The Hammond B3000 organ

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My father and his brother were passionate organ players, and in the1960's, electronic organs were 'the' thing to have. Everybody had organ music records at home, mostly Hammond, with 'happy sound' dance music. It was the times when modern life, as we know it today, began. So we had color TV, cars, nice holidays, and people enjoyed being together on parties. The sound of electronic organ was accompanying these times. Who could afford it, had a real electronic organ at home.

B3 vs B3000. Today, unless it's a Hammond, old electronic organs are impossible to sell. People give them for free, trying to find a good home for Daddies good old instrument, rather then have it destructed. The "budget" style Hammond Tone wheel organs, so the ones with not two full manuals, are sold "as is" for just a few hundred Euro. Some famous songs, everybody knows, were created on such. They have a cleaner sound, which at the time was preferred. The B3 is an older design, and sound is less clean. . However every year they became more expensive to build, and the coming of integrated digital circuits made it possible to create a digital version of it. That was also needed for the Hammond company, to deal with competitive organs, which offered a much wider range of electronic features, such as sustain, arpeggio, and a rhythm section.

Older Hammond organs are enough for sale, but people want the top models. With the top models it's the opposite. With those, If a buyer doesn't want to pay the price, there is always another who will. A good B3 costs now well over 10.000 Euro, while I write this in 2024. In terms of value, that is still less as what they cost when new.

The electronic B3000 was the predecessor of the B3. It looks almost the same, and luckily, they did not stuff it with Gimmicks. This is the nice part of the B3000. So yes it's electronic, but you have the B3 feeling still. From the old Hammond catalog, you can read the intentions: It has no serviceable parts. Some features were added, which would have been nice to have on a B3, but technically too difficult. Such as a string pedal. So B3000 had these painfully missing things. They could not resist adding a piano tone to it, and en electronic piano tone, but that was the only "modern" thing they added. For the rest, at a first glance, you would hardly see the difference. B3000 was also used as stage organ by professionals. Roda Scott played the B3000 for many years. Also Barbara Dennerlein who is a hard core tone wheel player, still performed on the B3000 occasionally.

As the B3000 began to enter the second hand market, in the 1980's, they were above my budget at the time, and almost none were for sale. I was at home at the Dutch Hammond importer, who wanted to sell a white B3000, owned by his wife. It was around 1990, but he wanted 6000 Euro for it. Later, second hand prices got lower, and I bought mine. Still not cheap, but I could do it. I still own this organ today, but I probably will sell it in the near future.

Contents

Working Principle

Features, compared to B3

Sound of the B3000

Quality of the B3000

Problems with my B3000

Repairs

Working principle

The B3000 works without the famous tone wheels, but many elements of the old principle were kept. It still features a tone generator, which is a unit where all tones are present, and are swiched to the amplifier when a key is pressed. This tone generator uses special ICs, made on Hammond specifications. These IC's scan the keyboard. At the same time, Inside each IC, a certain number of frequencies is generated, while the IC connects only specific tones to the outside, when a keys are pressed. This is not so different from a tone wheel organ,

A main difference is, the tones are all generated and processed as square waves, until finally, all at the end of the chain, the sine waves are extracted from by means of a filter array. This filter just rejects the harmonic which don't belong to the tone., and the analog sound appears. Analog electronic organs were made by other companies, but Hammond chose the digital method. So yes, it's a digital organ, but not as you may expect. The tones are not processed as digital 8 bit or 16 bit words, and there are no A/D converters or microprocessor used. Inside,it works fully discrete, you can follow the signal everywhere.

Hammond called the solid state organs 'LSI' technology. Which was just a marketing name, because one way or another they had to sell it as something 'better'. They picked that name from the digital ICs used, but these were just normal gates, and counters, etc. which were made with 'Large Scale Integration'. Really only marketing BS, but as Hammond used the word LSI so much, the sound of those organs became referred to as LSI sound. What people mean by that, is the cleaner sound, as some of the imperfections of the tone wheel generator were eliminated. However the main imperfection, the key-click, was added with a random noise generator. In very short wordings, and very incomplete, this describes the B3000. More details are below here.

Hammon B3000 organ.

