"Helicopter" noise coming out Hammond C3

[toto]

Hi everyone,

After opening and doing a bit of service on my c3 I have an issue and I can’t find a solution.

I get an “helicopter sound” coming out the AO28 output for the past few days. It is very bad when volume is full. This annoying sound is there even when the manuals are off, perc off and vibrato off….

Could it be the run motor or the vibrato scanner making that cyclic noise? I oiled the scanner few days ago and last night I could see that there was oil at the bottom of the run motor and scanner. Would that matter?

This Hammond is 110V and I live in Ireland (220v) so I installed this frequency converter but I never had problems with it. http://wiki.keyboardpartner.de/index..._mk3_(english)

My main output is Jack as I go to my Leslie 147 through a combo preamp. Doesn’t matter anyway as if I plug headphones straight out the Hammond, the noise is there.

Any ideas?

Thanks so much! :-)

[enor]

"Helicopter noise" is most probably scanner related. Take apart and rebuild!

[toto]

I Unplugged the scanner from the preamp (black wire) and the sound was gone so it's definitely the cause, thank you Enor. Then I took apart the scanner and rebuilt it but the noise still there. Ill do a deeper clean tonight I suppose. I haven't removed and cleaned the shaft with the cog and clutch on it.

[enor]

Is the little contact pin bent, maybe?

[toto]

I don't think so but I'll take a close look at it tonight. If it is what to do? straight it back?
I think i need a deeper clean as I used very hot water to clean brushes and screws etc.. Ill redo it fully with methylated spirit

[enor]

A bent pin will cause what you describe. Yes bending it back is the right thing to do, but it easily breaks and getting it 100% straight is very near impossible. The closer to straight you get though, the less the helicopter noise.

- - - Updated - - -

I used very hot water to clean brushes and screws etc.. Ill redo it fully with methylated spirit

Brushes?

The most important bits to get clean are the phenolic washers/insulators. Also make sure there's no metal "whiskers" inside the scanner.

[KC9UDX]

Twenty years ago I was in a band with a guy who played a transistorised Hammond. We ran a flanger on it. Every once in while the organ would oscillate at an inaudible frequency. With flange, it made a sound exactly like an airplane flying over, interrupting us. He'd yell "@#_* airplane!" and pound his fist on the cheek block, making the sound go away. So we wrote a hit song about a "&@## airplane". If only we'd had a helicopter noise.

[toto]

Ill check it, but if it bent, I don't know how as the helicopter noise appeared before I ever opened the scanner. Ill do a surgical clean and hope for the best.

[enor]

It can also be due to a shorted insulator, or a short in the vibrato switch box (under the drawbar base)

[toto]

Done, thank god!
It's been painful but after the second cleaning it worked. If anyone reads this, the best product to clean your scanner is gasoline. the oil goes away so easily with kitchen paper & a brush...
Unfortunately while servicing mine I broke the two 50 years old cotton threads right by the bearings, this sucks... I'll take it apart another time and do this. I had enough and the last thing I want to do this weekend is reopening that bloody scanner !
If anyone knows the easiest way to put new cotton threads back, you are more than welcome to tell me!

[David Anderson]

Done, thank god!
It's been painful but after the second cleaning it worked. If anyone reads this, the best product to clean your scanner is gasoline. the oil goes away so easily with kitchen paper & a brush...
Unfortunately while servicing mine I broke the two 50 years old cotton threads right by the bearings, this sucks... I'll take it apart another time and do this. I had enough and the last thing I want to do this weekend is reopening that god damn scanner !
If anyone knows the easiest way to put new cotton threads back, you are more than welcome to tell me!

In terms of the cleaning procedure, all this is well-known and has been discussed on this forum countless times. In the U.S., we often use naphtha (a cleaner solvent than gasoline), but don't know if you can buy that anymore in the EU, where so many things have been banned. In over 25 years of working on Hammonds, I have never heard of anyone cleaning a scanner with water. The point is not to remove the oil, which is itself completely non-conductive, but to remove any conductive particles stuck to the insulators in the oil.

I will re-post what I've posted before on to how replace the threads. If there is a good bit left, you can simply tie another thread to what's left.

How to rethread a scanner bearing.

