Hammond Chord Organ Mini FAQ

Hidden dangers of old Hammonds

I'm not sure if Hammonds in general were ever UL-approved, but clearly they wouldn't make the grade today. In the Chord Organs and many other models, the back was open with the tubes and kinds of other dangerous stuff exposed to whatever happened to be passing by. Not like the "no user servicable parts inside" philosophy of the modern world.

While the Hammonds started out with a carefree attitude toward electrical safety, the passage of time has done nothing to improve things. When old components fail, they may create a shock of fire hazard.

The best approach is to have your "new old" instrument checked out by qualified technician before you even plug it in. The cost of such a checkup might exceed the value of the instrument, but it won't exceed the value of your life. Take a look at the Musical Instruments Technicians Association website to find a tech in your area.

If you're a brave soul with a DIY bent, the next best approach is to have the fire department standing by (fire and paramedics, that is), keep your left hand in your pocket, and do some reading up beforehand. As a first step, be sure to take a look at the safety tips section of the excellent sci.electronics.repair FAQ for suggestions on how to avoid injury when servicing electrical equipment.

Here are some potential Hammond-specific perils for you to fret about. Consult the resources on my Hammond Links for more information. In any event, please don't sue me.

Power cords. They tend to be rather crumbly, even in a 60s-vintage instrument. The power plugs are made of "molded mud" and tend to want to return to being just plain mud after 40 or 50 years dutiful service.
Fortunately, the power cord in a Chord Organ is easily replaced by anyone capable of a little soldering. (Again, the sci.electronics.repair FAQ can help with some soldering tips.) You can probably find a suitable replacement cord at the hardware store.
Of course, replacing the power cord does mean removing the "power pack", which exposes even more dangerous stuff. Watch out for those nasty capacitors, which can zap you even after the organ's been unplugged a while.
You should probably replace the grommet which holds the power cord in place at the same time. The grommet may require a trip to the electronics store. Replacing the grommet is actually the dangerous part -- I always a manage to pinch myself, causing a nasty blood blister. (I suppose there are special grommet-inserting pliers to be had for a small fortune.)
At least one correspondent reported that the solder connections had simply dried out, and that resoldering them restored the instrument to service. (Hope he replaced the whole cord, actually....)
Crumbly power cords hit the tonewheel Hammonds, too. And many or most tonewheels have ordinary lamp chord (zip cord) running to the Start/Run switch. The insulation on that lamp chord gets pretty crumbly after a few decades.
Fuses/Circuit Breakers. Hammond had a simple philosophy: we don't need no stinkin' fuses! Unfortunately, failure of a component such as a tube may result in the famous "short circuit", which may mean lots and lots of electrons showing up where they aren't expected, which in turn leads to heat, and thence to "organ failure".
The author's Hammond A-100 suffered just such a fate, which resulted in the transformer in the preamp overheating and emitting a fair amount of unpleasant smoke, despite the instrument being shut down within seconds. And guess what, they don't make those transformers any more, although Trek II sells an expensive replacement (a little under $200, but includes a fuse) or a complete solid-state pre-amp costing a lot more (h'mmm...an upgrade).
There's no really easy solution to this problem. Keeping the organ plugged into a power strip with its own circuit breaker may help, especially if you can find one with a rating lower than 15 amps. Even so, there may be serious damage long before the breaker trips. Using an outlet protected by a ground fault circuit interrupter (GFI or GFCI) may also help. A professional technician can install the fuses or circuit breakers missing in the original design.
Grounding. Once again, Hammond philosophy is "Keep It Simple, Stupid". Translated, this means: we don't need no stinkin' grounding! This is kind short-sighted simplicity, especially when your design involves wires with crumbly insulation connecting to metal pieces the user may touch.
Again, plugging the instrument into an outlet protected by a ground fault circuit interupter can't hurt, nor can an using an outlet with its own ciruit breaker. But the real solution is to have a professional technician install proper grounding.
High voltages. Those tube amps put out some third-rail voltages. The famed "B+" voltage is something around 450 volts. AC, DC, don't matter could spoil your day. Back in the days of minicomputers, I heard stories of a couple of technicians being fried due to a carelessly placed 5 VDC trace on the backplane of a particular system....
Hot tubes. OK, those tubes get pretty hot. And they are made of glass, pretty sturdy glass, but they still may break if you drop them. Gloves are a good idea, as is eye protection.

How much is it worth?

OK, I wanted to get those safety concerns out of the way first. "How much?" is the most frequently asked question by far. Unfortunately, the answer is...not a whole lot.

I heard stories of Chord Organs being given away or thrown in the dumpster. One upstanding member of the Hammond community confessed that he couldn't see keeping seven chord organs, so he (gasp) cannibalized them for parts (the horror).

Some folks have picked up a chord organ for a few bucks at a house sale or a thrift shop.

Before the Hammond Organ Company, Hammond made clocks. There is a lot of collector interest in these clocks.

Hammond made a few organ models which are pretty scarce, like the Novachord. (As you may have heard, "no va"" means "doesn't work" in Spanish....) There seems to be some level of interest in these. But most of the interest in Hammond organs is centered around the B-3 because of its cool factor, with even the electrically and sonically very similar A-100 series lagging behind, followed by the later-model C's and D's.

Older model tonewheels and tonewheel spinets such as the M-series seem to be much less valuable, with Chord Organs almost at the bottom. Solid-state Hammonds from the 70's such as the H-series are probably the absolute bottom (you may wind up paying someone to take them).

