Capacitor Replacement for Table Saw Motor

Discussion in 'Technical Repair' started by Toutatis, Jul 10, 2018.

  1. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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    Hi

    I have acquired a table saw with a damaged motor. I think I have narrowed the faulty part down to a capacitor (using the scorch marks!) however the motor is 15 years old so finding a replacement for what I think is a bespoke capacitor doesn’t appear to be simple. I have included a pic of the part.

    Does anyone have any idea where I could get a replacement or what to replace it with as an alternative?

    Would appreciate any advice you can offer but realise I may be running out of options!

    Thanks

    Matt 79E417F8-FF99-4C20-BE65-440AA896F4DC.jpeg
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It looks like a 1μf just ensure you obtain a motor start rated version, most motor rewinders should have them.
    Stay away from the Asian Versions.'
    What are the symptoms?
    Max.
     
  3. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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    Thanks Max. I only ran the tool very briefly as I had already been told that it was smoking, but when I ran it there was a blue flame that shot out of the back.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Doesn't sound good!
    Sounds more like a burn out.
    If it is just the cap, often you can spin the shaft and turn on the power at the same time, if it runs it is the cap.
    Max.
     
  5. AlbertHall

    AAC Fanatic!

    Jun 4, 2014
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    Kjeldgaard likes this.
  6. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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    Hi, and thanks. Yes, three wires but oddly I think there were three out of both ends, will double check tomorrow.
     
  7. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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    Hi, it has 3 wires coming out of one end and two out of the other.
     
  8. ebp

    Well-Known Member

    Feb 8, 2018
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    I agree with Albert that it is three capacitors in one and used for RFI suppression, so the motor will probably work just fine with it removed completely. It is a bit of an odd thing to find on a conventional induction motor, since the only thing it could suppress would be electrical noise from a centrifugal starter. Motors with brushes are used on some portable direct-drive table saws, and they will generate a lot of RFI.

    Some photos of the whole motor would be helpful.

    I think the first line is zero comma one mu F
    0,1µF
    same as 0.1µF
    It looks like the line at the bottom is 1,6 MHz

    [EDIT] It may be hard to find an all-in-one replacement but getting suitable capacitors separately will be no problem. 2500 pF for the "Y" caps is a bit of an odd value, but available. 2200 pF or 2700 pF probably would be just as good and allow more choice. 0.1 µF is extremely common as an "X" cap. You would want a small enclosure to house the caps.
     
    Last edited: Jul 11, 2018
  9. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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  10. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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    Thanks for the advice, unfortunately can’t get a picture of the motor because it is buried in plastic!

    I have included a ‘circuit diagram’. Not sure if this helps but I think could manage to bypass the capacitor altogether if it wasn’t for the third wire coming in at the bottom of the capacitor. Any ideas what I would do with this if I bypasses the capacitor?

    Thanks
     
  11. ebp

    Well-Known Member

    Feb 8, 2018
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    Three wires to the motor does suggest the cap might have something to do with motor starting or running, but the values marked seem far to low for that. Is there a chance on of the wires to the motor connects to the motor housing?

    Is the line cord really just two conductors - no ground?

    Is this a direct-drive saw (motor shaft is blade arbor)?
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What is the name of the table saw?
    All the links that come up for the cap indicates a east European origin, Polish etc.
    Max.
     
    Last edited: Jul 21, 2018 at 4:26 PM
  13. Toutatis

    Thread Starter New Member

    Jul 10, 2018
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    Hi

    Make of table saw is Smalcalda, and motor is VEB mikromat dresden. I was told it was German and the name seems to fit.

    Motor does directly power the blade.

    On looking at it in lore detail it looks like the two wires out of the ‘top’ of the capacitor go into and back out of the motor.

    The third cable at the bottom of the capacitor goes towards the motor but doesn’t seem to be part of the circuit for the two cables coming out of the top of he capacitor. Could this be an earth connected to motor housing? If it’s relevant this cable seems to slide backwards and forwards to this connection although I can’t see it to investigate further.

    Thanks for the continued advice, it’s greatly appreciated, would like to give this table saw a new lease of life!

    Matt
     
  14. MaxHeadRoom

    Expert

    Jul 18, 2013
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    It could well go to the frame of the motor as part of a R/C suppression network, which could also indicate it might be a brushed (Universal) motor.
    Do you know the rated RPM of the motor?
    Max.
     
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