Tools/Parts needed:

Strong thread (button thread works)
Scissors
Some very small gauge wire/inside of a garbage bag twist-tie
Hemostats or needle-nosed pliers
Magnifying glass, depending on your vision
Good light

1) Remove all the old thread. Often the loop around the bearing is intact, so you have to carefully cut the old thread with the end of a razor knife or some other such implement. I found that sharpening the end of a paper clip worked well. Don’t pull too hard when removing it since it can catch between the bearing and the flat springs.
2) Push the new thread in through the outside hole in the bearing. On the bearing closest to the motor, this will be on the motor side.
3) When you can see the thread between two of the copper-colored springs that hold the bearing in place, use the small gauge wire to fish it up between the springs till you can grab it with the hemostats.
4) Pull a generous length of thread through.
5) Leaving a large loop that you will use at the end to tie the knot, push the thread back through the gap you just fished it out of and towards the next gap. When you can see it, fish it up through the second gap, but make sure you leave the loop at the first gap.
6) Repeat the process till you’re back at the first gap, at which point there will be three sections of thread passing through that gap: the two ends of the loop around the bearing and the thread that will bring the oil into the bearing.
7) Make sure the thread is seated in the groove in the bearing.
8) Tie a square knot to hold the thread as tightly as you can around the bearing without breaking the thread.
9) Cut the excess thread from the free end.
10) Pull the leftover loop back through the bearing and tug gently to move the knot under the spring.
11) Cut the thread at the spool end leaving a generous amount to reach the oiling cup and wrap around the oil felt.

[alpine]

In terms of the cleaning procedure, all this is well-known and has been discussed on this forum countless times. In the U.S., we often use naphtha (a cleaner solvent than gasoline), but don't know if you can buy that anymore in the EU, where so many things have been banned. In over 25 years of working on Hammonds, I have never heard of anyone cleaning a scanner with water. The point is not to remove the oil, which is itself completely non-conductive, but to remove any conductive particles stuck to the insulators in the oil.

You can get naptha as lighter fluid still in the UK, certainly from Ebay UK, not sure if we have any tobacconists left...

[enor]

Certainly available in Sweden too, sold as "kemiskt ren bensin" which translates to "chemically clean benzine".

[toto]

Thanks for that guys!

[Bobmann]

Done, thank god!
It's been painful but after the second cleaning it worked. If anyone reads this, the best product to clean your scanner is gasoline. the oil goes away so easily with kitchen paper & a brush...
Unfortunately while servicing mine I broke the two 50 years old cotton threads right by the bearings, this sucks... I'll take it apart another time and do this. I had enough and the last thing I want to do this weekend is reopening that bloody scanner !
If anyone knows the easiest way to put new cotton threads back, you are more than welcome to tell me!

Personally, I would not use gasoline...too nasty, smelly and it takes too long to evaporate and leaves a residue.
I use Lacquer Thinner most of the time. Odorless Mineral spirits can be used as well, and is slightly less volitile. Both are available at most hardware or paint stores. Acetone is also easy to get around here, but it evaporates too fast and is just as volitile as Lacquer Thinner.
FWIW...soaking for long periods of time is really not necessary, unless there is a thick buildup of hardened varnish. The phenolic parts are not porous, so cleaning these is no different than cleaning a metal part. A rinse with the solvent of your choice is sufficient. I will pour a little solvent in a container with the parts, swish around, dump the solvent and repeat once. Parts are perfectly clean.

All these chemicals are pretty flammable, so caution should be used. Gasoline fumes travel a long way, and spark from a motor or pilot light will cause an explosion.

I have used some safer alternative degreasers on other things, but not a scanner yet. I started using a citrus based degreaser "PB Blaster" brand on drawbars with great success. I got a few cans off Amazon. It is not volitile, is biodegradeable, and sure smells better than lacquer thinner! It is also safe around all plastics. It does a great job getting rid of all that dried on grease that is found in many drawbar assemblies. I scrub it with a small brush, then rinse with hot water then blow off with compressed air. It comes out squeaky clean. It also takes off the grease on the metal part of the DB as well, and does not hurt the paint on the numbered part.

I plan to use this stuff on my next scanner rebuild, which is on the bench right now.

I know that there are many of the citrus based cleaners on the market, I would imagine that there are others that work as well as the PB Blaster.

Just my opinion...Bob