Unusual Problem, Hammond M3

[HMP22]

New member here, since I just cant seem to figure this one out.

Just a quick precursor to outlining this issue. I am completely new to this world of Hammond Organs. I will probably know what youre talking about but my nomenclature isnt perfect, nor is my comprehension of these machines very deep at all. Refer direct to paragraph 3 for the problem, the first 2 are just the things I did to the M3 during troubleshooting.

I picked up this 1958 Hammond M3 for 50$. Its clearly lived inside, and until I opened the dust cover off the TG, it shows no signs of tampering. The TG is well lubricated using genuine Hammond Generator oil. The various wires coming off the TG have been inspected at exhaustion for breaks or cracks. (None have been found)

All tubes have been pulled, and contacts cleaned. Socket and tube. The same can be said for the drawbars, speaker (EM 4 wire) and Generator leads. It starts easy and runs quietly.

I am loosing the tones "C" "F" and "A flat" To include the foot pedals, and in all octaves of both manuals.

C: Upper and Lower Manuals; When any white draw bar is pulled by itself, or with any combination of other white draw bars. (could be 1 could be all of them. doesnt matter)

F: Upper; When the 2nd brown drawbar, 1st and 3rd black drawbars are pulled. Alone, or in conjunction with each other. Lower; When the 1st and 3rd black drawbars are pulled. Together or alone.

A Flat: Upper; When the 2nd black drawbar is pulled . Lower; When the 2nd black drawbar is pulled.

The above are the ONLY times that those tones dont operate. However, the contact of the key being depressed can be heard though the speaker in all the above situations. Also of note, when the Lower 3rd and 4th WHITE drawbars are pulled, the top 2 octaves in tone "C" can be heard clearly, but they sound identical to each other, and incorrect. The same is true for the Upper when the 2nd, 3rd, and 4th WHITE drawbars are pulled. The top 3 octaves of "C" can be heard loudly and clearly, but all sound exactly the same, and incorrect. That is to say, that between B and D, the C sounds out of place.

Every function in the switch boards work flawlessly. To include percussion and vibrato.

The properly functioning aspects of this machine are loud, clear and predictable. The only problems I have noted are as I have outlined above. And again, I have not observed any broken wires nor do I hear ANY nasty sounds from the TG (Like a jammed wheel or something like that). I attempted the "hold the bad key down" while jiggling wires trick, and even tried furiously pressing the bad keys in the above outlined configurations. Contact is absolutely being made at the manuals. But I just cant get the right sounds out of them with those certain drawbar configurations.

Any direction or insight would be greatly appreciated, as I have run out of tests to perform, and feel like its something that can be easily diagnosed to the folks with alot of experience.

Thank You,

Hunter

[tpappano]

Hmmm, your symptoms sound a little odd, especially if a tone does not sound in any octave. One thing that I would do is first verify that all wheels are spinning. Prop up the rear edge of the generator about 2" or so with blocks of some sort. You can slide your hand under there palm side up and touch each wheel gently with a fingertip. There is a row of wheels across the front part of tg and across the rear part. You should also be able to verify that the spring clutches are free and working by pressing the wheel edge slightly. The wheel should stall and start spinning again when you release pressure. Don't touch the drive gears on the main shaft running down the center (ouch possibility), just the tone wheels. If a set of wheels was not spinning, it would not necessarily make any weird noises signaling the problem.

[Alek Z]

Yes as Tom said make sure all the wheels are spinning. I would also do some contact cleaning on the drawbars and check that all the drawbar wires are still soldered in place. I would also use some tone generator charts, and keyboard/drawbar frequency charts to potentionally narrow down your search for a loose wire/bad connection, which would most likely occur with the black insulated wires on top of the generator board that go to the manuals. Also check the generator terminals, this is where the giant cables attach to the upper and lower manuals from the generator. For the upper manual can be checked by unbolting the manuals and removing music rack base, then lifting up, where you will see all the connections coming from the generator. Lower manual is a bit easier, just unscrew the black metal plate covering it at an angle, and you'll see the same thing. This is am extremely strange problem if it is exactly as you have described, and would be one in a million so perhaps there is just some misunderstanding on your part? I'm really just throwing shots in the dark here because I don't believe there's one single thing to cause all these problems, and they are rather odd.

To sum up what I'm saying, do what Tom said, check that wheels are spinning, then do some cleaning on the drawbar contacts, go back and double check specific tonewheel circuits (just look online for a service manual pdf, finding which tonewheels go to which tone is pretty easy), and then check your manual terminals. Hopefully the problem will reveal itself at one of these points.

[bourniplus]

I don't fully understand the OP's description, but it looks like it could be only one missing "C". (F, Ab and C have it in common). It would then probably be a bad solder joint on the TG.

[Alek Z]

This wouldn't explain how it's in all octaves though... Maybe he just means that with each higher harmonic, going lower down the keyboard by the octave it still doesn't work? That would make a lot more sense, and probably would be at the generator since it's in both manuals. Though they also don't work in the foot pedals which is extremely strange because that uses a whole different designated octave of tonewheels (which is why it sounds different). Different drawbar and contacts too. Basically it's an incredible coincidence if the same tones aren't working in the foot pedals, due to being completely isolated from the rest of the systems.

[HMP22]

Alek Z,

You are on the same page, and understanding the strange nature of the problem.

[HMP22]

UPDATE:

I have lifted the TG, and discovered 73, 49, 61, 44 wheels are NOT spinning. To include the gears.

[HMP22]

THE FIX:

Alright, so first and foremost, thank you for the replies. It got me to unbolt the TG and lift it up, to discover the 8 tonewheels not spinning (4 gear sets). The cause, was one if the brass keepers holding the last piece of the shaft in place, had popped off, allowing the last section of shaft to shift far enough towards the starter to disengage the gears of those tonewheels. Once I secured the shaft in the intended place, re-engaging the cog wheels, everything on the M3 works great!


The more you know....

Thanks again!

[tpappano]

Well done! You've just earned your first tone generator ‘merit badge ‘ 8)