In 1992, I bought this Hammond B3000 organ, from a person living near by here. The organ was only 12 years old at the time, and worked perfectly. By coincidence, one year later, I found a newspaper add, from the USA, offering schematic copies for cash. This was in an international "free adds" newspaper. That worked well, before the internet. I think today, you should not try this, but after sending 17 US$ in an envelope, a few weeks later, a mint quality copy of the service manual was in my mail box, send by John Drodos from the USA. It had those 1 meter size schematics. So he had access to a very professional copier. Always good to have, but i did not need it, until now, in 2024, when I decided to give the electronics a general inspection.

Before that, in 1994 I build a Doepfer midi interface inside, which was quite expensive, because it had to be custom programmed by Doepfer for the number of keys of each manuals, and the pedals. For the pedals, I needed to make myself an interface from the negative voltage of those, to the positive voltage of the midi interface. That had to to with the string bass circuit of the pedals. For the manuals, I could use the original key contacts itself, which made it a lot easier for me. The drawback was, it is not a dynamic midi in this case, but I chose for this option still, not having to add additional two-pole contacts to every key.

I build it in, in such a way, doing smallest modification to the internals, and removal would be not difficult, and leave little traces. The Doepfer "MONA" unit, is none SMD, made of standard IC's, all of which can still be found. The only custom part is the EEPROM, which has the MONA program, and the individual settings inside. So unless I damage the EEPROM, this unit is always repairable.

As the organ aged, I had contact problems with the connector for the Reverb, but wiping those off, fixed the problem. I played it not very often, but every time I played it, the drawbars were scratchy. This could be fixed by exercising them a little bit. The drawbars can be opened quite easily for service, just take off the cable, remove the little black screw, and you can pull out the arm, to clean the silver contact. As easy as that, and only needed when you play the organ not so often. That worked fine for me.

Then, around 2020, the organ was 40 years old be then, small problems began to accumulate. All of them not looking not very serious. Kind of nasty was the missing key click on the top manual, which makes the sound kind of dull. It looked like only contact problems, but some others came to it. So I decided to try fix them, and I will show the results here.

B3000 Features added, compared to the B3.

Sound of the B3000

Sound is a lot like the B3 of course, as it was the Solid State replacement of it. As long as you play the B3000 same as the B3, it sounds the same, but the sound is less distorted.

Hard core nostalgic sound lovers, prefer the Leslie 122. For them there is nothing like it. The Leslie 147 has a somewhat cleaner sound. These are one-channel Leslies. The HL722 is a four channel, 11 pin Leslie, which is beautifully integrated in the B3000. This is a major difference with the B3, which uses a one channel leslie. . .

The tube Leslies from the days of B3, are loud enough for the living room, but at the stage a bit more loudness would be good. The HL722 Leslie of the B3000 has a lot more power. It's just the same as the very popular HL822, which is a black color stage model of it. The HL722 has also separate tone control at the side, for the Leslie and non-Leslie speakers, which is really something nice. It's a wonderful Leslie, which can play soft and gentle, or also very loud with amazing deep bass, and it can really "bite" when you play it aggressive. It is know that music amplifiers have a specific coloring of the signal, and also some distortion on purpose. The amplifiers are made with Germanium transistors, which by nature have more distortion as silicon. The output is a transformer less Push-Pull stage without feedback. This means you drive it into distortion at full power. It is driven by a single ended transformer stage, which add some even harmonics. Prices of NOS Germanium transistors are soaring, because the Guitar amplifier industry has discovered them, but they are still easy to find. Besides, I never had any bad Germanium transistors in my old collectors equipment anyway, it's rather very old silicon which gives me sometimes head aches.

What also contributes to better sound is a separate pedal amplifier, which does not use the rotating bass drum.

