Three Most Common Motor Fixes Anyone Can Do; Ultimate Guide to Electric motors ; #070

I took a look around my shop and I realized that the capacitor store induction motor is by far the most widely used in power tools at least at the DIY level made my air compressor my shop vac my drill press my table saw they all have passed their star induction motors and they all have the same weakness the capacitor this guy clamped in my workbench is in fact a capacitor star induction motor that I took out of a washing machine here in the US if you live in another country your washing machine may have a universal motor in it so there are some some differences there first I'm going to power this guy up with the capacitor disconnected in general when the capacitor has failed the motor will hum like you just heard but it won't spin and especially won't spend under load but if I start it and give the motor a little push let's see what happens [Music] alright so if your motor will only start by push starting then you are having a problem with your capacitor and you resolve that by simply replacing the capacitor so in this case I've disconnected it ahead of time but if we go ahead and connect this working capacitor motor should start properly [Music] so again most power tools have a capacitor in order to help the motor get started and I'll put some pictures on your screen for you so that you can see where you can find these items they're almost always connected directly to the motor now of course this is sort of this is something I took out of a washing machine and in appliances the capacitor may be stored anywhere in the machine sometimes it's put way up in the top and then it's just a wire run down to the motor in terms of what kind of capacitor you want to use a capacitor designed for AC so capacitors that have a little stripe on the side in fact I'll show you one all right I grabbed a few capacitors just to show you the difference so this one is a capacitor designed to work with AC current but this one is called a run capacitor it usually has a metal cam like this and it's filled with oils so that it can handle the heat of being constantly connected to the circuit this is not usually the capacitor that you're replacing although some capacitors are induction motors we'll have two capacitors they'll have a star capacitor and a run capacitor and if you're having problems with your motor starting I will go ahead and replace both I wouldn't fool around with just kidding one especially considering the cost is worth it to go ahead and replace both of them at the same time this one is also a star capacitor just like this I kind of brought this one out to show you that sometimes they come in different shapes and this one is a polarized capacitor and you see the little stripe on the side which tells you which side is negative you do not want to hook this up to AC current or a little explode and we don't want that you could just search the web for something like motor start capacitor or I've even typed washing-machine capacitor and I got good results from that they come in different sizes in general the actual capacitance doesn't matter a whole lot so don't obsess too much of that what's really important is that the voltage is high enough so for example you can use a capacitor designed for 240 volts on a 120 motor but you can't go the other way around you can't use a capacitor designed for 120 on a motor using 140 votes if voters will be too high and it'll damage it'll destroy the capacitor this is by far the most common problem with the motor and in fact before I check that I would check everything ahead of that in the circuit so you need to check your circuit breaker you should be checking an outlet that you're using you might want to plug it into a different outlet on a different wall just to make sure they're wired together and check any switches in the path because all of those items are actually more likely to fail the photo motor itself fails but once you've checked all the upstream stuff I would look at the capacitor as the first thing that might be wrong second thing we need to look at is motor brushes so I'm gonna pull my DC motor over let's get this guy out of the way next up is the permanent magnet DC motor as you can see I've cut away a section here out of this motor so that you can see the inside I took this motor out of a treadmill but any Universal motor or brush DC motor like this will have this a similar set up so let me bring in a little closer so that you can see what it's supposed to look like and then we'll talk about the problems most motors like this have access holes through the bottom that allow you to see into the inside and of course we've got a big nice wide opening so that you can look directly at the brush now if you want to remove these brushes you just unscrew this little cap and these guys come out like this and if you search for a motor brush then you can find something like this they're really easy this is just made out of carbon it's electrically conductive and this is how the motor gets the electricity to the rotor here so let me fire this up so that you can see what it's supposed to look like so this guy operates up to 90 volts and so as you can see if you look right along here just kill that power there was maybe just a tiny little glow and the corners where the you know contacts are switching to the next contact but there's very little sparking here generally if you're having problems with your brushes the motor will start to run a little hot you'll see sparks through these little openings in the bottom and if you look really closely sometimes when it gets really short you get big electrical sparks there and that lets you know is time to replace the brushes as you just saw a minute ago they're super easy to replace you just unscrew it pull it out push the new one back in and screw it back down now the next problem could be found on any motor type and that is issues with the bearings this guy I've already removed the screws so that I could easily pull this little section out but I also wanted to show you on this other motor that often if you need to get to the bearings you were just unscrew what's called the in bills and they'll always be you