Help with AC motors spinnning slow in Leslie tremolo unit

Thread Starter

Mettleramiel

Joined Aug 10, 2022
5
Hello! I have a tremolo unit out of an electronic organ. The unit has 2 AC motors stacked on top of one another. When I apply mains voltage to them, they spin incredibly slow, maybe 10 rpm where it should be something like 10 times that. The labels on both motors read "117 volts 50/60 htz" and my meter is reading 120v going in.

The motors ran at full speed before removing it from the organ. Does anyone have any ideas as to where to start? Thanks.
 

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LowQCab

Joined Nov 6, 2012
4,029
I would tend to doubt that the "Shaded-Pole" Motor in the picture is an original part of the Speaker
because the rotating baffles are variable-speed,
and are expected to be able to change RPM rather quickly.
A small Shaded-Pole Motor just isn't powerful enough to quickly change the Speed,
and provide a reasonable Braking-Action to the Rotating-Baffles.

The Motors are not designed to run on direct AC-Mains-Power.
They are supposed to be driven by Circuitry inside the Organ.

There may also be problems caused by Belt-Slippage.
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Last edited:

MaxHeadRoom

Joined Jul 18, 2013
28,619
I suspected they were shaded pole motors at first glance, also the shading ring appears to be visible on the left side laminations. close to the rotor.?
 

Thread Starter

Mettleramiel

Joined Aug 10, 2022
5
The motors are clean and spin freely. No slippage.

Running the motors individually, the small motor runs the baffle at the slow speed while the large motor will not spin the baffle at all.

I removed the small motor and the unit runs full speed with just the large motor. I actually have 2 of these units and the function the same.

Since the small motor is friction running a rubber rimmed disk attached to the large motor, I'm guessing that the controls start the large motor with the small one? Who knows, but it's working like I want it to now
 

shortbus

Joined Sep 30, 2009
10,045
I would tend to doubt that the "Shaded-Pole" Motor in the picture is an original part of the Speaker
because the rotating baffles are variable-speed,
Is that an assumption due to your experience with a Leslie? Not all Leslie speakers were variable speed. Some like the on the TS has were two speed, high and low, no variable at all.
 

shortbus

Joined Sep 30, 2009
10,045
My bad .....
I never heard of a "2-Speed" Leslie until now.
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I told you in an earlier thread that they were originally made as single or dual speed -
Models
Single speed
The initial models of Leslie speakers did not have the "chorale" setting. The control switch was simply a choice between "off" and "tremolo". The first model of Leslie produced was the 30A. It emulated Hammond's DXR-20 tone cabinet, which used moving drums but only produced amplitude modulation, not frequency modulation. It contained a 15-inch (380 mm) drum and the power amplifier was housed in the top of the unit, to allow easy repair.[26] This was superseded between 1947 and 1949 by the 31H, also known as the "Tall Boy". It was similar in appearance to the 30A, but contained additional louvres along the top of the cabinet. Also, reflectors were placed on the end of the horn, to allow the treble signal to exit the unit through the sides, rather than on the top.[27]

The next models Leslie produced were the 21H and the 22H, which had a cabinet in a similar styling to the better known 122, with the same dimensions and louvres. They were powered by a 40 watt tube amplifier.[28]

Dual speed


A Leslie 122 speaker

The 122 is the most popular Leslie. It was specifically designed for the Hammond organ and is the model most commonly identified with it. It is 41 inches (1,000 mm) high, contains separate motors for chorale and tremolo, and a 40 watt tube amplifier. The 122 is the most adaptable to being recorded, as it has a balanced signal which eliminates mains hum and other noise.[29] The 122RV was the same model, but with an additional reverb amplifier, which fed through to a separate static speaker.[30] A slightly smaller version, the 33-inch (840 mm) 142 was available.[31] Hammond-Suzuki currently manufacture the 122A, a straight reissue of the 122, and the 122XB, which contains a modern 11-pin adapter, an IECC mains adaptor, line-in, and a jack socket for a footswitch to control the speed. This eliminates the need for a combo preamp.[32]

The 147 is the "universal" version of the 122, designed for many organs, and has a different amplifier input and motor speed control, but is otherwise identical.[33] The signal input is unbalanced, allowing a simpler connection to organs that have a built-in speaker system, such as the Hammond A100, or a Wurlitzer. The motor speed switching uses a separate AC signal, rather than the DC voltage control of the 122. In operation, the noticeable differences between the 122 and the 147 are the 122's lower susceptibility to induced noise, and a delay between operation of the speed control and the actual change in speed. As with the 122 and 142, the 145 is identical to the 147, except that it is housed in a 33-inch (840 mm) cabinet, and thus slightly easier to move.[34] As with the 122, Hammond-Suzuki manufactures a modern replacement, the 147A.[35] The model X-77, released in 1968, was designed to accompany Hammond's new tonewheel / transistor organ, the X-66. It contained seven different tab controls and six speakers. It has a completely different interface from other Leslies, using a 12-pin amphenol connector.[36]

Above from - https://en.wikipedia.org/wiki/Leslie_speaker#Models
 
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