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The Tone Generator Is The Heart Of A Hammond |
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Mechanically, Hammonds operate on a very simple principle, much like a motorized electric guitar. Tonewheels turn at extremely precise speeds in close proximity to magnetic coil pickups. This is exactly the same idea as an electric guitar, except the Hammond is "playing" all of its notes constantly, whenever the generator is spinning. These tones are "let out" of the Hammond by pressing keys, which completes a circuit, sort of like turning on a light. If no keys are pressed, the generator is still producing the sounds, they're just not being allowed out into the preamplifier circuit to be heard. The more serious models of Hammonds (B3, C3, A100, etc.) require a start motor as well as a run motor. The start motor has the power (torque) necessary to overcome the inertia of the wheels and shafts, but the run motor doesn't. The run motor, although much less powerful, is designed to synchronize with the 60Hz power line, and supply a very accurate rotation speed to the generator. Line frequencies above or below 60Hz will cause the Hammond to change pitch, but typically, voltage fluctuations won't. See the Power page for more details about a stable power supply for Hammonds. Console generators consists of 91 tonewheels, having several different outer shapes, or "teeth", which rotate at different speeds, creating various frequencies. In the center of the generator is the main driveshaft which is spring coupled to the run motor. This shaft causes the drive gears to rotate, which in turn, drives the tonewheels. Each tonewheel has a spring clutch. Two tonewheels, two clutches, a shaft, plus one driving gear make up one complete tonewheel assembly. Each side of the generator is divided into sections, or bins, and one tonewheel assembly rotates in each bin, in close proximity to the magnetic pickups. If you're looking carefully at the pictures, you'll see that's a LOT of gears and shafts and bearings for all this rotation stuff! And you're right - there are 110 bronze bearings in a 91 wheel generator, each with its own oil wick. Every one of those points needs oil. When the generator was first manufactured, it was clean. The entire lubrication path was fresh and clean. The bearings didn't have 25-45 years (or more) of accumulated dust, oil residue, gunk, and grime buildup - they were brand new. Now hold on just a minute .... Before you say "this guy's crazy!" - wait - make a test for yourself. Put a few drops of generator oil on some aluminum foil, and place it in the top of a closet, out of the way. Go back and take a look at the oil after about 4 weeks. Or after 4 months. You won't even want to look after 4 years! It's not clean anymore, is it? Airborne dirt and dust are attracted to oil like magnets, and the Hammond generator is no exception. In the closed back organs (B3/C3/RT3, etc.) there may be less dirt, but there sure is dirt. And there's a WHOLE LOT MORE dirt than there was 10 years ago. The open back Hammonds (A100, etc.) accumulate a lot more dirt and dust than the closed back models. None are exempt - unless they live in a huge plastic bag! If you look carefully, you'll see the generator oil funnels inside the Hammond. Examine the felt over the generator. If it's at all dusty and dirty, isn't it logical that dust and dirt are also in those funnels? So where does the dust go when we pour oil in the funnels? I believe the oil carries the dirt particles right along the oil wicks, and deposits it on each bearing. After 30 or more years of this, it seems sensible that those bearings need a deep cleaning. Is this an article about dusty houses and insufficient cleaning? Am I trying to sell vacuum cleaners? Emphatically NO. It's about FACTS - 25-55 years of airborne dust particles, oil residue, and gunk are in virtually every Hammond generator and vibrato scanner on this planet. At some point or another, the dust, grime, and dirt will have an effect on the rotational ability of the shafts and bearings. Many organs have already shown these effects, many others haven't. It's just a matter of time and dirt. The use of questionable oil just adds to the problem. Some oils will gum up a lot sooner than others. Old oil is already beginning to oxidize and gum up, and should never be used. This especially includes that ancient tube of official Hammond oil that's still inside the organ from 1962. Electro-mechanical devices cannot last indefinitely without considerable, detailed, in-depth work, cleaning, and restoration. Hammond's production line closed down in 1974 - meaning that the most recent tonewheel Hammond is about 30 years old. Maybe this gives you something to think about. ProKeys has developed a way to remove the majority of the accumulated dirt and residue. It's been really effective in resolving several "dead" generator problems. We have a special "generator bench" for this specific purpose, the generator remains upside down, blocked up level, and running continuously for 3 to 4 days - and occasionally longer - while we deep chemical clean all bearings, drive and tonewheel shafts, and oil wicks, then blast them dry with compressed air. 125 lbs. of compressed air moves a lot of dirt around, you'd be amazed at the mess this creates. We use a long hypodermic needle to get fresh oil directly where it's needed. Then we repeat this process several more times, drying and wetting the bearings until we're satisfied. Believe it or not, we actually use a medical stethoscope during this process to pinpoint specific bearings! We're able to chase down almost any noise, anywhere in the generator. While we're in there, we clean and demagnetize all the tonewheels. During this process, old oil is chemically reduced, removed, and fresh oiling takes place constantly. We ONLY use a crystal clear oil which we've believe is far superior to any other type, including official Hammond oil, which we will no longer touch. When we're finished, the generator will come up to running speed within approximately 2 seconds. It's nearly inaudible from about 1' away. The old fashioned "hold both switches on" way of starting the generator is totally unnecessary after this service. In fact, in recent months, we've implemented an unusual test .... we engage the start switch for about 2 seconds, then release it. We then wait for 2 seconds as the generator "spins down", and then activate the run switch. The run motor synchronizes immediately. This test illustrates conclusively that the entire generator and scanner assemblies are nearly friction free. Here's a message from one of our
Hammond friends who is also one of our "generator clients":
And a message from another
Hammond friend who did the generator process himself:
Will your generator do this? The ProKeys process restores correct generator performance, and removes 25+ years of accumulated oil residue and dirt. Our Hammonds have occasionally come out of freezing cold trailers and started immediately - no hesitation, no grinding. We're convinced that this generator service is very important for any tonewheel Hammond. And ...... since we've publicly explained this (for approximately seven years) - hundreds of other Hammond fanatics have tried it. To our amusement, some of them even think it was their idea! I'm extremely happy to report that since I wrote this page, several Hammond players have shipped their generators to me for work. To date, every generator has arrived in fine condition, thanks to extra careful packaging. Thanks a million, guys! It's a pleasure to work on these generators and scanners! click picture for fullsize view
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