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- Dec 25, 2011
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Most capacitor start motors made since about 1950 (and many made earlier) have the start capacitor mounted under a cover on the outside of the motor body. The start capacitor in this case is usually cylindrical, And you can tell at a glance that the motor is a Capacitor Start type. Some motors made earlier (and a few made since) have a rectangular start capacitor hidden in the base casting. These you have to look more closely to ID. However, if the nameplate on the motor says "Split Phase" as I assume from your most recent post it does, then there is no start capacitor.
That being the case, and given that the motor worked for a while and suddenly quit starting on its own but does run if you start it manually, the most likely culprit is that the centrifugal switch (which opens to disconnect the start winding after the motor starts and gets up above about half speed) is stuck in the open position or much less likely, the switch contacts are burned. Less likely is that one of the connections to the start winding was loose or corroded and suddenly went open. However, I would probably unplug the line cord and wiggle any spade connectors, loosen and then tighten any electrical contact screws, and tighten any wire nuts first. And then try the motor.
If that doesn't fix it, then you should unplug the motor, remove it from the lathe, and carefully remove the bearing carrier casting from the field housing on eht end of the motor containing the wiring and check the centrifugal switch. As there are many types, I can't describe exactly what it will look like But the rotating part will be mounted on the armature shaft and the switch itself on the bearing carrier casting. Be aware that jiggling things while removing the casting may unstick the centrifugal weights. Lubricate the obvious points with a very little oil and if possible manually cycle the weights and the switch and then put it back together and try it.
That being the case, and given that the motor worked for a while and suddenly quit starting on its own but does run if you start it manually, the most likely culprit is that the centrifugal switch (which opens to disconnect the start winding after the motor starts and gets up above about half speed) is stuck in the open position or much less likely, the switch contacts are burned. Less likely is that one of the connections to the start winding was loose or corroded and suddenly went open. However, I would probably unplug the line cord and wiggle any spade connectors, loosen and then tighten any electrical contact screws, and tighten any wire nuts first. And then try the motor.
If that doesn't fix it, then you should unplug the motor, remove it from the lathe, and carefully remove the bearing carrier casting from the field housing on eht end of the motor containing the wiring and check the centrifugal switch. As there are many types, I can't describe exactly what it will look like But the rotating part will be mounted on the armature shaft and the switch itself on the bearing carrier casting. Be aware that jiggling things while removing the casting may unstick the centrifugal weights. Lubricate the obvious points with a very little oil and if possible manually cycle the weights and the switch and then put it back together and try it.
