Diagnosing, and repairing 15 amp universal motor...

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Forum topic by dbhost posted 10-07-2009 03:52 PM 2256 views 0 times favorited 3 replies Add to Favorites Watch
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5767 posts in 3472 days

10-07-2009 03:52 PM

Topic tags/keywords: question

Here’s the scoop. I bought a Ryobi BT3000 missing the stand, and it won’t start up, for $10.00. I already have a BT3100, and had purchased the 3000 to refurb for donation to a community remodeling project (most likely my churches Habitat outreach ministry).

It would appear my brain is REALLY rusty when it comes to tracking down problems in universal electric motors.

Can anyone point me to a good HOWTO, or book on trouble shooting electric motors?

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3 replies so far

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18425 posts in 3916 days

#1 posted 10-07-2009 10:03 PM

You might have bearing play end to end , but not sideways. If you do the bearing is bad. Check contunity of the motor leads to ground with a ohm meter. It should be at least 15 mega ohms. A high voltage ohm meter is best for this test, but it costs more than the motor is worth. You should have contunity through the leads. Universal motors are the cheapest motors possible to make. Generally not worth repairing. Take it to Grainger or some other industrial supply and get a new one that fits the mounting, shaft and voltage. .

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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5767 posts in 3472 days

#2 posted 10-07-2009 10:25 PM

Cord is definately good, not sure how to check the switch, brushes are reasonable… Some wear, not losing connection though.

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1507 posts in 3704 days

#3 posted 10-07-2009 11:09 PM

it’s not the same animal, but i recently had the motor on my coffee grinder konk out on me. i thought it was the switch at first, but after a brief inspection with a multimeter, found there was a break in the line somewhere between the winding and brush contact – under the insulation (!). i couldnt replace the wire without damaging the windings, but simply shunting it to the brush contact was a quick fix.

anyway, the lesson is: do please look at those sorts of easy fixes first.

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