How to Fix a Noisy Oven - When Shaded Pole Motors go Bad
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- Опубліковано 10 вер 2024
- This is a short demonstration of how to replace a noisy fan caused by a seized shaded pole inductive motor in an oven. The details of how this very common motor works and its design limitations are discussed. The oven shown is a Kitchenaid Superba oven, which I believe is made by Whirlpool. However the technique shown applies to many electric fans and motors.
The other video showing how to tear down the oven to replace the thermal shutdown fuses is here
• How to fix a Kitchenai...
If you decide that you only need to replace the shaded pole motor, there are many options including Ebay. A classic older style design was the EM670, which may be a helpful search term if your motor has no specific markings.
This is an amateur demonstration, offered for free but with no guarantees as to safety or accuracy. Never trust any one source for critical information. Before doing any home repair, you need to decide whether you are willing to accept inherent risks that are inevitably intertwined with such repair. Any misadventure you encounter if you decide to accept those risks are your responsibility.
Thunderclap sound used under Creative Commons 3.0 license, done by RHumphries at freesound.org/p...
Music by Cold Funk - Funkorama by Kevin MacLeod is licensed under a Creative Commons Attribution license (creativecommon...)
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The diagram at 3:11 showing air flow was taken from the OEM repair manual. I've always been a little puzzled by the direction of the black arrow showing air being drawn toward the blower. In fact the part I call the 'snorkel' is placed on the blowing side of the fan, so the arrow should weakly point the opposite way, to exit out the front. That way air from the oven compartment would be drawn out by a weak Venturi effect. Practically speaking, it is obvious that air blows out from the front of the cabinet so the red arrows are accurate. I wonder if this part was redesigned when the manufacturer noticed warranty failures from overheating when self cleaning.
Excellent presentation. I am fixing a mini fridge and discovered that the condenser fan has failed. I then found your video "How to investigate and fix a fridge that is too warm." Your comment at 6:24 in that video led me here because I was interested in learning more about these motors. First of all, you helped me confidently diagnose my mini fridge. Secondly, and quite coincidentally, I have a KitchenAid oven from the same family as yours (but with integrated microwave). If I ever need to replace a motor on it, I know where to go on UA-cam now. Thanks for your thorough and no nonsense presentation.
Thanks, man! This week I'm doing a video on a failed PSC Motor, which is a step up the ladder of AC induction motors from the shaded pole design. The people who designed these devices were brilliant.
It took 4 years for You Tubed to figure out that this is what I prefer to watch and learn from. Unfortunately I don't think You Tubed can be fixed. Subscribed
Thanks for your encouraging words. Likewise as an author I've found that many of what I think are my most interesting videos get relatively few views, like this one. This month I'm doing one on integration of two battery banks in a boat, and it will probably be the same, lightly received. As narrow as the google search audience may be, hidden inside will be many principles regarding how to size wire, how to evaluate alternator output, how to fuse circuits, how to use an inductive ammeter, and the differences between AC and DC systems. Like most teachers I'm happy to find the rare individual who is actually interested, ha ha.
Dave
Awesome stuff! Always great to see someone take the time to appreciate the ingenuity of those who came before us:
Great video. I had the same issue with bearings in the two convection fan motors in my oven causing the rotor to rub on the stator. It's fascinating how this motor works.
Fascinating, I agree! Today I'm completing a video on failed PSC motors in a dehumidifier. They are similarly intriguing. Tesla, and the guys who invented newer electric motors, were brilliant. Thanks for stopping by!
Helpful video - thanks. Had a similar failure with a Kitchenaid range cooling fan. Noisy, then just humming. Unfortunately, whirlpool no longer provided a service part, none on eBay, search internet for 1500rpm, 3/4 inch thick lamina stack shaded pole motor.... nothing!! Motor did not turn smooth so I took off the bearings, found the rotor had "gunk" on it, cleaned it, oiled bearings and reassembled - done! Sometimes you just need the confidence to tear into it and try - your video helped me get that.
