My air compressor was trying to start, turned over a couple of times then would trigger the overload breaker on the motor. I tried removing the start capacitor (150uF 250v) (which I thought was the culprit) and same symptom. The run capacitor (35uF 450V) was enough to start the compressor when there was no air in the tank, but under load - no dice. I bought a new start capacitor, installed it and now she starts without the slightest hesitation. Victory!!
I haven't studied or had anything to do with capacitors for 50 years. I still remember a lot of the schooling I had many years ago, but seeing this video refreshed a lot of my knowledge. Totally understand and appreciate the video.
AC capacitors are non-polarity specific, so it doesn't matter how you connect it on your replacement run cap. Internal failure on the capacitor is most likely what happened. Something probably shorted in the capacitor, which caused it to heat and boil the oil internally. As the heat rose, the increasing pressure caused it to explode.
So, there is an internal breaker on these motors? My motor powers up, and then (trips something), cuts power, then back to full power, then cuts power... continually.
I am new to this, but your video is very interesting. My question is, how do you know which cable from the electric motor goes where in the capacitor (I always do a trial an error to discover that) and I want to be precise on how to connect them ??
Good video I would suggest that you check that the capacitor is fully discharged before you touch the terminals because if the resistor is blown it may not be.
FYI ... called TEMCo to discuss issue. They said motor bad. Anyway since I've got time on my hands I decided to pursue investigating on my own. Turned out the points on my Bremas switch were bad and I switched them around and I'm back in business. Also, I repeated the capacitor circuit (capacitor removed) and it still checks open ... YET EVERYTHING IS FINE NOW AND OPERATING.
thank you very much I don't have just spent the last hour and a half trying to read the Bible of HVAC I'm glad you said what you said at the four and a half minute mark.
If it's a capacitor with only two terminals, the polarity does not matter. Just make sure that all the wires that are supposed to be on one terminal on the old capacitor are on one end of the new one, and same for the other terminal. If it has three terminals, they should be marked.
I always wondered what that hump on the side of the motor was for. Thanks for the great explanation. Like your other videos as well. Wish we could have seen these lessons when I was in school back in the 80's.
Thanks for the informative video. I changed the capacitor on my drill press and it worked. (Old one tested bad). However my capacitor almost looked new. Listened to you full video regarding how they fail and almost destroy themselves, ie: "Spill their gutts." Since it's so easy to do, I opened my band saw, table saw, two miter saws, and any other tool I had and logged the capacitor numbers. Much easier to find a replacement in case the numbers get destroyed. Thanks again. One note though? If it doesn't have a bleed down resister, how does one go about discharging one.
Capacitors may store a charge after removal. Simply short the terminals with an insulated screwdriver. If you see a spark the charge has been neutralized.
@@ellieprice3396 I did that once with a 465 mfd cap. Sounded like a .357 Mag going off in my face and burned a pit into the side of the screwdriver. From that point forward I hooked up a voltmeter and shorted with a resistor. That way I could watch the discharge as it happened and there was no excitement.
Nice video. I have a compressor that starts and runs but will not restart once air gets low. It will only restart after it’s been off for about 5 to 10 minutes. Could this be a bad start compactor or the switch that tells it to start ? Thanks.
Most start caps don't come with resistors. If your original start cap didn't come with a resistor, it is safe to assume you don't need one. It never hurts to put one on, though!
The smoke comes from the side of the motor. Didn't push the button long enough to see if it would trip any kind of safety switch. Just hit the button after it smoked to see if it would still work. It still works the same but heats up and smokes after about 2 or 3 seconds
Thank you for sharing the clip. Let me drop some questions. I have a single phase induction motor. 4 poles, 2HP, 1.5kw, 220Vac, 1700rpm. It has A capacitor which is 600uf in 110Vac. but the motor runs in 220Vac. I thought the capacitor should be more than 220Vac. I don't get it how come the capacitor is 110Vac. do you think it is able to replace the capacitor which is 100uf in 250Vac? what is the fatal part and value to enhance the torque of the motor? if it has changed what would happen in the motor?
No, the capacitance is generally matched to the start winding in the motor. Going with a lower value may cause the motor to not start at all, in our experience.
I have a 1/2Hp 115v motor which has 1 62mfd capacitor with 4 wires connected to it. Having a heck of a time finding a replacement capacitor for it. Thought about using a 60 /5 mfd capacitor in series.
Thanx for the vid, I'm great on automotive DC applications but AC is different, My shop compressor just went down and this was just the info I needed to help get started diagnosing before I start shoveling $$ at it.
Thanks so much for doing this tutorial. It helped narrow out the problem and going over the functions of the tester was really helpful with the measurement units. I will test the switch and capacitor on the bench grinder I'm trying to save. It's not so much I can't afford to get another one, but this one has some history, and it really worked good before it just died.... Again thanks for making the video, I'm going to check out your others...subscribed!!!!!!
