Shopsmith Forums

I would not suggest zip ties to bind the windings. Use a waxed cord available from a lot of craft supplies such as JoAnne stores.
As JPG said, releasing the smoke in any electrical/electronic device is not a good sign! If the smoke had a waxy smell, like candle wax, you may be lucky and only have a shorted capacitor.
Check the ends of the cords, if they are burned through you may have a serious problem but if they appear cut like someone cut them previously to do a repair you might be lucky.
Also, as has been said, pictures are worth a thousand words so if you can please post a few.
Bill V

Before I spent a lot of time replacing the capacitor, I would make some resistance measurements of the windings and from each of the windings to the motor case.

The waxed string is most often damaged by excessive heat build up in the windings. That occurs when there is a short in the windings. A short either winding to winding or winding to case.

dusty wrote:Before I spent a lot of time replacing the capacitor, I would make some resistance measurements of the windings and from each of the windings to the motor case.

The waxed string is most often damaged by excessive heat build up in the windings. That occurs when there is a short in the windings. Ashort either winding to winding or winding to case.

A 'winding turn to turn' short is impossiple to determine by measuring. Running the motor will reveal it though(the winding will burn up).

The 'smoke being white' may be a good sign.

Short(any reading less than a megohm) from either winding to case is cause to convert the motor to a boat anchor.


Any resistance measurement must be done with all leads flying(not connected to anything including internal terminals).)


FWIW, windings that have been 'hot' will be darker color brown as long as the insulating varnish is not broken down and are salvageable.

Windings burned more severely are also salvageable with reapplication of formvar high temp insulating varnish, but are a dice roll. The most likely place for a breakdown is internal(hotter[maybe]) and inaccessible, but exposed wires have oxygen present and no heat sink and can burn(varnish) quicker. Fortunately the wires are not packed as densely out of the core so new insulation(varnish) application is possible. A thin line there!!! Being Irish may help!:D

Thanks guys for the advice. I've started to take a closer look at the problem. The capacitor is definitely trashed. The relief port is blown out, so I think my initial thoughts on where the goo came from is correct. The coils are still copper colored, not black. I've tested all of the wiring and the coil to the motor case, and there are no shorts, that I can find. The switch operates fine by hand (checked w/continuity). I also put the ohm meter on all of the cables and contacts that i can reach/find. The resistance between the two power cables (blue and white) reads 0.8 ohms. On the switch, the resistance is 0.3 ohms, when the switch is closed. The resistance between the blue power wire and the black capacitor input wire is 5.4 ohms, the white to black (as above) is 5.9 ohms. Both wires show an open circuit to the black output wire of the capacitor.

Hopefully you guys understand all of that as I'm not very familiar with the terminology used for electric motors. I've also uploaded some photos, see: http://www.flickr.com/photos/23959245@N05/sets/72157635121420237/. Hopefully the pics will be somewhat self explanatory.

So now that I know that the capacitor blew, the question is why? Did it just go bad, or was there a short somewhere that caused it to blow? I don't think that I'll be able to pull the fan sheave off so I can pull the rotor out of the motor to inspect everything more thoroughly than I already have.

The windings look to be OK from your pics. The little bit of black stuff that I see looks like some burned debris from the capacitor. The waxy paper discharge is part of the insulator between the plates of the cap and the waxy substance is most likely some of the dielectric.
Why does a capacitor go bad? Age, atmospheric conditions, very dry environments and a host of others. If I had a real answer to the question I would have fixed it and retired a lot more comfortably!!
It looks like you may have a bit of the Irish in ya as JPG suggested.
Bill V

wa2crk wrote:The windings look to be OK from your pics. The little bit of black stuff that I see looks like some burned debris from the capacitor. The waxy paper discharge is part of the insulator between the plates of the cap and the waxy substance is most likely some of the dielectric.
Why does a capacitor go bad? Age, atmospheric conditions, very dry environments and a host of others. If I had a real answer to the question I would have fixed it and retired a lot more comfortably!!
It looks like you may have a bit of the Irish in ya as JPG suggested.
Bill V

Ditto!

I took the motor over to the local shop today to see what they could do. They agreed the capacitor blew, but they said that they usually blow for a reason .They told me to buy a capacitor from grainger, install it, reassemble carefully, and cross my fingers. They gave me the old line "they don't make 'em like this anymore" and told me that if I left it it would cost a couple hundred bucks and they wouldn't be able to find any parts for it anyway. They also recommended that I not retie the windings as they've been set for a long time and are not likely to move now they also recommended that I not clean out the goo that the capacitor sprayed all over (wouldn't hurt anything and may break something else in the cleaning process). They then lubed up the centrifugal switch component on the rotor shaft and put a couple of drops of oil in the back cover where the rotor shaft sits and wished me luck.

I'm thinking about removing the front cover tonight to get a look at the other end of things to see if there is any visible damage and to check the bearings.

This whole episode is really disheartening as it is clear from the inside of the motor that it was barely used. There is absolutely no sawdust in the motor at all, nor is there any markings on the machined surfaces that indicates any use at all.

tvidnoviciii wrote:This whole episode is really disheartening as it is clear from the inside of the motor that it was barely used. There is absolutely no sawdust in the motor at all, nor is there any markings on the machined surfaces that indicates any use at all.

This may not actually be a bad thing after all. I have seen several instances where capacitors go bad from sitting unused for extended periods. I'm not sure what is involved internally that causes this, but things may not be so bad. I'll keep my fingers crossed for you.

So I took the front cover and rotor off the motor last night to get a look at the coils in the front of the motor. I've posted a couple more pics at http://www.flickr.com/photos/23959245@N05/sets/72157635121420237/. The most telling thing is that there appears to be some evidence of overheating in the coils that are at ~2:00 and 8:00. I assume those are the starting coils and may have either been affected by the explosion of the capacitor or a short in them is what caused the capacitor to explode. The heat related damage seems to be limited to some burnt cords and a blackening of the lacquer coating on the coils. I tested for shorts to the case and was not able to find one.

If the damage was caused by the capacitor, then replacing that item should fix the problem, however, I am worried about the functionality of the centrifugal switch. Is there any way to test it other than closing the circuit manually, which I've done?

tvidnoviciii wrote:So I took the front cover and rotor off the motor last night to get a look at the coils in the front of the motor. I've posted a couple more pics at http://www.flickr.com/photos/23959245@N05/sets/72157635121420237/. The most telling thing is that there appears to be some evidence of overheating in the coils that are at ~2:00 and 8:00. I assume those are the starting coils and may have either been affected by the explosion of the capacitor or a short in them is what caused the capacitor to explode. The heat related damage seems to be limited to some burnt cords and a blackening of the lacquer coating on the coils. I tested for shorts to the case and was not able to find one.

If the damage was caused by the capacitor, then replacing that item should fix the problem, however, I am worried about the functionality of the centrifugal switch. Is there any way to test it other than closing the circuit manually, which I've done?

You can hear the switch mechanism make mechanical noise. If you 'tested' the switch manually(operating said mechanism) then it will likely work. That said, the Emerson motor start switch moves a very small distance. A more common problem seems to be the opposite(crud prevents them from 'making').

It is possible(conjecture) that a shorted switch created a prolonged application of power to the capacitor or unusual over voltage conditions that caused it to fail. So it would indeed be wise to verify it is opening.

Bringing out a couple of wires(temporary) connected across the switch would allow you to verify switch opening. When closed, there is no voltage across it. When open something less that 250V(ac) should be present.


P.S. What is that orangeish stuff on the roter and end cap? That may be a clue!