03 October, 2014

SUH DER SD83-A AC Synchronous Motor Teardown

In an earlier blog post I did a teardown of a TYC synchronous motor.  We found that it was made of entirely plastic gears and was a little lacking in the quality.

Today I received a new batch of SUH DER SD83-A synchronous motors.  I purchased them directly from the manufacturer in Taiwan.  I also had an immediate need to replace a faulty one.

What follows is the teardown of the faulty motor.  The motor itself and its gears were all in perfect condition.  Its not pictured, but the failure occurred due to dirt and dust getting caught between the motor output shaft and the bushing on the front of the motor.

The bushing is pressed into the front metal panel of the motor.  In my case, when the output shaft had seized against the bushing, the bushing itself started to turn.  So the motor still worked.  That is, until the hole in the front panel of the motor became unevenly worn and the motor could then seize up again.

You may notice evidence of tampering to the motor in the picture below.  I had opened this motor previously in order to get it going again.  Brute force was involved, and it did work again, but it was time to find a new motor.

Let the teardown begin!

Motor with front cover removed.  We can see a mix of plastic and brass gears.  The large plastic gear appears to have a steel gear that mates with the brass gear.  It seems they have decided that plastic gears are good enough for the low torque part of the motor:

Close up of the output shaft gear.  It looks like a brass gear with the steel output shaft pressed into it:

All gears have been removed, the motor output shaft is seen here, along with its plastic gear:

Metal cover removed.  The metal cover is pressed into the exterior motor housing:

Close up of the motor's rotor:

Motor stator (the purple thing - it contains the winding for the motor) and the remaining shell that the stator was sitting in:

Motor stator, insulating tape still installed:

Motor stator, insulation tape removed.  Beneath the wires appears to be masking tape:

All of the bits and pieces that made up the motor:

You can compare the construction of this motor with a cheap eBay motor here:

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  1. Thanks Robert for the interesting blog.
    I am after a new 24VAC SD83 synchronous motor that is in my evaporation air conditioner. I took it apart and it is corroded and hence seized up.
    Please can you tell me where there can be purchased from in Australia or overseas.
    Thanks for any help, regards Matt

    1. Hi Matt,

      I can't get them anymore as the company that makes them is only interested in large orders now and I don't know of anywhere else that they can be purchased.

      I tried a metal-geared 1.8RPM TYC branded motor, but even that wasn't up to the job. It seemed to lack the required torque.


  2. hi robert can you get hold of sd83-a 30/36 rpm it runs a cobo disco light it works the one in it but it doesnt run as smooth

    1. Sorry, I can't get the motors. The company that makes them isn't interested in selling small quantities anymore.

  3. Hi is this a bidirectional (CW and CWW Motor

    1. Yes, it was a CW/CCW (bi-directional) motor.



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