Ac motor help needed

[11b30b4]

I want to first thank everyone who helped me out in figuring out the material used on different motor. As always GJ members provide sound advise and willingly share their knowledge and experience.

I am currently in the process of rebuilding a vintage Craftsman 6” belt disc sander. My build thread is here:

11b30b4’s Craftsman 103.22500 6” Belt Disc Sander Rebuild

11b30b4’s Craftsman 103.22500 6” Belt Disc Sander Rebuild I picked this sander up at an estate sale this morning for $110.00. I normally would not spend that much on a sander but in my quest to fill my shop with classic Craftsman/ King Seeley tools on pedestal stands and given the scarcity of...

www.garagejournal.com

The sander is pulley driven and is powered by a Craftsman 1/2 HP 3450 RPM Capacitor Start Ball Bearing Thermal Protected Motor model #397.19821. The motor was not tested when I purchased the sander and now, I am at the motor part of the rebuild. Before I did anything with the motor, I plugged it in to see if it runs and nothing happened.

No hum, no spin, no smoke, no nothing. I tried to spin the shaft, and nothing happened.

I am asking you guys because I am not an electrician, but I am fairly adept at figuring stuff out. I have not multi meter tested anything yet. Here is what I think I know:

• No spin with a hum normally indicates a bad capacitor but I am not hearing a hum and a hand spin of the shift does nothing to run the motor.
• After opening up the motor I noticed two of the wires had bare spots. I spliced and fixed these two wires with 16 gauge silicone lead wires.
• Retesting showed no change.
• Possible issues could be:
• bad switch
• bad thermal protector
• bad capacitor
• bad windings
• bad power cord
• short elsewhere in motor
• an evil wizard has cast a spell of disenchantment on the motor.

I will try to test the motor for continuity and the capacitor with my digital multimeter tonight. I do not know how to properly check each of the lead wires so some recommendations would be appreciated. Here are a few pics of what I am dealing with and I do not have a wiring diagram and I would not know how read the diagram if I had one. I have looked for one on vintage machinery and could not locate one for this motor.

The odd thing for me is that the motor acts like there is no power getting to it. I can replace the cord and see if that changes anything. I am wondering if I can bypass the switch and then the thermal protector to eliminate them as possibilities?

Anyway, that is what I am dealing with.

Worst case, I replace the motor, but I would prefer to keep the vintage motor with the sander.

Thanks in advance.

Jeff

 

[Steve from Socal]

Try wiring a cord past the thermal switch,

 

[Lightning rod]

Check the simple things first
(1) check power cord
(2) check thermal switch

with no noise of any kind, you are not getting power to the windings

data on the switch(s) can be found here

Klixon Motor Protectors

 

[Cruzan80]

As others have said, start by checking via direct power. You can also multi-meter for continuity (should have some between lines). When it is plugged in and "on" does the shaft spin freely, or is it "locked"?

 

[11b30b4]

Guys yall rock!

Steve in SoCal, Lightning rod, and Cruzan80, thank you for the suggestions and the link to the Klixon Motor Protectors. I hope my Klixon has something on it that tells me which model it is.



So tonight, I will use a replacement power cord and bypass the Klixon and see if I can get this thing to spin.

Cruzan80, the shaft spins freely with the power on just like its off so I really do think there is a power issue. The original cord is a 2 wire older cord so its possible there is a break in the cord or something but I also assume that if there is a problem with the Klixon, that would prevent power from getting to the motor since its wired between the switch and the motor.



I will let you guys know what happens. Thanks again for the help.

 

[larry_g]

First of all if you don't find a problem and start changing things you may fix the sysmptom but nt the problem.

Start with ohming out the cord from the blade to the first junction.

When that is good then clip the ohm meter on the blade for the black wire.

Then start down the line at each junction, starting with the one on the out of the switch. this checks the switch.

If good then move on the the next junction on that wire. Do this till you lose continuity.

Just follow step by step till you get an open and you should find the problem. Once you find the problem then you can try wiring around the problem to confirm a bad component. It's much safer to check things with the ohm meter than it is messing around with live components.

Also check resistance between the wires and the housing, Nothing should be electrically connected to the housing.

lg
no neat sig line

 

[Cruzan80]

The reason I was asking out it "locked" when power on is if it was out of balance or a winding was bad, it can cause it to lock up. I would start by checking continuity from each post to another, and then to the motor she'll. This helps identify windings. looks like 2 and 3 are your incoming leads, and then 5 is to the start winding. You may have to actuate the copper sticking into the center, or otherwise "open/close" whatever works for the start windings. Once you figure out leads, check both sides of the thermal reset. If that is good, keep moving backwards until you find a break. is there a switch internal to the motor (baseplate), or is it separate?

Either way works, I just prefer to start at the motor as I frequently replace cords. Larry is starting from the other end.