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Thread: Removing Capacitor from Dust Collector Motor

  1. #1

    Removing Capacitor from Dust Collector Motor

    Hi folks,

    This is a Penn State Industries 1.5 HP dust collector DC2V3Y (now discontinued). It has suddenly stopped working.

    The motor runs for about a second then quits. The capacitor looks to be leaking oil - apparently a good sign that it has failed.

    Before removal, I've read that the capacitor should be discharged (to drain any charge it may be holding) by shorting the 2 terminals. The wires come directly out of the capacitor which makes that a bit difficult and I can't seem to be able to pull off the wire nuts.

    I'm really tempted to just cut the wires but thought I'd run it past you guys first.

    Capacitor.jpg

  2. #2
    Join Date
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    Those look like crimp connectors. You'll have to cut the wires. Do make sure to discharge the capacitor first though!!

  3. #3
    Quote Originally Posted by Tom M King View Post
    ... Do make sure to discharge the capacitor first though!!

    Tom,
    Yeah, but that is what I'm asking...how do I discharge it. Thanks for the post.

  4. #4
    Cut both wires at the same time.
    Stan

  5. #5
    Don't worry about discharging it. There is little risk of stored charge on a motor capacitor.

    If you really wanted to, the way to do it would be to cut the wires and touch the exposed ends together.

  6. #6
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    Insulated screwdriver, and look the other way.

    It might have a bleed down resistor anyway, which they do a lot of times-tried to add picture, but it won't show. Picture added in a post below. If it has that resistor between the terminals, chances approach zero that it's holding a charge anyway.



    Last edited by Tom M King; 10-06-2018 at 6:00 PM.

  7. #7
    It won't hold a charge indefinitely. Unplug it for 24 hours and use insulated cutters. And don't stand in puddle of water. Seriously though. as long as you cut one wire at a time and don't get in series with the two wires (cut one at a time) you will be fine. Cut one wire and touch it to a ground and it will bleed off but it probably already has. I've changed out plenty of these and never had an issue. Smart of you to think know about it though.

    Marty

  8. #8
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    Last edited by Tom M King; 10-06-2018 at 5:59 PM.

  9. #9
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    A capacitor charged by AC current typically is not much of an issue. It's the DC-charged ones you have to worry about.
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


  10. #10
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    Quote Originally Posted by Tom M King View Post
    Those look like crimp connectors. You'll have to cut the wires. Do make sure to discharge the capacitor first though!!
    If you are patient you can actually “uncrimp” the wires using lineman’s pliers to reopen the crimps and then pull the wires out, but definitely much quicker to just cut the crimps off.

  11. #11
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    Voltage on a start cap is DC. It could be anywhere from -240v to +240v depending on where its at when removed from the start circuit. You can test its voltage with a meter. Zero issue cutting the leads as long as you dont ground the terminal when doing so. Once done put a 5 watt 5000 ohm (or larger ohm lower watt) resistor between the two leads and you can then use a meter and see when it is zero volts. Caps dont just loose their charge by sitting overnight, it takes a load to discharge a cap. To test your cap with your meter, set it to dc volts and touch each lead to each terminal/wire.
    Last edited by Mike Heidrick; 10-07-2018 at 11:51 AM.
    Glad its my shop I am responsible for - I only have to make me happy.

  12. #12
    Many thanks to all the folks that answered my post.

    The good news is that I'm still in the land of the living after cutting the wires.

    Sad news is, after installing a new capacitor, of same uF and V, it still doesn't want to start up.

    Maybe 1.5 sec and then it dies.

    I put a board up against the air intake - no difference.

    I'll try different electrical outlets later today (but that didn't work for the original capacitor so I'm not too hopeful)

    A label on the dust collector motor says it is 11 amps and I'm pretty sure the trip beaker in the house electrical panel is 15 amp.

    Suggestions welcome, as I'm running out of ideas.

  13. #13
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    Is the replacement capacitor an AC capacitor made specifically for motors? If the terminals are marked with "+" and "-" it's a DC electrolytic capacitor instead and won't work even if the capacitance and voltage ratings are the same. Note that if you can't find an identical replacement capacitor one with higher ratings should work.

    For the motors I've had with start capacitors, the motor will just hum with a bad or missing capacitor but will run if nudged by hand. I've operated lathes and a bandsaw this way for a while until I got replacement capacitors. They would run in either direction depending on the direction of the push. But running in the correct direction for 1.5 seconds doesn't fit my own experience of motor capacitor issues. For a hint, perhaps you can monitor the voltage and the current the motor is pulling during this time. If stumped and can take the motor out easily, a local motor repair shop can check it out.

    JKJ

  14. #14
    Starting for 1.5 seconds then shutting off is "failed centrifugal switch" symptoms. See if you can find the centrifugal switch and try to blow it out and/or clean it.

  15. #15
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    For the record its bad advice to just short the terminals together on a cap - you should always use a resistor to limit the current.

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