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!

I'm going to let Al or Waste comment on that one. I'd be guessing.

Ben

I alerted Al to pop over here and take a look and see if he can help you.

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

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

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

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

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

Quote:

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Originally Posted by CarlD

Al's very resourceful. Always has been.
Carl

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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.

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

Resourceful Al:

https://lh3.googleusercontent.com/_b...s/s800/511.jpg

Great. You found it. Thx, Ben!

That Al. What a goof-ball. Wonder how long it will take him to discover this. And, when he does find it, he can tell you what all of it is for. I *think* the smaller bucket filled with rocks goes inside the orange bucket which is then sunk inside a hole he chips in the ice so he can go ice fishing!:D

Talk about hijacking a thread.....haha.
Back on the topic....Carl is right in that the method just tells you of it is shorted, open, or behaving like a cap should. It's actually visually easier with an analog meter, you know the ones with an actual needle as opposed to a digital readout but both work the same way. An ohm meter works by applying a small voltage to the device and measuring the current flow, then calculating resistance.
Keep us posted on your progress.
Al

Thanks to all for the assistance. Was able to pull and test the capacitor with a multimeter. Didn't measure capacitance so had to use resistance. Discharged the cap, set the meter to 1k ohms and touched the leads. The needle at rest was on the infinity side of the scale, after touching to the cap it quickly pegged towards 0 then returned immediately to infinity. No slow return as i've seen in other guidance on testing caps. Does this indicate failure? Was able to disassemble the rear of the motor and observe the following components which i'm not sure if/how they would affect the low speed

terminal plate where the power comes in - a little dirty but no signs of damage
some sort of micro switch with a flat metal lead that protrudes towards the motor shaft - tested with the meter for continuity and moved the switch, seems to be ok. What exactly is this switch?
about a 1" dia klixon thermal protector (I believe) Could this have been damaged and cause low speed to hum? Can it be checked? Anyone know where to find one if I need it?

Also, as I removed the end cap a plastic collar came out in two pieces which I believe was some sort of collar that was attached to a rotating switch on the motor shaft. What does this control? Could it's failure have affected the switch or is it just some sort of dirt/debris collar?


Lastly, some info on the motor which might be helpful

Century Magnetek 230V
2 speed 1.5/.25 HP
Type CXPM
Frame 56Y
Serial BR4-223
Part 177144
Encl DP

ALso have a pic of the end cap which would probably be helpful but didn't know how to attach.

Thanks again

Thanks Al. Wasn't sure if I replied correctly so resending this to you. Sorry if you got it already. Was able to pull and test the capacitor with a multimeter. Didn't measure capacitance so had to use resistance. Discharged the cap, set the meter to 1k ohms and touched the leads. The needle at rest was on the infinity side of the scale, after touching to the cap it quickly pegged towards 0 then returned immediately to infinity. No slow return as i've seen in other guidance on testing caps. Does this indicate failure?

Was able to disassemble the rear of the motor and observe the following components which i'm not sure if/how they would affect the low speed

terminal plate where the power comes in - a little dirty but no signs of damage

some sort of micro switch with a flat metal lead that protrudes towards the motor shaft - tested with the meter for continuity and moved the switch, seems to be ok. What exactly is this switch?

about a 1" dia klixon thermal protector (I believe) Could this have been damaged and cause low speed to hum? Can it be checked? Anyone know where to find one if I need it?

Also, as I removed the end cap a plastic collar came out in two pieces which I believe was some sort of collar that was attached to a rotating (centrifugal) switch on the motor shaft. What does this control? Could the broken collar have affected the switch or is it just some sort of dirt/debris collar?


Lastly, some info on the motor which might be helpful

Century Magnetek 230V
2 speed 1.5/.25 HP
Type CXPM
Frame 56Y
Serial BR4-223
Part 177144
Encl DP

ALso have a pic of the end cap which would probably be helpful but didn't know how to attach to reply.

Thanks again

send pics to poolforum.pics AT gmail DOT com, and we'll post them.

-ben

I would think the cap is OK. Caps either short or open and you're indicating some capacitance. If you use a higher range on the VOM the test current will be lower and you'll see a slower response.
As for the microswitch and the parts that fell out. My guess is the switch is the starter switch and the thinggy that drives it broke.
The Klixon is an overtemp switch. Normally closed and opens at high temps. They usually have a temperature stamped on them but maybe not. Should read zero ohms when disconnected. If you don't disconnect it you may be reading resistance of a winding instead. Never had to buy one but Klixon has been around for years and should be a common item if you look in the right place like McMaster or some place like that. I doubt it's bad.
The centrifugal switch is closed until the motor is up to speed, then opens. It connects a separate winding with the capacitor in series. (usually) The starter circuit gets the rotor turning in the right direction. I'm thinking that if you measure the resistance of the microswitch it will be open. The centrifugal assembly usually makes physical contact with the switch until up to speed then pulls away so there is no friction and wear of the mechanical components when running. This could definitely be your problem.
On the two speed motors they switch another set of windings in to halve the rotor speed and I'm not sure how all this plays together. Never played with a multi-speed motor. In any case you have to figure out the jizsaw puzzle of broken parts.
Al

Al, got a new toggle switch, wired it up and put the motor back together. The motor will start on high speed but will not start in low speed, just hums. However, When the motor is running on high and I flip the switch to low it continues to run on low with no problem. There is only one capacitor mounted on top of the exterior of the motor housing. The centrifugal switch seemed to move freely and I cleaned the contacts off with some emery cloth. Any ideas? Thanks again

Definitely something in the starter circuit for the low speed. On any of these type motors, when you lose the starter, you can get it going in either direction by spinning it manually. That's what's happening when you flip from hi to lo. To be honest I'm not sure how the starter circuits are configured for two speed motors. Never had to look into it. I'll see what I can dig up.
Al