# Craftsman 12" radial arm saw electrical problem



## Micah Whalen (Mar 6, 2017)

I have a craftsman 12” radial arm saw that I recently acquired. I tried turning it on, but nothing happens. No hum or noise of any kind. The blade rotates freely with no binding or grinding. The exterior is clean the interior (under the electrical covers) look immaculate. 


I have measured the capacitor and found it to be 15uf as it is labeled. I also verified proper switching continuity of the main on/off switch. I have found a manual for it, but it does not give a schematic and I am not sure how to test the remaining items I found near the capacitor. I need some help identifying what they are and some testing guidance please.


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## woodnthings (Jan 24, 2009)

*Did the saw work prior to your acquisition?*

If the saw did work previously, then you have a power supply issue. The motor will only run on 240 v. Check to see if you have 240 on the supply wire before the switch. The saw has a key lockout to prevent unauthorized use. Make certain the key is in and turned to the "ON" position. The other electrics are pretty bulletproof and rarely go bad, so I'd look for a simple wiring issue.

The small red button is a thermal overload and would just need a simple push to reset it... if it were overloaded at some point .... unlikely?


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## TimPa (Jan 27, 2010)

with the switch on and power applied, you can follow the voltage until it stops. there will be 2 incoming lines with 120 volts on each. what is the device in the box? give us part numbers of the other 2 devices. I see 2 capacitors. the 15 mf would be the run capacitor. the other will be the start cap.


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## Micah Whalen (Mar 6, 2017)

I did verify my circuit was properly supplying 240vac if that's what you meant woodnthings. I didn't see a key anywhere on the saw. If I could find that, I'll bet that must be the problem.

If that other cylinder in the right side of the pic is also a cap, I can test that tonight. I didn't roll it over to look at the label. That leaves the item above it as the last unknown item. I'm not entirely sure how the overload switch works as far as the wires. There are 2 blacks and a dark blue going to it. I'm guessing the blacks are normally closed contacts, but I don't know what the blue wire is for or goes to? If I'm right about the black wires, I should be able to just verify continuity between them to rule out the overload, right?


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## cseltzjr (May 18, 2015)

I'm pretty sure I can see the key in the picture. If I recall correctly, the key is the yellow thing inserted in the power switch. I would take the meter and look for power at and after the power switch. Be careful around the capacitors. I think those hold a big zap when they are charged up.


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## epicfail48 (Mar 27, 2014)

Micah Whalen said:


> I did verify my circuit was properly supplying 240vac if that's what you meant woodnthings. I didn't see a key anywhere on the saw. If I could find that, I'll bet that must be the problem.
> 
> If that other cylinder in the right side of the pic is also a cap, I can test that tonight. I didn't roll it over to look at the label. That leaves the item above it as the last unknown item. I'm not entirely sure how the overload switch works as far as the wires. There are 2 blacks and a dark blue going to it. I'm guessing the blacks are normally closed contacts, but I don't know what the blue wire is for or goes to? If I'm right about the black wires, I should be able to just verify continuity between them to rule out the overload, right?


If the cap was bad, you should still hear a pretty distinctive hum even without the motor spinning. If nothing at all is happening, no noises or anything, that usually points to a problem with the power being supplied to the motor. I'd grab a multimeter and check the main power switch, the overload and the power lines leading into the motor to see if you've got power


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## Tennessee Tim (Dec 15, 2010)

The reset button (overload protection) is probably tripped. Some reset easily (lightly) and others need a HARD push!!!! I've reset several "burned out" saws and they keep on ticking (It done it's job!!!). Most have a audible click when resetting.

12".....sweet!!


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## Micah Whalen (Mar 6, 2017)

OK. So I was able to spend some time on this over the weekend. There is no key at the switch. I did continuity measurements at the overload. All three connections (2 blacks and a dark blue) measure 0 ohms to each other. I would expect the overload to function by opening between at least 2 of the contacts, so I think we can rule this item out. This pretty much leaves the item on the right of the pic attached, which I believe is the relay on this data sheet: http://www.sensata.com/download/4cr.pdf

I suppose I can measure and verify the coil is not open and the NO contacts are not shorted. Has anyone seen one of these go bad?