All in all, the B3000 sounds more modern as the B3, not lacking the high frequencies as much. Which for me is a bit of a disadvantage with the B3. At full signal the B3000 is exceptionally loud. The lowest frequencies are produced much tighter, more natural, not as muddy as the B3. This can be heard from the much better pedal sound, and also when using the "bright sound" draw bars, which are not just brighter, but the lower keys of these drawbars have a much deeper bass sound, which is really impressing. These "bright sound" drawbars seem to me made for church music, they are also nice for playing Bach. It is like an equalizer is in between, with the lowest frequency sliders set higher. Indeed the B3 has an equalizer build in. Many people do not know this, it is an huge section of resistors, as large as the whole keyboard itself, made of factory selected resistor wire, which is hidden underneath and inside the manuals. There is no way to see this, other than taking the manuals apart. In the B3000, they have put this function inside the ICs. So you can't "see" it, but it is present, you may call it a frequency curve. You can hear it when you use only one single drawbar, and then look at the volume of each key. Best way with an oscilloscope or AC voltmeter. At the lower keys the volume goes up. The normal "B3-like" drawbars, have the nature of the B3.

I have to say it, the pedal sound of the B3 is not very good. Pedal sound of B3000 is a lot better, and also it has a sustain on it, giving it more a string bass effect.

The head phone sound is pleasant, because the build in Reverb of the B3000 works also on the head phone. (You don't depend on the reverb of the Leslie, as with a B3)

Quality of the B3000

The case and the wood are well done. Not as heavy as the B3, but that is better for my back. At the inside, cheaper wood is used. You can see they are knocked together by factory people with little passion for their work, though you can also see (some...) of the design engineers tried to to a good job. But it ends up with a bit "patchy" result still. The PCBs are mounted sloppy, but fair enough, it works, and they don't come loose. There are quite some negative things to say, but in the internet people always talk about this first. I found also a lot of good things, such as the very nice quality of the key contacts, engraved lettering on the switches, and the use of silver contacts for the drawbars. Despite the contact problems the older connectors, their base quality is excellent, and they can easily be repaired. Also after 40 years, you can't really complain. A lot of electronics of the 70's needs a general overhaul today. Some day in the future, problems will add up, and at some point you stop repairing them, and only look at them as collectibles from the past.

Bascially the B3000 suffers of these problems today:

  1. Bad Electrolytic capacitors. I found a few. You need a high voltage capacitor tester. If you don't have one, better replace them all, because they are not many. Such a Chinese ESR tester is nice, but it won't tell you if they have leakge at high voltage. If you insist on using only an ESR tester, replace such which have higher than normal value. Such are not "better". These have leakage at high voltage.
  2. Connector problems. This needs a general overhaul. You need to do all of them, and it's not just a matter of quickly spray deoxit on them.
  3. Bad solder joints. Some are really weird, very very bad factory work. This needs careful judgement and good eyes. You can't leave half-bad work in. That will cause more trouble, if not already. On the other hand you should not damage items or PCBs by too hot soldering, or cause shorts you did not have before.
  4. Defective custom made ICs. Very bad when that happens.

On the forums I read, that older B3000 are not so ideal for stage work, because all the carrying around seems to trigger problems with the connectors. Apart from that is very nice for stage work, because of reduced weight, and the very good Leslie. For years it was the standard stage organ of Roda Scott.

Click here for Barbara Dennerlein, playing the B3000.

Problems with my B3000

When opening the organ, it looks like seeking a needle in a haystack. You can't just 'see' where problems are located, It was extremely confusing in the beginning, but later I found out, it is not so bad at all.

Here is a video of the inside The flat band cable, and the spiral cable, are not original, these are from the midi I build in. For the rest, the organ and it's dust are as it was originally. I am glad, mine has the optional dust cover. Otherwise, the keyboard would be filled with dust and dirt of 40 years. I am pretty sure, this would have dome more damage to the contacts.

Working principle of the B3000

Let me tell you first, I have not fully found this out completely, but let me tell you what I do know.

B3000 was the new flagship product, succeeding the B3. Interesting is the love-hate relationship of Laurens Hammond and Donald Leslie. As Leslie introduced his first Leslie Cabinet to Hammond, he was send away. Hammond said, it was an unserious item, such a thing we don't need here. So Leslie started is own company. The combination was the best thing of course. But Hammond was fighting against it, and forbid his dealers to sell Leslie cabinets. Also he used incompatible connectors on purpose. But Leslie cabinets were so popular, it could not be stopped any more. Then, Hammond tried to buy Leslie, but Donald Leslie said no. The B3000 is one of the very few models, were Hammond had fully surrendered. So the Leslie cabinet was sold in combination, with the Leslie brand name on it. Just as Leslie proposed it initially.