Great tear down and explanation Dave. Reminds me of last Christmas when I was replacing the noisy convection fan on my oven so we could cook the turkey relatively quietly without the bearings growling at us. Thanks for sharing 👍
Rob, thanks for stopping by! I know what you mean, pressure from the wife to make Christmas perfect motivates us all, ha ha. As you know I'm working through videos on your professional auto repair channel, well worth the effort.
Fantastic explanation Dave along with a great repair! :)
Thanks, Terry! I know you worked with motors like this for a living, it's kind of you to drop by and have a look.
spelunkerd it's always a pleasure Dave to drop in and watch videos on your channel. I always find your videos very informative for your viewers. 😀👍
Thank you for the excellent explanation of your repair I had a similar problem with the blower fan behind a buck woodstove. the bearings were making an awful racket and you can imagine the difficulty involved in pulling out a 300 pound stove from built-in stonework masonry.
Yeah, I've got one like that, too, ha ha. Thank you for stopping by!
These shaded pole motors are awesome. This radial fan probably would have needed nothing more than a bit of good oil on the bronze bearings to keep running for decades. When making repairs, I always try to start with the simplest thing, for example with oil.
That's a good point. I did oil the other bearings while in there and the oven is still going strong!
@@spelunkerd Thanks. Yes, oil extends the life of many things many times over. Of course only if it is not resinous, preferably synthetic oil.
Great video, enjoyed the info
Well done. Great production will recommend
Excellent description and repair dear sir as always. Such motors are very common in small applications but they are poor in efficiency compared to capacitor type single phase counterparts. Best regards.
Wonderful point, I'm glad you brought it up! I had a similar remark embedded in the video, but it was cut from the final edition because I've been struggling to make my information delivery more snappy. As you say, it takes power to spin current in endless circles around the shading loops, wasting energy as heat. Also the strength of each pole is reduced when trying to confer bias to rotation, even though once the rotor gains momentum there isn't much bias needed. Thank you so much for watching my videos, it's great to have educated, thoughtful commentary.
My frend brought round his fan assisted ovan (similar to yours), it would kick out the electricity for no apparent reason.
I found no problems with the wiring and nothing had excessive current passing, so i checked for earth leakage to the case, oh yes it leaked a little.
The bottom element under the floor of the box had the leak.
When pulled out to inspect it i had a surpprise.
The outer metal tube had melted and the center element core was sitting on the outside sheet metal casing, no wonder the mains tripped when it was warming up.
Check your unit for earth leaks if it plays up :-)
Those ovans also tend to blow out there elements, holes can appear in odd places, not always easy to see eather.
The discription i use for those motors is "Record player motors", it's just the way i remember the type.
Now i understand the motors much better since watching your smashing video :-D
Another one of your excellent contributions to a thread. I was getting a PF shutdown with the oven, and I wondered if they were separate problems. In the end, replacing the fan fixed that problem, too. Perhaps I had stray current reaching ground, as you describe, though I couldn't find an obvious short and my non GFI circuit breakers never tripped. I wouldn't expect it to be from the squirrel cage where it was rubbing the side of the laminate core, but maybe that induced an asymmetry of the magnetic field. The oven itself seems to have a protective shutdown with either stray current or just temperature.
I think my fusebox has a seperate earth leakage circuit and R.c.d/over current breakers.
They work well, but you cant get away with minor faults lol.
In the "Old days" we had a small wooden box with white pot blade fuses, there were screws so you could change the fuse wire.
High tech LOL :-D :-D
I have a very similar oven, but with the ultima speed cooking feature. Good info. for any future fan problems. Thanks
Yeah, the model I have is a little prone to overheating with self cleaning, I wouldn't be surprised if you stop by one day in the future. Thank you for watching.
I admire this man.
BTW I am about to check the Fuse as mentioned from the last video. I checked the fuse on the back last time and it was fine, so I think its the one in the top.
