Question about Craftsman 6" Bench Grinder with Lamp
This grinder hums and will not turn when plugged in unless you give it a spin. i dont have a wiring diagram and the wiring had been disconnected for years. the motor has no capacitor and no centrifugal switch but it does have a black rectangual looking item . i think it is a starter relay switch but i have no way of knowing how to test it or to hook it up. the windings coming off the motor consist of two larger wires and two smaller wires.the two larger wires are yellow and red and the two smaller wires are black and white. i have heard of two other grinders having this problem but i have no other like item to compare this grinder with to know how to correctly attach the wires. any help would be appreciated. a wiring diagram would be helpful. thanks Does anyone have a good (cheap) source for the relay?
I know this is an old post, but maybe it will help others looking for information.
I have the Craftsman 1/3-HP grinder models: 397.19580 & 397.19581.
They are Split-Phase single voltage (115 V), and use a Klixon start-up current style relay - 2CR14-224.
The relay is normally open. When the large starting current in the main/run winding circuit is sensed by the the relay coil (term 3 & 4) which is in series with the main winding, the relay contacts close (term 2 & 4).
The one end of the start-up winding is connected to the main coil's BLK wire in the coil pack.
When the relay contacts close the start-up winding is energized. The start-up coil is used to provide a boost to over-come the resting inertia of the rotor.
Once the rotor reaches between 65% - 75% of operating speed, the current through the main winding circuit is reduced to the point that the relay coil cannot over come the return-springs force, acting on the relay contact arm. With the contacts open, the start-up winding is no longer energized.
This should take about 2-3 seconds, if the relay malfunctions, the high current through the start-up windings (thin wires) may be damaged.
Here is a diagram I have made.
Klixon 2CR relays are no longer available.
You may find a suitable replacement here:
Posted on Feb 24, 2016
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Posted on Jan 02, 2017
Hi again, OK, Well since I don't have a wiring diagram and the colors don't help. I am also going to assume it is 110VAC. The larger wires are probably the run or primary, it you remember which ones were connected it will help with polarizing. ( getting it to run in the right direction as well as the start and primary working together). You can use the two terminal switch but you should use a three wire cord. Use the switch to break the neutral and ground the case. The connections should be as follows: Connection 1, would have one of the primaries and one of the starts to neutral. Connection 2, the other start to the relay. Connection 3, the coil side of the relay to the remaining primary. ( if the relay has two connections on one end and one on the other it would be the single) Connection 4, the 3rd position on the relay to hot. That is how a split phase is wired. You may find a simple wiring diagram on the net if you type split phase motor wiring diagram. Good Luck to you, this should Fixya!
Posted on Mar 04, 2009
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