportunity to swap the keys in this organ for the M2/M3 keys I had acquired for this purpose last year. So I started by blocking the drawbar assembly up out of the way (as shown in the picture above) so I could get at the keys and channels of the upper manual. I started by removing the high C key and channel. The first thing I noticed was that the key is mounted differently from what I had seen before. Instead of the little leaf spring at the rear of the key channel, each key is mounted on a threaded post, with a spring and nut to hold the key and provide adjustable tension for each key. In addition, the key channels are extruded aluminum instead of the stamped sheet metal I had seen in the other Hammonds organs (The B2 MIDI Controller and the M2) I had worked on. Here's a closeup of the key-tensioning mechanism: There was no need to replace the black keys--they don't have the sharp side edges that the white ones have. So I began the process of removing the white keys from their channels and discovered another little difference: the screws that hold the Model A's keys on the channels are a lot smaller diameter. The newer M3 keys I had fit the channels just fine, but the screw holes in the channels were too small, so two holes on each channel had to be drilled out to the larger size. In the picture above, the Model A key, channel, key mounting screws, and tensioning spring and nut are on the left, while the M3 key, channel, and key mounting screws are shown on the right. The picture above shows one of the aluminum key channels on the drill press table immediately after it's holes have been enlarged. Once the key channels had been modified, I mounted the M3 keys in the upper manual. Another HamTech member had provided a suggestion for adjusting the key tension to get it uniform across the keyboard: Place a weight on each key, then adjust the tension nut so that the key just barely comes up to its resting position. I used a 9/16 socket from my 1/2-inch drive socket set. Worked just fine. The other thing worthy of note is that the method used to keep the keys aligned and moving up & down smoothly is different in the Model A. Instead of a small felt pad riveted to the underside of each keycomb tooth, the tooth is wrapped with cotton cloth tape, which is held in place by a small brass clip. Like this: These keycombs are 67 years old, yet they still perform well, with only a slight amount of clacking during a gliss. The keycombs in the B2 manuals I used for the B2 MIDI Controller project were in much worse shape than these! The next picture is of the A102 cabinet's main shelf, after I prepared it for the Model A's tonewheel generator by drilling holes for the spring suspension and lockdown bolts: In the process of moving all of this into the A102 cabinet, I noticed that one of the signal wires had come loose from its connection on the back edge of the tonewheel generator--this was the only such problem I encountered. After the swap was completed, I tested the organ through my little Marshall guitar amp to make sure everything was working right. Here's a shot of the organ after I moved it into the living room: And another one from the front: Next, a shot of the keyboards from the front. If you look closely maybe you can see that the upper manual's white keys look a little different, having been transplanted from an M3: In this picture you can see the fact that the side blocks the manuals are mounted to are actually slightly taller than the side walls of the cabinet. This is because the Model A manuals are mounted an inch higher than the original A100/B3 style manuals because more clearance was needed between the tonewheel generator & the manuals than the cabinet design allows--so a 1" high spacer block has been added on each side to raise the manuals up an inch. These blocks were made by the guy that installed this Model A in the A100 cabinet, so I just moved the spacer blocks to the A102 cabinet. You can see the back end of the spacer block in the picture below The result? The tops of the manual side blocks come up about 1/16" higher than the sides of the cabinet!        <----Spacer Block Right here! This means I can't put the top on the organ until I work out a way to mount it so that it looks good up there! One more picture, in which you can see the near-side manual side block peaking up over the side wall of the cabinet: A couple of things worthy of note: The lockdown bolts were in place when I started this project--but I haven't put them back in yet, and the TWG runs quieter this way! The fellow who installed this Model A in the A100 cabinet had bypassed the preamp entirely, which is why this organ does not need an external B+ supply to work. There's a 1/4-inch phone jack box installed under the TWG shelf that gets its signal from the box that has the interconnections for the mixing transformer output and the inputs to the tremolo generator and the preamp.

All Pictures and Text (c) Copyright 2003 by Stephen Cyr Last updated December 23, 2003

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