know four or six fasteners here on the end you'll unscrew those and then this end cap will pop off the same thing on this side so that you could access the bearings on each side all right let's pull this guy off all right now again this end though would normally be a complete circle but you get a better look at the motor brushes there and where the two wires come in and touch and now you can also see the bearing on the end of the shaft it's gonna take to hold shaft out and goes that a permanent magnets grabbing the motor there or the rotor so you can see you North in your South Pole and there's the other end bill and that's pretty much it here are your two bearings generally the bearing number will be on the outside if the person who put it together did a good job and you probably you can't see it on the camera sorry to tell you is 6 2 0 3 Z so that's the bearing number and you would use that to find an exact replacement because these guys come in standard sizes same for that one in order to get those off you're gonna need a bearing puller here we have a bearing puller and the basic idea is that these jaws will grab the inside of the bearing this little point goes on the end of the shaft and almost all shafts have that little recess and a tip point goes in there and you would take a wrench and screw that guy down until they pull the bearing off because that fit is very tight now there are more details that I'm leaving out in regards to how to get the bearings off and stuff like that and that's because I've already made a whole video dedicated to this so I'll put a link in the description if your problem is replacing the bearings now when you're bearing begins to fill generally you have two symptoms one the motor gets noisy and here's it's kind of whining and making this or rattling sound the second symptom will be issues with torque it doesn't seem to be as strong as it used to be so almost anything can stop the motor up and that can often be because the bearing is failing so when the bearing itself is under load they can't spin like it's supposed to spin again I've got a video that shows you how to replace the bearings and I'll put a link in the description ok I've got another permanent magnet DC motor and you see it's got some blue wire sticking out of the side these wires are for thermal protection now not all motors have the thermal protection wired externally like this some of them are just wired inside so if you having a problem where the motor is getting really hot and then it shuts off then that's your thermal overload shutting off the motor only thing you can do to resolve that is wait for it to cool off you can put fans on it whatever you need to do but there's a tiny strip of metal in there that's expanding and shutting off the circuit and it's got to cool off to the right temperature in order for the motor to turn back on you do need to investigate why the motors overheating though very likely it's because the load is too high or the temperature the ambient temperature is too hot almost all motors have a temperature rating this one doesn't have one all right this guy ambient temperature 40 C so if you're in an environment where the temperature is above 40 degrees C and the motor may begin to overheat and this one also has thermal protection it says they're thermally protected said this motor will shut off if the thermal protection is triggered another thing you can do is wait and resolve the issue that's causing a motor to overheat one last thing I want to show you on this motor which I have cut open to make it easier to see the inside and that's this little trigger here in the back so here is a centrifugal switch and what I'm about to show you is not what I will consider to be a DIY level fix but hey it's pretty neat I wanted to show it to you what I'm pushing on is the trigger for the start winding so whenever the motor is disconnected like it is now these Springs keep that circuit closed so that guy makes contact with the start winding and that allows the motor to get moving now if that sounds foreign to you you'll have a video on single-phase induction motors and how they start and now I explain why you need to start winding and all that in that video but what I wanted to show you here is just this cool mechanism where when the motor starts spinning centrifugal force pushings pushes those weights out to the side and that disconnects the switch it's really neat this is the kind of stuff that makes me want to cut motors open and take a look at the inside see what the engineers came up with but anyway it's a cool mechanism for allowing the motor to start connected to the start winding and then disconnect it and that allows them to use thinner wire for the start winding so this I've got some loose wires here if you compare the start winding motors wires to the run windings you can see that's almost double the thickness this makes the motor a lot cheaper because you don't have to wind both the run whining and the start winding with heavy gauge wire when the start winding is only connected for not even a full second anyway I hope you found that interesting well I would love to know if you guys have any interesting motor problems that I didn't cover here because for the most part motors don't fail very often it's usually something in the circuit before the motor but if you've had an interesting motor failure and you figured out how to fix it I would love to know sort of like rewinding the motor we're not talking about those kind of high end fixes but I am curious if you've had any obscure strange fixes that were easy to repair leave that in the comments and I might even add something to the description about it if I find some that are really interesting and helpful this wraps up a three part series so if you haven't seen the other videos you can click on the link that pops up here and also if you want to see more content like this hit the subscribe button if I earned it and then you'll be notified whenever the next video comes out thanks for watching

Channel: Jeremy Fielding

Views: 560,821

Rating: 4.9592772 out of 5

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Id: uAhVfVvoK3M

Length: 14min 10sec (850 seconds)

Published: Mon May 13 2019