The Electric Motor Blues

Thread Starter

supo

Joined Feb 28, 2007
6
I am seriously in over my head here, so please bear with me. I need some help!!

I boought an electric motor from someone on ebay. Here is a link to the auction if you would like to see it:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=008&sspagename=STRK%3AMEWN%3AIT&viewitem=&item=180084249296&rd=1&rd=1

If you looked at the link you'd have found that this is a 1/2 hp 5 speed motor, I applied white wire from an AC outlet in my basement to the white wire on the motor (marked common) and the black wire from the outlet to the black wire on this motor which is labeled as the wire for the fastest of the 5 speeds.

Upon application of the power, the motor doesn't turn, just hums, so I immediately break the connection and tried the yellow wire instead of the black (lower speed instead of the higher speed) again just a hum and no motion.

Am I not hooking this up properly? Do I need some other electronic doo-hickeys to start this motor? I also bout a 3 speed switch, but I won't get into that untill I find out if this motor even works.

Thank you in advance for any help somebody may be able to offer.
 

Thread Starter

supo

Joined Feb 28, 2007
6
The voltage is listed as 115, I assume that it is AC, but do not know for sure.

Yes, the capacitor is hooked as shown (if that is the grey metal box on the purple wire)

I emailed the guy and asked him how he tested it. I haven't heard back from him yet.
 

Ron H

Joined Apr 14, 2005
7,014
The voltage is listed as 115, I assume that it is AC, but do not know for sure.

Yes, the capacitor is hooked as shown (if that is the grey metal box on the purple wire)

I emailed the guy and asked him how he tested it. I haven't heard back from him yet.
I think a bad capacitor will cause these symptoms.
 

Thread Starter

supo

Joined Feb 28, 2007
6
Thank you for the input.

I read what the capacitor is for and still wonder whether or not I actually need it. I do not know if this is a run capacitor or a start capacitor, but if I remove the capacitor should I attach the 2 purple wires to each other, should my motor run when I apply the power if I did this, or is likely to not be able to start even with no load?

Also does anyone know what the specs should be on the capacitor? Could I just have the wrong one here? This is what the capacitor says on it:

York 000815
7MFD 370VAC
81A3901 60Hz
SFA377A21GOP3
 

thingmaker3

Joined May 16, 2005
5,084
Do not attach the capacitor leads together! I was unable to find any data on your particular motor either at Emerson's website or through Google, but shorted capacitors are never useful.
 

Ron H

Joined Apr 14, 2005
7,014
Capacitors are not added to motors without good reason. If the capacitor is defective, or missing, the motor will not run. The cap is a 7.5 microfarad, 370 volt run capacitor. You can get a new one on Ebay for $8.05 including shipping.
Keep in mind that this may not be the problem. It may be a wiring problem, or a motor problem.
 

Thread Starter

supo

Joined Feb 28, 2007
6
So here is an update on my struggles:

First of all thank you to those of you who have tried to help.

I was thinking that the shaft should spin freely when not powered on, so I thought that since it is not spinning freely, that it is just physically stuck, since this is a used motor, maybe the bearings are shot and the motor just hasn't got the torque to get started, so I hooked a 2 inch pulley to the shaft and tried to turn the shaft by hand after plugging the cord in and the motor ran, so I let it run for about 30 seconds and unplugged it, then tried it a few more times and it ran. So should I still replace the capacitor? Could that be a reason for the poor starting performance? Should I attempt to replace or repack the bearings? Or just toss the motor and try again with a brand new one?

Thanks again for the help.
 

beenthere

Joined Apr 20, 2004
15,819
I've seen old motors that got sticky when the lube aged. Are there oiler holes or channels to the bearings? If that's the case, flood them with oil (20 weight) and try spraying WD-40 on the shaft near both bearings. Let things stand for a couple of hours for the oil to penetrate, and see how it goes.

On the other hand, if the motor runs in ball bearings, you'll probably need to replace them. There's no way to relube dry ball bearings.

Another question is: does the motor run quietly, or does the shaft rattle in the bearings? If that's the case, then the bearings are shot. You can replace them, but you'll also need to inspect the shaft surfaces for scoring. The shaft has to be smooth or it will just wreck new bearings.
 

Ron H

Joined Apr 14, 2005
7,014
I've seen old motors that got sticky when the lube aged. Are there oiler holes or channels to the bearings? If that's the case, flood them with oil (20 weight) and try spraying WD-40 on the shaft near both bearings. Let things stand for a couple of hours for the oil to penetrate, and see how it goes.

On the other hand, if the motor runs in ball bearings, you'll probably need to replace them. There's no way to relube dry ball bearings.

Another question is: does the motor run quietly, or does the shaft rattle in the bearings? If that's the case, then the bearings are shot. You can replace them, but you'll also need to inspect the shaft surfaces for scoring. The shaft has to be smooth or it will just wreck new bearings.
This would be a bigger problem with motors with low starting torque, which I think is the case with a blower motor such as this one. I have had similar problems with oscillating fan motors. I think beenthere's suggestions are good ones.
 
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