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Hammond Manuals |
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We provide standard maintenance procedures for the manuals, including critical bussbar repair, cleaning, and lubrication. Bussbar service may be the single most important maintenance to any Hammond organ, and will dramatically improve the sound and response of most organs. Much like the generator, the manuals are the "second heart" of Hammond organs. Missing frequencies are often the result of broken switch stack resistance wiring, which we can trace and repair in many circumstances. We also provide ProKeys key "glassing", a special polishing process which renders the playing keys as smooth as glass. For this process, we specifically do not use a bench grinder, which produces inferior results. The MANUAL FOAM Problem Sometime in the mid to late 1960s, the exact date unknown at this point, Hammond started using FOAM to seal certain areas of the manuals against outside dust and dirt. Riveted felt was used previously. From a production standpoint, the foam, with its adhesive backing, required less labor, and virtually no machinery to install, was far less expensive, and probably seemed - at that time - to be a viable alternative to the felt which the foam replaced. Unfortunately, Hammond was wrong. The foam used by Hammond was an early composition which may have accomplished some degree of dust sealing, but is now known to be EXTREMELY detrimental to the manual resistance wiring which it comes in contact with. The foam and its adhesive backing definitely will deteriorate over time, and turn into a sticky substance, resembling tar. Typically, the decomposition would not be a problem, except for the fact that a chemical process occurs as the foam disintegrates. The foam in each manual is actually 2 separate strips mounted on the back manual cover. One runs the entire length of the manual and the other is a shorter piece, sealing the area where the preset wires exit the manual. As the foam disintegrates, it expands, actually doubling or tripling in physical size, and embeds itself in the resistance wiring loom, which is plastic in the later models. This can chemically cause the plastic to deform and melt. Of course, it also embeds into the resistance wiring. The wiring inside the later Hammond manuals is a very light gauge non insulated wire - by this I mean there is no cloth covering as in the earlier manuals. It is very similar to the wire used to wind coils. Its only insulation is a lacquer finish directly on the wire. The chemical decomposition of the foam eats through not only the lacquer finish, but also eats right through these ultra fine wires. I've noticed that this process seems far worse on Hammonds that are moved a lot. Possibly the shock and vibration of travel accelerates the foam's action on the wiring. You can believe it is a major problem to attempt to trace and repair these light wires when they break. And in some cases, repair is virtually impossible. Removing the foam residue from the manual back covers is a filthy, sloppy job. I haven't found any chemical that completely loosens it. Wire wheels just clog up, sandblasting does nothing to it at all. Scraping out as much as possible with gasoline and a razor knife is as close as I've come to complete removal. While not every Hammond with foam insulation has shown evidence of this problem, it's clear that time is a factor in the deterioration process. It will happen, sooner or later. ADDENDUM: When I first wrote about this problem publicly, about 1996, I was laughed at and ridiculed by most of the internet Hammond experts. Since then, I've received "HELP!" calls from at least 20 different Hammond owners who have discovered the same problem in their own Hammonds. Most have been 100% successful in restoring missing frequencies, but some have not. Is seems some world class Hammond experts aren't really experts after all. Three Hammonds which I rebuilt with this manual foam problem were, unfortunately, total disasters. It was necessary in all three cases to replace both upper and lower manuals with older manuals which had felt insulation. All three organs had at least 30 broken resistance wires in each manual, and tracing both ends would have taken weeks of intense labor, which the owners were unwilling to pay for. Understandably, it's very difficult to find a pair of manuals when you really need them, so the cost factor in all three of these Hammonds was outrageous. The other Hammond which suffered from this problem was very easy to fix. Only four wires were actually broken, so locating and resoldering was quite easy. click picture for fullsize view
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