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## Catpower (Jan 11, 2016)

The part you are wondering about is a potential start relay, as the motor speeds up the back EMF or voltage created by the motor will open that relay to drop the start windings out of the circuit.

Even if it was bad the motor would still hum or try to run

If you have an ohm meter if you can disconnect the three wires running to the motor windings, between the common and run windings you will get the lowest reading, between start and common you will get the second highest reading, and between run and start you should get a reading of equal to the two reading between the common and start and common and run. If they don't add up the motor is toast 

But I too would bet it is the over load


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## Jig_saw (May 17, 2015)

If the motor is not humming and the power supply is good, then the windings are gone. Best to get a replacement motor.


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## sunnybob (Sep 3, 2016)

If you are seeing zero ohms between all leads there is a dead short.

Disconnect the mains led and test that seperately, between terminals inside and the plug You should read infinite or very high numbers ohms.
DO NOT ohms test an electronic circuit, you;ll get all sorts of weird things turn up.

Then disconnect the motor from the electronics and test those leads. If you find zero anywhere on the motor it needs a rewind. Any tripped overload would show infinite resistance on that circuit.


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## Tennessee Tim (Dec 15, 2010)

Micah Whalen said:


> OK. So I was able to spend some time on this over the weekend. There is no key at the switch. I did continuity measurements at the overload. All three connections (2 blacks and a dark blue) measure 0 ohms to each other. I would expect the overload to function by opening between at least 2 of the contacts, so I think we can rule this item out. This pretty much leaves the item on the right of the pic attached, which I believe is the relay on this data sheet: http://www.sensata.com/download/4cr.pdf
> 
> I suppose I can measure and verify the coil is not open and the NO contacts are not shorted. Has anyone seen one of these go bad?


The key is the yellow tab in the middle of the red switch...pull it out and it won't operate.

Looking at the original pics the reset button appears to be tripped out....IF I can I'll check the one at my shop on the amount it stands out. PUSH HARD!!!


IF it were mine (I'm comfortable checking electrical circuits) I would pull the blade off for safety reasons AND put a protective cover over spindle and check connections with power on with volt meter. It's hard to check ohm in a switch or overload protection if wiring is connected (could false read).


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## Tennessee Tim (Dec 15, 2010)

I checked....on my Craftsman the overload reset is flush when set to run NOT standing out....I overlooked it due to I thought it did stand out a little.....I pushed on it BUT it had little to zero movement. I believe that's your issue....the last one I reset it took a second try due to I didn't push extremely hard to reset.


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## Pineknot_86 (Feb 19, 2016)

I would use this as an excuse to buy a new and bigger saw. Any excuse is good in this case.


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## gmercer_48083 (Apr 9, 2016)

This link may help you identify the parts. http://www.searspartsdirect.com/model-number/11323301/0247/0744500.html


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## Tennessee Tim (Dec 15, 2010)

Micah, did you get it running????


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## Micah Whalen (Mar 6, 2017)

Despite the fact that I never heard the thing reset all the times I mashed it, I guess it was the overload. Because when I went to power it on today to test voltages live, it began to spin up the blade. However, it almost immediately blew the 5 amp fuse inside the 110 to 220 v converter I had it plugged into. Next thing for me is to wire up an actual 220v circuit in my basement to really run this thing.


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## Pirate (Jul 23, 2009)

Micah Whalen said:


> Despite the fact that I never heard the thing reset all the times I mashed it, I guess it was the overload. Because when I went to power it on today to test voltages live, it began to spin up the blade. However, it almost immediately blew the 5 amp fuse inside the 110 to 220 v converter I had it plugged into. Next thing for me is to wire up an actual 220v circuit in my basement to really run this thing.


110 to 220 converter? 5 amp fuse? Sounds like you need real 220 power.
I would plug into a real 220 outlet and see what happens.

What is 110 to 220 volt converter?


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