Electric motor hums when I plug it in, before I start the switch, but runs fine when I start it

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Forum topic by SteveHaf posted 12-01-2017 01:52 PM 508 views 0 times favorited 4 replies Add to Favorites Watch
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9 posts in 980 days

12-01-2017 01:52 PM

Topic tags/keywords: scroll saw motor

I have a Delta 40-440 24” Scroll Saw. When I plug it in, the motor hums, before I hit the start switch. When I do hit the start switch, it seems to run fine. Any thoughts on what the cause is and how to troubleshoot and repair?

4 replies so far

View verdesardog's profile


171 posts in 3414 days

#1 posted 12-01-2017 02:20 PM

Could be a bad start switch….

-- .. heyoka ..

View WhyMe's profile


1299 posts in 2364 days

#2 posted 12-01-2017 03:09 PM

I don’t believe the motor should be humming before power is turned on. Has it just started doing this?

View Dustin's profile


707 posts in 1543 days

#3 posted 12-01-2017 03:14 PM

Ground loop?

-- "Ladies, if your husband says he'll get to it, he'll get to it. No need to remind him about it every 6 months."

View SteveHaf's profile


9 posts in 980 days

#4 posted 12-02-2017 04:12 PM

I grounded the green wire in the start switch’s box. If it’s a bad start switch, could I use a simple light switch to test it? If yes, I’m not sure how to wire it – there’s a black, red, white and green wire coming into the box

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