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Thread: Two speed pump no low speed

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    Default Two speed pump no low speed

    Have a century magnetek 2 speed pump with an externally mounted capacitor on the top. The speeds are controlled via a toggle switch mounted on the rear faceplate of the motor. When operating the toggle switch, a part of the switch must have broken/rusted off and shorted the wires causing sparking until the power was killed. The switch was removed and pump operation was checked for both speeds by direct wiring. The pump operates fine on high speed but only hums on low speed. Could this be the result of a damaged capacitor? If yes, would it be the top mounted capacitor or are their other internal capacitors or other components that could have been damaged? Thanks!

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    madwil is offline Registered+ Widget Weaver madwil 0
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    Default Re: Two speed pump no low speed

    I'm not Al, but...

    Yes, a humming noise from the motor without movement is frequently a capacitor...
    Whether the motor is internally wired for low speed and externally for high speed, will determine the other part of the question. I think most motors internally are wired for "normal", which is max rated capacity, so the external capacitor is probably the bad one...
    Do you have an electrical meter that reads capacitance (farads, I think)?
    with the right tester, it's easy to check... and many are easy to replace as long as you have a parts source...
    Good Luck!
    Madwil

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    Default Re: Two speed pump no low speed

    I'm a little out of my league here--Al is the better source for this, but Madwil's advice sounds good. Unfortunately, meters people have don't measure capacitance. You usually need a higher end meter for that, like a Fluke 115 or better--and they list at around $160. If you know of a less expensive meter that handles capacitance, that would help.

    Carl
    Carl

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    Default Re: Two speed pump no low speed

    Robb, welcome to the forum. I'm not sure how the 2-speeds are wired or even whether it's a capacitor 'start' or capacitor 'run' configuration. But, the caps are one of the two common failure components. An easy way to test them is with a regular, cheapo, V-O-M- (Volt-Ohm-Milliamp) meter. Less than $20 at Radio Shack. You need to disconnect the cap and discharge it by shorting the terminals together for a little bit. 10 seconds is sufficient. Connect the VOM in the Ohms mode one way and you should see the resistance drop initially then ramp up to some high value. Probably at least a megohm. This is because the VOM puts a small voltage on the leads and the cap is initially discharged and begins to charge.....if it is good. When the resistance stabilizes, reverse the leads and you should see the resistance bang to less than zero and repeat the ramp up to a high value as it charges in the reverse direction. If it is open you will just see a high resistance always. Shorted, zero.
    The other common failure mechanism in a capacitor start motor is cruddy starter centrifugal switch contacts. If there is one it is usually on the back end of the motor and usually easily accessable. If you pull covers you should expose all this stuff including another cap if it's there.
    Hope this helps.
    Al
    16'x32' oval 22K gal IG vinyl pool; ; Hayward S244T sand filter; Hayward superpump 1 HP pump; hrs; K-2006; PF:5.5

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    madwil is offline Registered+ Widget Weaver madwil 0
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    Default Re: Two speed pump no low speed

    never heard of that way to check capacitors before- but makes sense! We all learn a little with each problem posted, hunh?

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    Default Re: Two speed pump no low speed

    Al's very resourceful. Always has been. And it makes a lot of sense. It doesn't measure capacitance, but does show if it's working or has failed--and that's key.

    Carl
    Carl

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    Default Re: Two speed pump no low speed

    Quote Originally Posted by CarlD View Post
    Al's very resourceful. Always has been.
    Carl
    That's the nice version of the description for our dear buddy, Al. Resourceful. You guys would be totally amused at some of the 'resourceful' ways that Al solves problems. But, hey --- you need an idea for how to fix something? He's your man. Might not look too pretty, but it'll work.

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    Default Re: Two speed pump no low speed

    I must admit he hasn't yet caught a fish through the ice-fishing hole in his pool!
    Carl

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