Logan 820 wiring issues

Vincent,

I would assume, as others have, that the two black wires go to the run winding. And that the two red wires go to the start circuit, which consists of the start winding, the centrifugal switch, and the start capacitor all connected internally in series. And I also have to assume that you made the resistance readings with the motor completely disconnected from the switch and the line cord. If the latter assumption is true, then the run winding is shorted to the field poles or to the motor frame, something in the start circuit is shorted to either the field poles or the frame, and the start capacitor is leaky (bad).
The reading that you should have gotten with the analog (not digital, which is almost useless for this purpose) multimeter set on any resistance scale is that the needle should have kicked towards zero momentarily the first time that you connected the leads to the red wires and then quickly or slowly gone back to infinity. With a good capacitor in the start circuit, the second time that you connected the meter to the red wires, there should have been little if any needle movement, as the capacitor was already charged up to the internal battery voltage. To take a second reading with a good capacitor, first connect the two red wires together for several seconds.

Anyway, if your readings are valid (meaning that the caveats that I listed above were met), you need both a new motor and a new switch.
 
I may have found the problem. One of the black wires had worn through the insulation where it comes through the motor housing to the connection box. I put heat shrink on it, and the other wires, where they come through the motor housing. I'm going to put rubber grommets where the wires come through the housing and a strain relief where the wires from the switch to the box. I really should have noticed that there was no protection for the wire. Any way, there grounding problem with the black field is gone. I looked at the switch again closely and I think it is fine. The mfd on the capacitor is within the range printed on it. I won't get a chance to put it back together until this weekend and I will also replace all the wiring. I also think the leads from the winding are too long so I think I might shorten them. Thanks again for all the help, really got me looking in the right area.
Can't tell you how much help I've received from this forum on my whole lathe project. Soon be making chips!

IMG_0997.JPG

IMG_0994 (1).JPG
 
Well, perhaps in was a testing error instead. But I will repeat that if you have a steady state relatively low resistance reading through the Start circuit, regardless of what else might be wrong, the capacitor is bad regardless of what its value is.

I assume that after you found and repaired the shorted black wire, that measuring the resistance to ground of the black circuit now shows a reading of at least sever megohms. What about the red circuit? Your notes said that it also had a short to ground.
 
Sounds like you found the problem- your switch connects like this inside:
drumDiag1LG.jpeg
And the diagram in your first post is correct
Mark
 
It works! The problem was the wire rubbing against the case. I wrote the wrong numbers for the red wires, it wasn’t 0.0ohms, it was 0.L. Old age and bad eyesight. I installed rubber grommets where the wires come through the motor housing and replaced the power cord and used flexible conduit from the switch to the motor. I found the wiring diagram on industrial-electronics. com for the switch. Runs great and everything’s works! Thanks for all the help. I’d still be thinking I needed a new circuit installed in the basement.

10287E79-08B7-46AE-98C5-F62458113513.jpeg

6D4F0BC7-F22E-4828-B57B-B5A36521F1DE.jpeg

D45D456D-A7D2-4843-9447-C117763184C5.jpeg
 
Back
Top