Dc Motor Hum.....

calstar

calstar

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Just installed this motor on my 1987 12x36 jet using a Minarik controller, drive belts not on so its not running under load. With power the motor runs smooth but hums quite loudly(gotta be louder than usual, never run a DC motor before) and smells a little hot(not to touch and no magic smoke escaping). Ive had the motor a couple of years but only ran it when testing the mill it came on, I don't remember it making any noise then but it was a while back, memory banks lacking on this one. Checked the brushes they're in good shape, not much wear, thats about all I know what to look at. If anyone can help me try to figure it out I'd really appreciate it.

thanks, Brian

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do you have the field wires and armature wires hooked up..4 total
 
btw they do hum...mainly because it is not true dc like from a battery
 
Toolmaster, yes both the field and armature wires are connected to the controller. I don't know if its more of a hum than buzz but the noise is constant regardless of the motor rpm as controlled by the controller. I did a google search before posting this and found quite a lot about DC motor hum/buzz but sorta hard to wade through it all with my level of knowledge. I'm going to double check the controller connections as per instructions and see if I did something wrong.

Thanks, Brian
 
The hum should not be loud and the motor should not get hot with no load.
 
Yep, all connected as per instruction/wiring diagram. Here is something I just heard, without touching/moving the speed pot dial the rpm appears to be pulsing, not continuous but every 5 seconds or so. I have the pot mounted in a junction box and when mounting it I dropped the box twice; maybe the pot got screwed up and is not sending a clean signal(if that makes sense)? There's a Radio Shack a mile from me, I think I'll get a new pot and see if thats it(when in doubt switch parts, right?;)). The hum is the same when I switch motor rotation by changing the armature leads on the controller.

The noise is loud enough to hear it across my garage/shop but its the smell that concerns me; although there is not visible smoke I have a slight headache from sticking my head close to the motor (not doing that anymore!!) so something is wrong.

Brian
 
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i'd suspect a controller fault, there should be no loud humm
 
could be the settings inside the control box...if not set right the motor will pulse
 
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