Troubleshooting an Enco lathe motor

[markba633csi]

This is carrying over from Harry's conversation. We had just determined his control box is ok and the motor has a fault.
-Mark

 

[Harry Knutz]

Thanks Mark,

The motor is disconnected and on the bench.

 

[markba633csi]

Let's see how your meter behaves when measuring a cap. It will be helpful later. Short the cap first with a screwdriver and then measure it with your meter on ohms.
You should see the reading start off low and start rising. When it seems to stabilize after a few seconds, reverse the test leads. Same thing should happen. Swap them again. Same thing. When you are getting a repeatable result, put the cap aside and connect the two wires that went to the cap together and measure ohms between the jumper straps and the z terminal that had the red wire. You should see a low ohm value.
Edit: short the cap terminals with a piece of wire if that's easier

 

[Harry Knutz]

Let's see how your meter behaves when measuring a cap. It will be helpful later. Short the cap first with a screwdriver and then measure it with your meter on ohms.
You should see the reading start off low and start rising. When it seems to stabilize after a few seconds, reverse the test leads. Same thing should happen. Swap them again. Same thing. When you are getting a repeatable result, then wire the cap back on the motor. Now, do the same test only between the jumper straps and the Z1 terminal that had the red wire. Should get the same thing as measuring the cap as before. This tests the start leg.

The cap is actually riveted on, I will have to cut the wires, I will take a pic.

 

[markba633csi]

Edit: Check post 3 I just changed it
Don't cut the wires just put a jumper wire across the cap terminals if you can

 

[Harry Knutz]

Ok I clipped a jumper wire onto the 2 terminals on the cap and then placed one probe from my meter on the terminal that had the red wire on it and put the other probe to the ground screw. 0 ohms were measured.

Ok I put the probes on the cap and the ohms went up to 8 or 10 and then dropped but not all the way down.

 

[markba633csi]

Ground screw? The jumper straps on the motor terminal block that are in a "L" configuration- that should connect to one meter lead. The other one to the terminal where the red wire was connected. You should get some low ohm reading like 5 to 10 ohms or so with the cap jumpered

 

[Harry Knutz]

Ground screw? The jumper straps on the motor terminal block that are in a "L" configuration- that should connect to one meter lead. The other one to the terminal where the red wire was connected. You should get some low ohm reading like 5 to 10 ohms or so with the cap jumpered

I will come back out here after dinner, Like I said, I have no clue what I am doing so I know it sounds easy for you, But I need it spelled out pretty much.

 

[markba633csi]

No problem, and feel free to stop when you are tired or it's late. That's when mistakes happen.
I think you might have found a problem in post #6- we'll have to look at that again. None of the motor terminals should show any path to the case ground

 

[Harry Knutz]

Ok, With the cap still jumpered, I touch one probe on the L-Strap and the other to where the red wire goes, Zero ohms, Nothing happens.


Edit: When I checked the cap, The wires were still connected, I have not cut them. But the jumper is removed, Do I need the jumper on while testing? When I do the first test It goes up to 8 or 10 and then comes down to around 3, Then I switch the probes and it goes up to around 19 and drops some.