I will not and can not explain the working principle here in detail, because I know not enough about this. What I can say, the organ has same resemblance with the analog architecture of the B3. So like the B3, there is this whole array of tones which is generated, and the drawbars picking up the higher harmonics and sub-tones, of each keynote played, same as in the B3. Only difference is, the tones are..... square waves. So they can process all tones simply digital. Using CMOS digital ICs.

So the signal comes out as a square wave, but how is that solved? Well they pass the signal through a band filter, letting the 3rd. harmonic pass, but not the 4th. any more. So suppose the square wave sound of the lowest key is passed through this filter, all unwanted higher harmonics are gone, and lower than 1-sub harmonics gets rejected too. So there is no hum possible. It just can't pass, even if there was any. Now, the next higher key, is only 1/2 of a note higher (which is just 5% more frequency) , and it's signal can be passed through the same filter, and so is the next key and a few more. A whole group of keys can be passed, until the tone becomes too high, and then the next higher sine filter is used. By this system, not many filters are needed, and the whole filter unit for one manual fits on a 12x12cm PCB.

The key click is added with a noise generator, and things like chorus and vibrato is added as well.

There are many small and large PCBs inside, and lots of cables too. Luckily no flat band cables. The hardware is reasonably good accessible, even though some PCBs are stacked. There is a good writing on the PCBs, and connectors come off easily.

 

 

REPAIRS

REVERB BOARD was dead.
02-Nov-2014. Contacts at the bottom (PCB connector) were dirty. I had to clean those 2 times before already. This makes the whole reverb fail. Cleaning did the job. So that went fast. Later, I will re-plate the contacts of the PCB with new tin.
DRAWBAR unit exceptionally scratchy.
2-Nov-2024. Drawbar Unit of "Bright Sound" cleaned. This is a special section, with a Church Organ kind of sound, same as the cheaper organs had in those days. That sound is a bit scratchy, like the Philips Philicorda, and sure not jazzy, as the normal Hammond sound. I guess Hammond did not want to miss piece of the church organ market. Given, you play Bach, or Church music, it sounds quite nice even, and lower tones have a deep, very impressing bass, much more as the normal drawbars.

The whole drawbar was removed, because almost nothing worked any more. Resistors inside, on the drawbars itself are 820 Ohm +/- 10%. Some were 15% above, some were still good. 4 resistors were replaced. I wonder why they put cheap carbon resistors in there, because they have a tendency to go up in value.

Contacts were black and dirty. The (silver?) bars were still clean. It seems the contact bars were factory lubricated some light brown stuff.

There was lubricant in the sliders too, which has become sticky. Underneath the copper parts was oil, perhaps somebody sprayed some oil inside. So I decided to clean the whole unit, and took it completely apart. I lubricated the sliders very thin with silicone. The silver contacts were not lubricated. I think silver on silver is self cleaning, if no lubricant is used. The screws of the slide contacts were tightened very light, to prevent breakage of the plastic part. The screws were secured with "soft" (blue) screw securing fluid. The unit works again, but contact quality is still not as good as I want it. I will look at this later, but for now the unit works, and other things come first.

Demultiplexer (Demux) Board

02-nov-2024. I just suspect this board fop failures. I have to admit, I do not fully understand how this board works, but I have some imagination of what that might be. With the mess I found with this board, I am glad I repaired that for as far as I could see things are bad. It t did not fix the failures with the B3000 though.

When looking at it, I noticed white particles were crumbling from it's bottom side, falling on the next lower board. That same stuff as a leaking battery. So I decided to take the board out. I was afraid of removing such a stacked board for the first time, but I understood later this was badly needed anyway, not hard to do, and risk of collateral damage is low when I am careful. This ended up later, with taking each and every board out, just looking for bad parts, and the many factory soldering errors.

The white powder came from bad capacitors. There are seven 4700uF 6.3V on the Board. White particles and orange stuff comes out, along the wires. I took out the capacitors. All seven of them were bad. Capacitance was still ok, but leakage starts to go above 10mA at 4V. Which is a total defect, and it would not go away by re forming. The leaking capacitors caused quite some stains om the PCB, but I could remove that very well.

