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Help me reverse this motor please.

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Forum topic by JustJoe posted 11-30-2013 11:17 PM 1499 views 0 times favorited 19 replies Add to Favorites Watch
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JustJoe

1554 posts in 1500 days


11-30-2013 11:17 PM

I’m not scared of electricity or motors but this one has me stumped. I need to reverse the direction it’s running and there is no diagram on/in it. It’s a JET 3/4 HP, 110/220 1725 rpm 4-pole motor. I opened it up inside expecting to see more wires than this:

I’ve got a black and red coming out to one lead.
I’ve got a yellow and white coming out to the other.
And I’ve got a smaller black and red going from the motor to the start/run capacitor.

Switching the two incoming leads doesn’t reverse direction of course. I knew that, but tried anyway – hoping the laws of electricity had changed since I last played with it.

I think I can switch the two wires on the capacitor, just reverse the connectors they’re on. But a little voice in the back of my head is saying I’m supposed to do something before playing with capacitors. Is that right? Or should I try switching something else?

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19 replies so far

View Greg In Maryland's profile

Greg In Maryland

550 posts in 2460 days


#1 posted 11-30-2013 11:24 PM

Does that little voice tell you anything else?

Greg

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JustJoe

1554 posts in 1500 days


#2 posted 11-30-2013 11:27 PM

Nope, it just keeps whispering to me to be careful with the wiring.
Oh, and redrum. It says redrum a lot but I don’t speak spanish so I don’t know what he’s saying there…

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mahdee

3551 posts in 1230 days


#3 posted 11-30-2013 11:30 PM

I once had a pretty strong magnet that touched the side of my table saw and the darn thing would spin in the wrong direction. Being ignorant as to how to reverse the reverse, Ended up buying a $600 table saw that has made me wish keeping the old Craftsman I had paid $240 for.

-- earthartandfoods.com

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johnstoneb

2143 posts in 1635 days


#4 posted 11-30-2013 11:37 PM

You need make sure the capacitor is discharged before messing with it. Short across the contacts with a screwdriver or something similar. I don’t think reversing leads on the capacitor will cause it to change direction.

-- Bruce, Boise, ID

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JustJoe

1554 posts in 1500 days


#5 posted 11-30-2013 11:43 PM

Thanks Bruce – I switched the leads without hurting myself and you’re right, it didn’t change direction.
So I’m back to those two pairs of wires.

I’ve got black/red out and white/yellow out. Time to start playing around.

I’ll try black/white and red/yellow
then black/yellow red/white.

If all of AZ south of Tucson goes dark tonight, blame it on me… :)

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cutworm

1075 posts in 2255 days


#6 posted 12-01-2013 12:45 AM

I don’t think it’s reversible. Hope I’m wrong.

-- Steve - "Never Give Up"

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JustJoe

1554 posts in 1500 days


#7 posted 12-01-2013 12:51 AM

I’m beginning to doubt it myself. I tried both of the alternate wiring pairs. One made it do nothing, the other made it hum a bit, no movement, and a big spark when I pulled out the plug. I’m trying to remember where I got it and I think it was an old Jet bandsaw. I’ll have to dig in the shed tomorrow and find another motor.

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mpsprunger

16 posts in 1323 days


#8 posted 12-01-2013 01:24 AM

No all motors are reversible

View Greg In Maryland's profile

Greg In Maryland

550 posts in 2460 days


#9 posted 12-01-2013 01:28 AM

Well Joe, your little Spanish voice has taste: RedRum

Greg

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REO

889 posts in 1536 days


#10 posted 12-01-2013 01:40 AM

All motors are reversible. some just require a little more work to get it done. I’ll poke around a little and see what I can find for you. you will most likely have to take the end bell off the motor and dig out some of the tags. split them and re attach them properly. this will give you an idea of what you may be in for.
https://www.google.com/url?q=http://lumberjocks.com/topics/48372&sa=U&ei=PZOaUsq9MKGqyAHFuoDwAw&ved=0CAYQFjAA&client=internal-uds-cse&usg=AFQjCNHMXS5ybsa-LBWGHQnD05FG1yurNQ

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JustJoe

1554 posts in 1500 days


#11 posted 12-01-2013 01:42 AM

No need to do do the research. I’ve got enough used motors piled in the shed that I should be able to find one that’s either already going the right direction, or one that is clearly labeled as to how to reverse it.
Thanks though.
Joe

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View ernie's profile

ernie

14 posts in 1469 days


#12 posted 12-01-2013 01:43 AM

Joe
Try this one. Good for 110 or 220V sigle phase motors. Look down to page three, excellent schematics.

http://igor.chudov.com/manuals/ElectricMotors.pdf

ernie

-- Ernie, Etna, WA

View TopamaxSurvivor's profile

TopamaxSurvivor

17664 posts in 3138 days


#13 posted 12-01-2013 04:27 AM

Look on the name plate. It will say if it is reversible. Generally speaking, a reversible single phase motor will have about 6 leads. Swapping # 6 and # 8 will reverse it if it is reversible. Looks like you have 4 leads. Reversing the cap leads will do nothing; it will still do what it did before the leads were swapped ;-)

Edit: I should have said 5 and 8

-- 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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jonah

687 posts in 2761 days


#14 posted 12-01-2013 12:08 PM

Just in case there are people reading this thread that think doing what Joe did is a good idea, it is not a good idea to try randomly pairing wires on a motor and then powering it up. You will short the motor that way, and will more than likely completely ruin it, start a small fire inside it, or both.

I’m betting that motor is now dead.

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JustJoe

1554 posts in 1500 days


#15 posted 12-01-2013 12:40 PM

And you would lose that bet. It still runs quite nicely.

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