I have this problem at the moment which I plan to fix tomorrow as the old oven has working shaded pole motors
How can these motors possibly go bad? I had one go bad in my freezer, it was a small shaded pole motor. I couldn't wait for the new fan to arrive in the mail, so I retrofitted a 1.2 amp commercial 120 volt metal "computer fan" with a digital hall sensor control board inside of it, which is a very expensive ball bearing fan for large commercial equipment cabinets; you can hear it spool up when the freezer/fridge kicks on, because it's a ball bearing fan with a metal frame and no rubber dampening like the original freezer fan. The freezer is noisy now, but the ball bearing high speed fan is a beast. I'm hesitant to put another "shaded pole" motor back into the freezer, because the new one I purchased was about $17 and it's so underwhelming, I expect it to fail right away. But how can something so simple fail? Computer fans with their hall sensor and transistor power circuit board inside of them, never seem to fail, despite their increased complexity.
Its always feels good after fixing broken stuff
I know, it is like a drug, hard to stop! No wonder, whenever I save money fixing something I pour that money back into more tools, ha ha. Thank you for watching.
thanks, this helps. I was wondering if the motor could have been repaired or lubricated? The part in Canada is around $150cad
If you're sure it is the motor, you can buy just the motor and swap it out. Similar motors are available on Ebay, though it is always hard to be sure they will be perfectly compatible. You can disassemble the motor and clean it all, then put oil onto the bushings. Some of these have a felt pad that you can saturate with light machine oil. There are a few videos of that procedure here on UA-cam. However in the end there is a cost to trying to do a partial job, then failing if parts aren't compatible, or if it fails again at a critical moment like a dinner party with guests standing in the kitchen. I factored all of that into the equation and decided to get the OEM part, as you say for about 150CAD. If I had parts on hand that I could swap out without having to pay for shipping (and then wait for it to arrive), it might be a different story. Good luck!
that was a good video i think 2nd video i watch of yours first was your freezer then got me start with another youtube and that how i learn about appicance repair what the differnt with fluke 88 vs 87 i got a very good deal on my 87
Yeah, the only weakness of my 88V is the lack of RMS voltage, which isn't a big deal for me since most of the time I'm dealing with DC voltage. The new 87 has RMS, but mine is older. Great meters! I believe the 88 and 87 are very similar. Both have replaceable fuses, which I've blown a few times when doing stupid things with the ammeter side, ha ha.
good to know sure does look like same i got very lucky at find flukes 1 brand new and another almost brand new with case on craiglist so i can do amps without opening circuit. yea those fuses are not cheap at all
After finding out how much they cost, I went onto Ebay and bought a bundle of 5 Fluke fuses for the same price that one goes for at a local store. These days I try to use the inductive meter as much as I can, at least as a screen. The inductive meter is not very sensitive for AC current on the low end of the scale when less than 1A. Notice that my 0.2A reading here was lower than the actual value of 0.46A. Nice to meet you.
Dave
thanks for the tip ill have to go ebay shoping one thing about buying use fuse may be blown. i got a kill a walk if i need to do ac reading pick up for cheap. for low voltage maybe a wire and turn it 10 times then take reading from there i need to do a test and see how close it is, thanks
can we replace the bearings?and how we do that?
In these little motors there are only bushings, not bearings. Shaded pole motors come as a unit and are surprisingly cheap, so usually one would replace the motor. However in addition to the motor, there is also the fan. It has bushings, too. I replaced the whole unit; it would be time consuming to hunt around for individual parts.
@@spelunkerd my motor have 2 bearings. I have photos to show it to you. If I replace the bearings with bushings? Is it possible? I will make it more noisy you think... ?
@@djzapatwork Possible, but you have to wonder if it is worth your time. You can buy common bearings at auto parts stores, but this size must be uncommon. Bearings are better than bushings. If it already has bearings and I wanted to upgrade I would try to find matching bearings. Often they have a part number and manufacturer, if you look with a magnifying glass.
@@spelunkerd today I look at the internet and I find that a new one motor+fan it cost about 20€.i will buy a brand new. Thanks for your time.
Heard once (but can't confirm) that it was old man Tesla that came up with the Shaded pole. The shaded pole Wikipedia entry seems to be lacking history of the device...
