Jet JJ6-CS Jointer: Motor Popped and Smoked

[Taylor Craig]

Hey everyone. I've been lurking for a while and finally hit a problem I couldn't get direction on via the search bar

Picked up a used Jet JJ6-CS a few months back. It was vibrating and squealing quite a bit so I finally got around to taking it all apart. Replaced the belt with a link belt, removed all of the rust from the pulleys, bed, etc.

Plugged it in and was happy to find that the squealing wasn't present on start up. I left it running for about 30 seconds -sometimes the squealing wouldn't start until it had been on for awhile- and all of the sudden I heard a loud pop and saw a plume of smoke coming from the motor. I checked the wiring and everything visible looked good (no signs of heat), then I started feeling around on the motor. The lump where I believe the capacitor is at felt pretty hot. Hotter than the rest of the casing to be sure.

The other things I can think of:

• There was a smell. Sort of oily, but not overbearing
• When I tried plugging it back in, it does nothing. No hum. No movement.
• I did lube up the bearing -- Could it have made it's way back deeper into the motor
• There was a flimsy ring of metal on the outside of the cooling fan that looked to be brushing against the fan. I bent it back a little bit just in case it was contributing to the excess noise

Motor details:

• 3/4HP
• 60HZ
• 115/230
• 12/6 Amp
• 3400 RPM
• 2 Pole

The bit of help I'm asking for is if someone can tell me if the motor is fixable, or what a suitable replacement is. The ones that I've found that match those specs are all around $300, and that price, it feels like it makes more sense to buy a 6" Grizzly.

Any help would be greatly appreciated. Let me know if I can provide any further details. Seems like I'm going to have to take the motor off the mount anyway, so if I need to crack it open and take pics, that's doable.

[Matt Day]

Check out the capacitor. If you're lucky that's the problem and it's a $5 fix. If not and you let out the magic smoke your windings might be toast.

[Bruce Wrenn]

Check out the capacitor. If you're lucky that's the problem and it's a $5 fix. If not and you let out the magic smoke your windings might be toast.

When you get smoke only, the windings are trash. But the pop you heard was the cap puking it's guts.

[Taylor Craig]

When you get smoke only, the windings are trash. But the pop you heard was the cap puking it's guts.

Thanks to you and Matt for the direction.

I do have one question, and I'm the first to admit that I really have no applicable knowledge, but does an extra alarm (so to speak) go off when it does absolutely nothing when plugged in and trying to start it. The few contributions on here that I've seen where the cap has been the problem, there's reference made to the motor still humming. Maybe I misunderstood.

All in all, the timing of this whole thing is just very peculiar. I probably put 2 hours of run time into the machine before "restoring" the cabinet, bed and other cast iron pieces to a better state.

[Rich Riddle]

I would look at a capacitor but the truth is a motor that size isn't all that expensive. You could easily find one used with those specifications. I always have a motor or two extra laying around the shop.

[Andrew Hughes]

I just went thru something similar with my bandsaw.Lots of smoke very nasty smell.My run cap gave up its guts.Most likely from some power surges I had while the saw was running.Several years ago.
A new one set me back 40 bucks.
The start and run caps have different values.All the details can be found with a couple clicks.
Good luck

[Dan Hahr]

As said, most likely just a capacitor. Probably the start capacitor. Pull the cover, and you'll probably see it swollen and leaking fluid. Get an exact replacement from Jet for 30-40 bucks or the same spec and size either online or at a motor shop and you will be good to go. It's a simple fix, just learn how to discharge it before you shock yourself.

Dan

[Frank Pratt]

Probably not just the capacitor. If it's just the cap, you'll still hear the motor humming because there is still power to the run windings. No hum at all means no power to the run winding (probably cause it's burned out) & the starting winding is getting no power cause the cap is gone. Fractional horsepower single phase motors are rarely worth repairing at this stage.

[Taylor Craig]

Probably not just the capacitor. If it's just the cap, you'll still hear the motor humming because there is still power to the run windings. No hum at all means no power to the run winding (probably cause it's burned out) & the starting winding is getting no power cause the cap is gone. Fractional horsepower single phase motors are rarely worth repairing at this stage.

Pulled it apart and indeed it is the start capacitor. Is it worth investigating the switch (or wiring)? That's the only other component I can see keeping the cap in circuit long enough to blow it.

I take it from your advice that if I replace the start cap, I'm likely to blow it again.

