Northern Tool chain sharpener running backwards

[John Henry]

I bought one of those often discussed Northern Tool chain grinders for $100, and really liked it, until....

Yesterday, while sharpening my rip chain, the unit slowed down and stopped. I shut it off, and figuring maybe it was hot or something (and I was about to stop anyway) walked away. Well, this morning when I went back and turned it on, the wheel was running very slowly, and then I noticed that it was definitely running in reverse direction than normal. The normal direction (as indicated on the shield as as it ran before) was the wheel toward me at the top, and away at the bottom, as it contacted the chain, thus throwing the grit toward the back. Now it is running in the other direction.

Note that this occurred while the unit was running. I didn't notice that it changed direction, only that it slowed, but could have missed it.

I didn't think electric motors could just do that without a short issue or something. I've read up since then, and learned that there could be a starter capacitor that directs it in the right direction, where the normal running circuit takes over.

Any suggestions what to look for?

 

[tomtrees58]

you got 12 v or 110 tom trees

 

[John Henry]

you got 12 v or 110 tom trees

110V Tom. That's why I thought it was weird, especially switching right in the middle of sharpening (without any heavy load).

 

[JTElectric]

That *could* have a start capacitor, but it's doubtful, it's probably what they call a PSC, permanent split capacitor, basically just another set of windings. When an electric motor "diesels" (Runs opposite the way it's supposed to) it's often times a shorted start winding. You're correct, AC single phase motors cannot reverse direction just by switching the polarity of the wires like a DC motor can.

I'd pop the back cover off, see if there's a cap. in there, could be a small round about the size of a "C" battery, or a small block with 2-4 wires coming out of it. If not, you may have a bad motor, and need a replacement. Good luck, any more questions ask! Justin