So if you love your Chord Organ, keep it, but don't haul it down to the Antiques Road Show. If you don't love it, try to find it a good home, or at least a friendly Hammond technician named "Hannibal". (Better for it to be an "organ donor" than "dumpster fodder".)

My online buying/selling suggestions are eBay (search eBay for "chord organ"), where I recently bought a chord organ, or the free organ classifieds at theatreorgans.com, where the ads are free, and in some cases, so are the organs.

How do I turn it on?

The S-100 has a on/off switch, so that one's easy. Older Chord Organs have an "expression lever". that's both the on/off switch and the volume control, much like an old radio or TV.

The expression lever is located under the keyboard. It's usually held in place by a metal clip. Slide the lever out from under the clip, then turn the end downward and to the right (counter-clockwise) to turn on the organ. When playing you hold the lever on your right knee, and move it to the right to increase the volume.

Be gentle...force is not required.

Starting tonewheels can also be a challenge to the novice. Much like a classic Harley, Hammonds burn oil and are hard to start. And both are popular with Steppenwolf fans. (OK, they only use a little very fine oil, and starting them is not that hard. And most Steppenwolf fans are probably in nursing homes by now.)

Starting a tonewheel Hammond is just like starting a car, except the switch is different. With a car, there is one switch, which you turn to start for a few seconds, then release. A spring pushes the switch back to the "on" position. If you hold the switch on "start" for too long, or move it to "start" when the engine is already running, a horrible grinding noise will inform you of your mistake.

Hammonds start pretty much the same way, but there are two switches, one to start and one to run. You start you press and hold the start switch for a few seconds, then flip the "run" switch to the on position. After a few seconds more, you release the start switch, and once the tubes warm up, you're in business. If you press the start switch while the organ is running, you'll get a grinding noise; if you hold the start switch too long, you'll get a grinding noise.

What could be more simple?

How do I fix it?

First, be safe. Read up on the hidden dangers of old Hammonds above.

Be sure to take a look at the safety tips section of the excellent sci.electronics.repair FAQ for suggestions on how to avoid injury.

With these warnings in mind, you can take a look at the Owner's Service Suggestions for the Hammond Chord Organ on this site. The Service Suggestions basically cover testing tubes and tuning the instrument if it needs it. It also describes the "contact shifters" that can be used to correct individual notes or chord buttons that don't play.

The Service Suggestions were written for the original Model S, which used a lot of 6SN7 tubes. In later models, most of the 6SN7 tubes became 12AU7. Some 6SN7 tubes were replaced by other tube types. See the Hammond Chord Organ Tube Chart for details on the tubes used in models S-1, S-4, and S-6. You can still perform tube swapping as outlined in the Service Suggestions, just be sure you are swapping an 12AU7 with other 12AU7s in the later models.

In addition to the problems covered in the Service Suggestions, there are a number of problems brought on by the extreme age of Chord Organs. At this late date, a Chord Organ is almost sure to need a new power cord, as described above under "perils". And aside from tubes going bad, there are several other types of electrical aging that may prevent the instrument from working properly (or at all). Old resistors and capacitors may change in value over time. Solder connections tend to crumble, and other types of electrical connections tend to corrode.

Since Chord Organs have a open back, thick layers of dust, rodent nests, and who knows what else may also be interfering with proper and safe operation.

All these problems are fixable, of course. But know your limitations.

The HammondWiki site has some suggestions on where to buy tubes.

Where can I find music?

The original music books that came with a Chord Organ featured two styles of simplified sheet music. One was the somewhat bizarre tablature form called "picture music" developed by Hammond, with the notes of the song arranged in vertical columns under a small image of the keyboard. Kind of like trying to play piano by reading a piano roll. There were many books of Hammond Chord Organ arrangements published, but I don't think the tablature stuff lived past the original five volumes.

The other style of music for Chord Organ was pretty much standard "lead sheet" or "fake book" format, with just the melody and chord symbols. The only touches added were square notes to indicate the sharps or flats, and chord numbers to supplement the standard chord symbols. And of course, the arrangements were usually simplified to go easy on beginners and to compensate for the limitations of the instrument.

I've seen Chord Organ books for sale on eBay (search eBay for "chord organ"), but the good news is that any old music will do, pretty much. Most popular music books include at least the chord and melody. And there are lots of "fake books" which include only chords and melody. With the chord organ and a little rhythmic interpretation, that's all you need.

Unless you only read Chord Organ tablature....

What's this stuff?

Chord organs came with several small pieces which may have gotten lost over the decades.

Probably the most easily misplaced is the glass heel rest. You are supposed to rest your left heel on this item while playing the bass pedals, thus protecting your carpet. The heel rest is a molded glass disk about three inches in diameter, and comes to a point in the center. It looks kind of like an ashtray gone wrong. I'd include a picture, but guess what....

The other items that may get lost are the chord number slide and chord button caps. The chord number slide is a piece of plastic that slides over the chord symbols. The slide has numbers from one to six on it, with the two circled. There were six chord button caps which fit over the chord buttons. Four of the caps were numbered.

The slide and the chord button caps are supposed to work together with music arranged for chord organ, which includes a chord number along with chord symbols. Chord number 2 was always the major chord for the key the piece was in. So for a piece in the key of C, you'd slide the slide so that the circled two covered the "C" column, and place the "2" cap over the C major button. The "1" would go on F major, one column to the left, and the "3"column would go on G7, one column to the right of C major and two rows down. The "4" cap would go on D7, one column to the right of G7. Many songs would only need these four chords; the unnumbered caps are there for backup.

Check out the full description of the chord buttons for an illustration of the slide and buttons caps in action.