Reversible motor runs fine one way, blow circuit breaker in reverse.

[silence dogood]

Do you have the 9" Lathemaster? Mine is the 8x14. The on/off switch, the drum, and the wiring is different from mine. Even the wires are white not black although there are other colors. I would recommend not to do the reverse wire short test. The test may tell you what you need to know. The trouble is that there is so much current going through the switches that you may burn the switch contacts. I believe that is why the switch would chatter when you turn the lathe on even after you rectify the main problem. End up replacing both switches because some of the contacts measured over 20 ohms when close. They should measure close to zero. Marba633csi has a good point about the import switches of that type. I replaced mine with a standard drum switch. Modified it so it would fit in the original place. This switch can handle up to a three-horse motor and was much simpler to wire. As for testing the motor. Since you have already opened it up. There should be five wires coming out of the motor. Hopefully, the color code should be the same as mine. Green is ground. U1 and U2 are black and white and are the run winding. V1 and W2/Z2 are the run winding. If you take an ohmmeter to the green and the other lead to any of the four other wires, they should measure open or infinity. If one of the wires measure any kind of short to the green or the metal ground, there is your problem. Most likely, it will be V1 or W2/Z2. You will have to take the motor apart and find the open insulated wire that is causing the short. Good luck, Mark.

 

[Dlb21964]

Do you have the 9" Lathemaster? Mine is the 8x14. The on/off switch, the drum, and the wiring is different from mine. Even the wires are white not black although there are other colors. I would recommend not to do the reverse wire short test. The test may tell you what you need to know. The trouble is that there is so much current going through the switches that you may burn the switch contacts. I believe that is why the switch would chatter when you turn the lathe on even after you rectify the main problem. End up replacing both switches because some of the contacts measured over 20 ohms when close. They should measure close to zero. Marba633csi has a good point about the import switches of that type. I replaced mine with a standard drum switch. Modified it so it would fit in the original place. This switch can handle up to a three-horse motor and was much simpler to wire. As for testing the motor. Since you have already opened it up. There should be five wires coming out of the motor. Hopefully, the color code should be the same as mine. Green is ground. U1 and U2 are black and white and are the run winding. V1 and W2/Z2 are the run winding. If you take an ohmmeter to the green and the other lead to any of the four other wires, they should measure open or infinity. If one of the wires measure any kind of short to the green or the metal ground, there is your problem. Most likely, it will be V1 or W2/Z2. You will have to take the motor apart and find the open insulated wire that is causing the short. Good luck, Mark.

Thanks for this info. My lathe is the 8 x 14, had it since about 2005.

I went ahead and ordered a new F-R switch, simply because it’s cheap and easy to replace. I will take the motor apart when I get some time, probably over the weekend.

 

[markba633csi]

Make careful notes about switch wiring when you go to replace- save many headaches

 

[Dlb21964]

Make careful notes about switch wiring when you go to replace- save many headaches

Oh absolutely. I’ve made that mistake one too many times.

 

[markba633csi]

BTW "caps" is slang for capacitors, those cylinder shaped things with two terminals or wires coming out- they come in all shapes and sizes
and are found in many products besides motors

 

[Dlb21964]

BTW "caps" is slang for capacitors, those cylinder shaped things with two terminals or wires coming out- they come in all shapes and sizes
and are found in many products besides motors

I appreciate your help, and everyone else’s help with chasing down this gremlin. I’ll update the thread when I get the switch and take the motor off.

 

[Dlb21964]

Do you have the 9" Lathemaster? Mine is the 8x14. The on/off switch, the drum, and the wiring is different from mine. Even the wires are white not black although there are other colors. I would recommend not to do the reverse wire short test. The test may tell you what you need to know. The trouble is that there is so much current going through the switches that you may burn the switch contacts. I believe that is why the switch would chatter when you turn the lathe on even after you rectify the main problem. End up replacing both switches because some of the contacts measured over 20 ohms when close. They should measure close to zero. Marba633csi has a good point about the import switches of that type. I replaced mine with a standard drum switch. Modified it so it would fit in the original place. This switch can handle up to a three-horse motor and was much simpler to wire. As for testing the motor. Since you have already opened it up. There should be five wires coming out of the motor. Hopefully, the color code should be the same as mine. Green is ground. U1 and U2 are black and white and are the run winding. V1 and W2/Z2 are the run winding. If you take an ohmmeter to the green and the other lead to any of the four other wires, they should measure open or infinity. If one of the wires measure any kind of short to the green or the metal ground, there is your problem. Most likely, it will be V1 or W2/Z2. You will have to take the motor apart and find the open insulated wire that is causing the short. Good luck, Mark.

 

[silence dogood]

I got my lathe in 2009, so there must had been a change. The on/off switch and drum switch are on separate places instead of one panel like yours. The color code to the motor seems to be the same. Yellow with green stripe is ground. Black and white wires should be run winding. Red and blue should be start winding. The start winding is the one that flips for the reverse. Inside the motor the sorta green wire which was connected to the red or blue (can't remember which) was pinched and caused the short. Hope this helps.

 

[Dlb21964]

I got my lathe in 2009, so there must had been a change. The on/off switch and drum switch are on separate places instead of one panel like yours. The color code to the motor seems to be the same. Yellow with green stripe is ground. Black and white wires should be run winding. Red and blue should be start winding. The start winding is the one that flips for the reverse. Inside the motor the sorta green wire which was connected to the red or blue (can't remember which) was pinched and caused the short. Hope this helps.

So I’m setting my meter on 200 ohms, holding my black probe against the green striped wire, and taking the red probe against each of the remaining 4 wires, correct?

If the wires are good, I should get “I” (infinity) on each wire? Any other reading than that means there’s a short in that wire?

 

[silence dogood]

Yes. You got it. If there is a short, I have a hunch that it will most likely be the red or blue wire. Then you will have to take apart the motor. If you have not done anything like this. First make a mark across the cover and the case. That's so when you put it back together, both pieces will line up. Taking pictures will help a lot. Remove the case screws. Carefully pry apart. The centrifugal switch is the hard part. If you look inside just right, you will see two screws that hold a plastic plate called a centrifugal switch. Inside the wires are a different color. Mine were a blueish green as shown in the previous photo on comment no, 8. This will give you more room to fix the bare spot on the wire. While you are about it, look for any burnt spots and sniff for any burnt smells. Hopefully there won't be any. After repairing the wire, carefully put it back together making sure that no wires get pinched. Spin it by hand to make sure that nothing is interfering with the rotor. Test again to make sure that there are no shorts. After this you should be good to go. Good luck my friend.