Edit: I had to take the motor off from the switch when I was cleaning everything up. Looking at how this is wired, I'm wondering if something is backwards on here and if that would've caused the start capacitor to remain in circuit. It's strange. The wire coloring more closely resembles the JJ6CSX -- I have the JJ6CS. Seems as though a repair was made with a prior owner...?

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[Charles Lent]

The centrifugal switch is inside the fan end of the motor. You aren't there yet. Sometimes the start capacitor will blow on it's own, but it's not wise to just replace the capacitor without checking the switch. You are going to need to remove the fan cover, then the fan, and then the end cover of the motor. Mark across the seam between the motor barrel and the end cover. A scratch in the paint, or a marking pen will do it. This is so you can put the end cover back on in the same orientation. There will be several long bolts running all the way through the motor around the perimeter of the covers. Remove these. Then use an old flat blade screwdriver and a hammer around the seam with the screwdriver tilted at 45 deg to drive the cover free of the motor cylinder.

The centrifugal switch is in the fan end cover. It's just an open single contact switch, but the contacts need to be clean and not welded together. There should also be some spring tension holding these contacts together. The rest of this switch is on the motor shaft. It consists of two spring loaded weights that swing out away from the motor shaft as the motor comes up to speed. They move a plastic collar on the motor shaft and it's this collar and it's ability to slide on the motor shaft that is usually the problem. Clean the area of the motor shaft where this collar needs to slide. It will usually take buffing with a strip of fine emery cloth. You want it shiny and chrome in color. Then lubricate this area of the shaft with a very thin layer of synthetic grease and then wipe it off with a rag. The little bit left will have gone into the pores of the metal and will be sufficient to last another 10 years. You don't want any visual evidence of this grease to be left behind. It will reduce corrosion and lubricate the collar for a long time with just this tiny amount. If you leave any thicker or in gobs behind, it will fly off as the motor spins and possibly create other problems.

Now re-assemble the motor, fan, and fan cover. Match up your line or scratch to get the cover oriented correctly. Then test the motor. As you start and stop the motor you should hear an audible click as the motor crosses about 500 rpm. If you hear it while the speed is increasing as well as decreasing at about that speed the motor should be ready to use. If you don't hear this click and the motor seems to have a loud angry sounding whirring hum, the start capacitor is still engaged and you have not repaired the switch. Turn the motor back off quickly or you will damage it. Then repeat the service steps to correct the problem, looking for the reason why the collar is not sliding as the weights swing out from the shaft.

Charley

[Frank Pratt]

Yes, the capacitor is done, but the fact that there is no hum at all means there is something else wrong. The run winding is connected directly to the motor terminals with no capacitor or switch in between. No hum means no current flowing through that run winding. Hopefully it'll be something as simple as a loose lead.

When it ran for the 30 seconds, did it sound right & did it come up to speed as it should?

[Taylor Craig]

My frame of reference is a little skewed on it. It ran fairly rough prior to me changing the belt, aligning the pulleys and just generally getting the grime off of everything.

With that said, when it was running I was a bit on guard. It seemed aggressive/more powerful (but smooth).

If a neutral and a hot were flipped, could it have started and overloaded? I haven't popped it open far enough to trace the wiring, but it looks like whoever repaired it last went a little outside of the playbook. As I said, when I pulled the wiring off the on/off switch, I feel like I remember the wires being reversed but I shook it off since it had been working correctly previously. I feel like that's my last (unlikely) hope. The switch is something that feels a bit out of my depth (from what I understand). $130-150 for a new motor vs. $600 for a brand new machine feels like the impending decision point

[Frank Pratt]

Tough decision to make. It'd be nice if you could find a used motor that could be made to fit.

[Dan Hahr]

I'd take off the fan cover and just clean the switch. It's not that hard at all and probably needs it. Sawdust can cause one to stick. Blow it out really well with air. Take the belts off when running it. It will be much quieter and you should hear the switch open and close. If it runs in the right direction and ran fine before, you are probably good to go. If worst comes to worst you can always upgrade to a 1 hp. It might have a run capacitor also that needs replacing.

Just take it apart and see. It's not that hard.

Dan

[Bruce Wrenn]

When cap puked, did by accident breaker in power box kick out? It has happened. Plug a known running machine into recpt. to check it. If recpt. is good, get the FREE VOM from HF and start looking for break in circuit.