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LaSanMarco SM90 Smoke ... Sparks etc

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  • LaSanMarco SM90 Smoke ... Sparks etc

    Just had some problems with my LM90 ... start to go very slow the other day then stopped completely! Wasnt sure what was happening so pulled the bottom off to have a look. Didnt smell the burning electric motor smell so that was a good start.

    Pulled the capacitor off and tried to run it again and it seemed to run OK, slow to get going and speed up but then good. So got a new capacitor (450V 10uF) from CoffeeParts. Replaced the capacitor tonight and was ready to go.

    Flicked the switch ... started to spin ... BANG ... smoke ... tripped circuit ... feeling of frustration!!!! Any ideas on how to fix? What might have gone wrong?

    I have to assume that the motor windings are fried as that is where the smoke and bang came from. Not sure what would cause that as it was running without the capacitor. Maybe some weakness was caused earlier and just couldnt handle the power.

    Does anyone have a spare motor? Is it worth getting it rewound? ...

    good think that I have a spare grinder

  • #2
    Re: LaSanMarco SM90 Smoke ... Sparks etc

    Originally posted by 73777D767B72417D1E0 link=1245930111/0#0 date=1245930111
    I have to assume that the motor windings are fried as that is where the smoke and bang came from.Not sure what would cause that as it was running without the capacitor.Maybe some weakness was caused earlier and just couldnt handle the power.
    I think you a right as you have alluded above

    Sorry that its happened
    First get it checked to determine it is a blown motor & if it is
    What you should do is cross reference and see if other grinder brands use or share the same motor specifications and get a new one

    Good Luck
    KK

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    • #3
      Re: LaSanMarco SM90 Smoke ... Sparks etc

      Originally posted by 4C484249444D7E42210 link=1245930111/0#0 date=1245930111
      Pulled the capacitor off and tried to run it again and it seemed to run OK, slow to get going and speed up but then good.  So got a new capacitor (450V 10uF) from CoffeeParts.  Replaced the capacitor tonight and was ready to go
      This was a BIG mistake...

      I believe the motor fitted to these grinders is a Capacitor Start Motor with a Centrifugal Switch that switches the Capacitor and the Start Winding out of circuit once the motor gets close to synchronous speed. If the original capacitor has failed Short Circuit, most likely the motor managed to get under way but wont have managed to attain full speed or was very slow to get there.
      This wont have allowed the Centrifugal Switch to disconnect the Start Winding (and the capacitor) soon enough and then the motor has basically run up as a standard Split Phase induction motor for which it wasnt designed to do. When you disconnected the failed Capacitor and then run the grinder (amazing that it rotated at all really), this probably created further weakness in the main winding which became a point of failure once the new capacitor was fitted and the motor run up.

      This is all supposition of course without having the grinder/motor in front of me to inspect and test.

      Should the Motor Winding(s) have burnt out, I really doubt that it will be economical to repair unless you know someone who could do it for mates rates. The hourly rate to rewind small motors aint cheap unfortunately... Scout around in your local area to see if you have any motor rewind shops close by and see if any of them will give you a quote to inspect and repair. You might be able to talk them into doing the job for you for a bag or two of freshly roasted coffee. Always worth trying....

      Mal.

      Link to info on small Single Phase Motors... http://www.clrwtr.com/Single-Phase-E...plications.htm

      Comment


      • #4
        Re: LaSanMarco SM90 Smoke ... Sparks etc

        Interesting article Mal ... and thanks for the info.

        Just had another look at the motor and pulled it apart a bit. The winding look not too bad but the connection to the winding looks very black!

        Also after reading that article and looking at the motor I dont see any switching relay so Im not sure that it is the capacitor start type. Also as the size of the capacitor is very small that would agree. Still will take it to an expert to get their opinion.

        Mike

        Comment


        • #5
          Re: LaSanMarco SM90 Smoke ... Sparks etc

          Originally posted by 24202A212C25162A490 link=1245930111/3#3 date=1245963689
          Also after reading that article and looking at the motor I dont see any switching relay so Im not sure that it is the capacitor start type.
          Its not a relay type device Mike but a mechanically operated switch inside the motor that operates in a very similar fashion to an old Ball-head Governor such as a that found on old Diesel Generators, Steam Engines, etc...
          My SM-90A (now my sons) has a Capacitor Start/Induction Run Motor but that could have changed of course with later models.

          Originally posted by 24202A212C25162A490 link=1245930111/3#3 date=1245963689
          Also as the size of the capacitor is very small that would agree.
          The specs you provided above look pretty typical mate....

          Originally posted by 24202A212C25162A490 link=1245930111/3#3 date=1245963689
          Still will take it to an expert to get their opinion.
          Excellent idea Mike, better to play it safe as there is only so much you can do via the typed word...

          Cheers,
          Mal.

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          • #6
            Re: LaSanMarco SM90 Smoke ... Sparks etc

            Is fixable ... for $650!

            Good thing that i have an IC to keep me going. After a few phone calls Ive been offered a reconditioned SM90 A for $300. Not sure about it at the moment. Thinking about getting a Compak K-3.

            Comment


            • #7
              Re: LaSanMarco SM90 Smoke ... Sparks etc

              Originally posted by 25212B202D24172B480 link=1245930111/5#5 date=1246275251
              Is fixable ... for $650!

              Good thing that i have an IC to keep me going.  After a few phone calls Ive been offered a reconditioned SM90 A for $300.  Not sure about it at the moment.  Thinking about getting a Compak K-3.
              Did they tell you what was wrong Mike?

              Mal.

              Comment


              • #8
                Re: LaSanMarco SM90 Smoke ... Sparks etc

                Yep, the motor was burnt out. Winding were all a funny colour and connections as well

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