Why did that happen to ALL SEVEN of them? That is strange. When looking in the schematic, I saw immediately what damaged them. This is a design mistake. These capacitors can not charge up higher than 0.7V, because the base-emitter junction of the transistors they are connected to, will not allow higher voltage. That is not going to work with electrolytics, because you need to operate then above the voltage needed for the REDOX reaction, which maintains and re builds the isolation layer. I can not tell you this voltage, but it's lot higher than 0.7V. Basically these capacitors are in a storage (shelf) condition ever since. Using them, when playing the organ, at 0.7V, occasionally doesn't change anything. The effect was the usual, as I tested them. They are 10V types, capacitance was still ok, but the maximum voltage possible was only 3V, above that they began to draw a lot of current, but also below that, current did not go to zero. You will see the same with even NOS capacitors which are decades old. Such are often not defective at all, just need a re forming. In this case here, there was some orange fluid leaking out, indicating damage. I replace such anyway, but I tried to re form them, just as an experiment, which did not work. I could get them up to 6V, but it stopped there. I opened one up, and unrolled the foil. The foil was still wet and looking normal.

The two other Electrolytics on the DEMUX board were perfect quality, I left those in.

Bad solder joints

At the PCB bottom, I noticed many bad solder joints. They look like "just ok", but when re soldering them, the solder would creep off the wire, and refuse to wet it. Definitely a cold solder joint. I found many such. The PCB itself, though single sided and no through hole metallization, seems reasonable good quality.

Another issue with the DEMUX board is the space holders. These were at some day in 1980, made of soft, transparent material. Like 15mm pieces cut off some plastic hose. However this material is producing some sticky substance at the inside. This substance feels like glue, and it oxidizes the pins of the connector. Inside is some stuff, colored with green oxide.

Luckily, the green stuff resolves in isopropyl Alcohol. This is to my opinion a time bomb, and if you want to preserve your B3000, all of these space holders should be replaced. It's not just some greasy stuff, but it corrodes the connector pins too.

For now, this is all I am going to do to the DEMUX board. In a few days new capacitors will arrive here, and I can see if the board works again.

4-Nov-2024 . Here is a little error with the schematic too.

I am not a fan of analog pulse shaping, combined with digital ICs. But so far it seems to work. The 555 timer would have been a much better choice, and less parts too.

The defective capacitors in there are C1...C7. So all of it comes together here :) Am error in the drawing, and electrical design error, and defective capacitors.

After replacing the capacitors, the organ showed the same errors as before. No change so far. So the error must be somewhere else.

As a next step, I will take large sandwich construction apart, to clean all the connectors. This is such a weird item. It consist of three layers, stacked together, with long pins, which are like a data bus. The top layer is the DEMUX Board and TRANSPOSER Board. Here you see on the middle layer, one of the connectors to the Transposer board. Everywhere I find those space holders which are sweating some oily stuff, which makes the metal pins rusty, and green. This aggressive oil has also creeped underneath the connectors. So probably I need to remove those, for cleaning.

This is the bottom of the middle layer. As you can see, they drilled the PCB from the wrong side, then these things happen. So these little "caps" remained. Untouched since 40 years. I found 10 of those. A company which let's such stupidities pass, just deserves the problems they ran into.

.

Here are the same caps, they just fell off only by touching them. They would fallen somewhere into this sandwich, and cause intermittent PCB shorts there.

With regards of the Hammond soldering department :)

The Output Board.

11-Nov-2024. I still have no clue why so may functions of this organ fail. I may be more lucky perhaps, following the analog signal paths on this board. Like the Vibrato Delay is not working, and it begins with the Vibrato Delay switch here, which is connected to this board. This board at least if fully repairable, witch the exception of one strange 16 pin IC. For the rest, it's all normal parts.

Electrolytic Capacitors: 50% of them were "so so". At the end of life, capacitance tends to go up, while at the same time the maximum isolation can not fully be achieved any more, and there is some small electrical leakage, while ESR is kind of reasonable still. Such need to be replaced of course, but circuits often works still well on those, and replacing them does not repair a faulty PCB. It's just preventive maintenance in such a case. I will put back in the original capacitors when the test fully ok, like new. That was the other 50%,

Transistors: All tested, no bad one found