Yeah, when researching this video I looked for some history. Evidently Tesla's first work pursued the multiphase, multipole array to create rotation, though they say that Westinghouse then went on to find a simpler motor that would work with single phase over the ensuing decades. As you say, Wikipedia is a little murky as to who actually thought of the shaded pole idea first. Tesla would be a good guess, ha ha, he was astonishingly prolific and intelligent. I found a review article describing shaded pole motors in 1936 so the story was already well developed before then. Much of the research was proprietary, so I guess it's not a surprise to find that full documentation is scanty. Thank you for stopping by!
It drove me crazy that you didn't lube/add oil to the bearing oil reservoir.
That's a good point, and I'm glad you brought it up! For the one that failed, I didn't think it would matter and I had already committed to replacing it. Once those bushings are cooked, they aren't easy to reclaim, and lube doesn't work for long. This oven has three shaded pole motors that are easy to get to, plus two more. Off camera, on the others I did put a few drops of machine oil onto the felt oil retention pad around the bushings. On these, there is no actual oil reservoir aside from the felt pad pressed up against the bushing.
@@spelunkerd Thanks for the reply; I understand.
I came across your video as I was overdosing on electric motor videos as I'm lubing every motor in the house from the AC condenser to furnace blower, inducer fan, to kitchen-bathroom exhaust fans, electric space heaters, vacuum cleaners, ovens - I was shocked by just how many motors are in my house, and the number of discarded appliances by folks who don't have the knowledge to do the kinds of repairs we tackle.
I was also surprised by the replacement cost of some of these motors especially in Canada where things are more expensive than in the U.S., but it was good to learn that there are a variety of replacement fan/motors options even with ball bearings, albeit more expensive.
Speaking of ball bearings, I also came across a couple of videos of folks replacing the rear brass bushings in the ShopVac motor with ball bearings which I will also be doing - just think of the number of ShopVac motors junked annually because of worn out sleeve bearings.
ua-cam.com/video/KdTgQGFfy9o/v-deo.html
6:03 Why there is a 'tape' around that coil ????
Good question. It may be a moisture barrier or a barrier for lint or iron particles that could be magnetically pulled in after manufacture.
Just doing the devil's advocate:
If so, why there are several similar shaded pole motors without such 'tape' around the coil?
I think you are seeing less of these type motors for good or bad in 2010+ designs; example would be bathroom ceiling fans, they have unfortunately the same design flaw; lubrication. This design would last for a very long time if it had an auto lubricator. Good luck with that I know. Lack of lubrication and most importantly the inability to maintain the product. Considering the abuse they really do last a long time and it is dependent on many factors. I guess what it comes down to is the inability to easily maintain the product. Mean time to failure is what manufactures go by, the error rate is determined by Quality Control. Question is do we have that today?
Wise words. As you know, getting at that felt pad to replenish the oil is not so easy, especially in motors that are hard to get to. We see this throughout industry, a pattern of fewer grease nipples and bearings with more plastic that ultimately ends up in a landfill. I hate replacing parts with inferior devices that will in turn need sooner replacement. Thank you for your thoughtful remarks.
What's interesting is that all the old consumer motors for power equipment, like small planers, and drill presses, they had a bushing motor on them. And even fan motors for large industrial squirrel cage fans, many of those motors are just bushing motors. The little felt pads inside the motor hold decades worth of lubrication. Lubrication is a problem on the small bathroom fan motors, but ultimately they fail electronically. They suddenly stop working for no reason, as if there is a programmed obsolescence built in. How is this possible? The copper winding appears to fail, but that shouldn't be possible. There is a great mystery here. I have a perfectly good fan sitting here that spins fine, but it died electronically. A shaded pole motor shouldn't be capable of failing (transformers of a similar construction have a 0% failure rate). Oddly enough, I have a very old shaded pole motor that I found from a junkyard, with a beautiful metal fan attached to it, and it works as good as new and makes no noises. I've never been able to understand why some of these shaded pole motors fail early.