Mark V shaft turns by hand but cleaned motor won't run

[Culprit]

Here is my guess: your inertia switch stuck closed and was not disconnecting power from the start windings after the motor was running and up to speed, and now your start windings are bad (burned up, something melted and shorted the winding, etc).

If you still have the motor apart as your picture showed, test continuity of the windings. I've only taken apart my 1955 3/4 HP motor, so I will assume yours is the same as mine. There should be one start winding and two run windings. Look at the motor carefully and trace the wires comparing them to a schematic of the motor - see sloppy hand-drawn one here.
Once you map what you see in your motor to the schematic, you will know where to stick the probes to check the continuity of the start windings. On my motor, the insulation covering the wires leading to the start and run windings were different colors, so that made it easier to figure out what was what. My run winding leads were sheathed in black, and my start winding leads were sheathed in white. Your motor is much newer than mine, and made by a different company so the convention might not be the same, but there might be a convention there if you look for it.


This guess of mine assumes the capacitor is good. But for $6 I would replace it anyway.

[billmayo]

Check ohm readings at the capacitor and power leads, no AC power applied. Always open to ground, 1-2 ohms for run windings, 3-5 ohms for start windings. Check that the the switch point are closed which reads as a short across the points. Normally if any bad/shorted windings, you will see the coil winding straps/wraps are burnt off at some place and you can smell the burnt winding (stinks). Use the highest ohm reading to check the capacitor. Will show a short and very quickly go to an open reading. Be sure to discharge the capacitor before handling.

[robfish]

Thanks everyone for your help and suggestions - I really appreciate it.

I think, though, that it is time for me to take the electric motor to a local shop and get an estimate on having it repaired.

Thanks again!

Rob

[JPG]

Thanks everyone for your help and suggestions - I really appreciate it.

I think, though, that it is time for me to take the electric motor to a local shop and get an estimate on having it repaired.

Thanks again!

Rob

Remove the two screws that are holding the terminal board etc to the motor. That will allow you to 'see' more of the actual switch contacts which are probably under the rubber boot.

From your description(s) there is no doubt in my mind: 1)the start switch contacts are NOT closing reliably, 2) the capacitor is still good, 3)both the run and start windings are NOT burned(pix).

[robfish]

That will allow you to 'see' more of the actual switch contacts which are probably under the rubber boot.

YaHooOOOOoooOOOoooOOOoooo!!!!!

I decided that before buttoning up the electric motor and taking it to a repair shop, I'd follow your suggestion and look at whatever was under the rubber boot.

When I removed the switch assembly and slid the boot out of the way, I saw a set of contacts that evidently open and close as the "yoke" moves in and out. I didn't see anything that looked unusual, but when I blew compressed air into the switch assembly a surprising amount of sawdust flew out.

As you've probably guessed, when I reassembled the motor and turned on the power, the motor ran.

I'm going to open the electric motor again and do a better job of cleaning the sawdust of the rear bearing. I think I also need to put some grease on the back bearing, but it looks like I'll be using my Shopsmith again this weekend.

Thanks to everyone who helped!

[JPG]

YaHooOOOOoooOOOoooOOOoooo!!!!!
. . .

Indeed!!!!:)

[Ed in Tampa]

Before you do burn up the motor get adequate power out there.

The fact that the lights dim is bad. The fact the breaker hasn't tripped is good.

But if it is at all practical I would run another circuit or or upgrade the circuit you do have.