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50 Hz noise from Leslie Motors

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  • 50 Hz noise from Leslie Motors

    Hello
    I have a VERY annoying hum coming from my Leslie 145 made in England, 230 V AC.
    The noise is a Ab1 note, around 50 Hz. The leslie is positioned at 3 feet distance from the "high keys" side of my B3. In any case, the noise is heard also after switching the Hammond off (the Leslie has its own Power supply cable, going to the italian 220 V AC 50 Hz (!), so it can be used also with other instruments by a line in jack... When I pull the 4 motor plugs off the sockets in the amplifier, the noise heard in the large speaker is very very low, really acceptable.
    When I connect the motors, it becomes too loud for the small room where I play... On the lower motor it is written 117 V AC 60 Hz, so the motors take the AC voltage from the Ampli, although it is 230 V.
    BTW: the ampli has been recapped, yes, and both the motors overhauled by a skilled tech who changed all the worn mechanical components.
    Any suggestion about where to begin from, in order to find a solution?
    Grazie mille :-)

    Fernando

    - - - Updated - - -

    I forgot to say, I am located in Italy , 230 V 50 Hz AC...

  • #2
    Originally posted by Fernando View Post
    Hello
    On the lower motor it is written 117 V AC 60 Hz, so the motors take the AC voltage from the Ampli, although it is 230 V.
    Hello,

    You have to clarify this point.

    A 110 Volts motor powered on 230 Watts will growl, over heat, and smoke quickly.

    May be the amplifier had been modified to supply 110 Volts to the motors.

    You can check it using an incandescent Lamp of 60W/230V with two solid wires.
    Plug it into the motor socket and check voltage : 230 V 110 V or other. If you don't have a meter the light intensity is a good indication

    JP

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    • #3
      Originally posted by Jyvoipabo View Post
      Hello,

      You have to clarify this point.

      A 110 Volts motor powered on 230 Watts will growl, over heat, and smoke quickly.

      May be the amplifier had been modified to supply 110 Volts to the motors.

      You can check it using an incandescent Lamp of 60W/230V with two solid wires.
      Plug it into the motor socket and check voltage : 230 V 110 V or other. If you don't have a meter the light intensity is a good indication

      JP
      UK built Leslie 145s and 147s are designed run on 230/240V but will supply 117V to the motors, so no modification would have been done for this. Check anyway, but that should not be the problem.
      It's not what you play. It's not how you play. It's the fact that you're playing that counts.

      New website now live - www.andrew-gilbert.com

      Current instruments: Roland Atelier AT900 Platinum Edition, Yamaha Genos, Yamaha PSR-S970, Kawai K1m
      Retired Organs: Lots! Kawai SR6 x 2, Hammond L122, T402, T500 x 2, X5. Conn Martinique and 652. Gulbransen 2102 Pacemaker. Kimball Temptation.
      Retired Leslies, 147, 145 x 2, 760 x 2, 710, 415 x 2.
      Retired synths: Korg 700, Roland SH1000, Jen Superstringer, Kawai S100F, Kawai S100P, Kawai K1

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      • #4
        In your case, it is tricky to test the motors "out of the box" or with something other than the amp.

        I would probe the motor sockets of the amp with a voltmeter to confirm that it's putting out around 120V to the motors at most.

        Worn motor bearings usually don't create a "hum" sound, it's more of a repetitive "grinding" sound if that was the problem. I would be suspicious of the grommets that mount the motors to the cabinet. It's possible that one of the wing nuts is over-tightened which may have "squished" the rubber grommet too far and caused direct contact with the motor and wood cabinet.

        Does the noise occur on slow, fast, or both?

        Comment


        • #5
          Thanks for the replies and sorry for the delay... I had a flu :-(
          I tested the voltage coming to the motors (that had been overhauled...) and it's 112 V
          I connected the motors to a 220 to 110 V AC converter, instead of the amplifier's sockets: same noise.
          Honestly, I guess it's a mechanical noise amplified by the wood. The problem is, the rubber grommets were replaced 5 yrs ago... They could be bad, but how to test this?

          Comment


          • #6
            If the grommets are relatively soft, keep them.

            A motor by itself should not be that loud. Some hum is expected by virtue of the field coil of the motor resonating, but a very loud 50Hz hum might be an indication of faulty motors.

            This could also be normal. I have noticed that today's replacement motors are significantly louder (mostly in field coil hum noise) than the original Leslie motors are. Did the previous tech replace your motors rather than lube / rebuild them?
            Last edited by muckelroy; 02-08-2018, 12:48 PM.

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            • #7
              No, I suppose the motors were overhauled. The problem is, the "hum" increases to the (annoying) top when in the "fast" status. I am tempted with buying a new motor (110 V is not difficult to find...) or, due to the small room I am playing in, I shall sell it. Reluctantly, because the sound is TOP

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              • #8
                BTW The Leslie has no wheels/pads under the cabinet. I mean, its lower wood panel touches the ground, and it's located in a mezzanine... Is it suggested to put some wheels/ pads under the beast to lower the noise? At the moment neither does it have rubber feet...

                Comment


                • #9
                  It is certainly possible that the Leslie cabinet is resonating through your floor. It's hard to know without seeing / hearing this hum in person. A pad underneath the Leslie could help if that is the case.

                  Every Leslie has a certain amount of motor hum that is unavoidable, so hard to say if the hum you experience is within spec or not.

                  Comment


                  • #10
                    Use the 112V supplies. That's well within range of what the motors require, and it's unrelated to your issue.

                    The amplifier having been overhauled and capacitors replaced is no guarantee that it's not causing your issue.

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                    • #11
                      Thanks
                      I shall try padding the Leslie ... let's see what happens

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