Really good explanation. I received a replacement motor "Delta Band saw Model #28-245 1/2 HP 62-142 motor" and needed to reverse the rotation. I can't find an explanation and did it wrong. The motor still runs but I have to spin the saw by hand. I suspect from the smoke that I fried the capacitor. Can you help me with the right replacement part and a "How to" on reversing the spin?
Thanks, this answered the questions I had about determining whether the start capacitor is at fault on my table saw motor. Would it make sense to also change out the run capacitor when replacing the start capacitor or is the wear unrelated?
Hi, I like the video, My problem though is I didn't take off the old burnt out capacitor so I don't know which wire goes to which connection. Is there an easy way to determine which is which ? Thanks Phil.
Thanks you for the video. I have a ridgid table saw. The motor trying to turn. I check the capacitor same as you did check my fluke multimeter. The capacitor it read "OL" it seems short to me. I need your feedback. The Capacitor made by CD60 MOTOR STARTER 200 micro Farad 250VAC -40/ +65b50/60 HZ E357070 Regards Manny
I ordered capicators from you guys. The 216-259Uf 250vac 60hz The capicators are much smaller in size with the same specs. Will this work? Will it not work for long? Why are they smaller with the same numbers? Thank u
Hi - very useful and informative video, thank you. My motor is connected to a planer / thicknesser. There are two switches, one to use the planer and one for the thicknesser, when I select the planer, the motor runs fine, when I select the thicknesser, there is a sound similar to a trip switch clicking off and there is a low humming sound from the motor. From other forums relating to the machine in question it has been suggested that there maybe an issue with the start capacitor, so my question is, could this be possible? My feeling is that it won't be as the motor starts fine in planer mode. If I am wrong about that, do you have any suggestions please?
What should I do if I have a motor that I scrapped that is just missing the start capacitor from the get-go? Is there any way to determine what farrad rating a new capacitor should be just based on the voltage/amperage ratings on the motor itself?
i left a comment on your video explaining about my motor. My motor does hum and it is an old motor. If i leave it plugged in for says 5 seconds it blows the fuse on my plug. Any ideas whether it is the switch or the capacitor?
what if the start capacitor is bigger than the one you want to replace? For example I have a 160 uF and I want to put a 400 uF capacitor. Will that affect anything in a bad way?
I have two questions if you please: 1- Do I need to remove the resistor when measuring the capacitance, or can I leave it on? I've seen a couple of youtube vids where the resistor was disconnected at one terminal before testing the capacitance. 2- when I buy a replacement start capacitor with an MFD range, ideally, should the capacitance be in the middle of the range? What if it is very close to the lower end of the range? Should I get another one?
I purchased an air conditioner hard start kit. I want to check the start capacitor before installing. The capacitor has a resistor, but I prefer not to remove the resistor in case I need to return the start kit in case it is bad. What happens if I test the capacitor with the resistor? Most RUclips videos, like you, say to remove the resistor. Yet, there are two videos that test with the resistor with one testing in range and the other testing considerably over range. (I tried to test yesterday with my cheap volt ohm meter, but the capacitor is about 300 mfd and my meter only goes to 100 mfd.)
Very nice video and very informative. Could you please advise what could be the issue on a porter cable table saw motor that runs without the blade but not with the blade on?
Good video and explanation, thanks. Went to your website to find a start capacitor for a typical floor fan. The info on my old capacitor is 3.0 uF and 250VAC. Didn't see anything like that on your website. Maybe too small for your company to handle. A few questions please: 1. Any suggestions for replacement source? 2. Saw no resistor. The capacitor is a small square plastic unit with no external parts. Do capacitors this size typically have no resistors? 3. The wires from the motor to the capacitor also have no quick-release connections at the capacitor. Are those designed to be removed from within the motor itself or do I just use wire cutters to cut it free as near to the old capacitor as possible? Thanks for any info.
Thanks for the input. Steve: You will need a 160 - 200 mfd, 275V start capacitor. We don't carry that particular spec, but you should be able to find plenty online (like eBay).
Please clarify motor symptoms when centrifugal switch is stuck closed. Does the motor fail to turn and emit a grinding and humming sound - or does it run with that sound? My situation: Washing machine motor, taken loose from the machine but still on wire harness. Hums but doesn't turn. If I turn the shaft manually, it makes a few slow rotations and stops. Start capacitor looks good and measured capacitance is within spec. No bleed resistor across capacitor terminals - probably somewhere else within the washer.
The resistor is such a small part of the circuit for the brief time that the start cap is engaged that it will not affect the motor in any way. The start cap, and therefore the resistor, are taken out of the circuit as soon as the motor is up to speed. As for sizing, you'd want a resistor that matches the voltage of the cap. Since they're not part of the circuit, resistors don't have any affect on the motor's performance. It is really only used for safety reasons as mentioned in the video.
Does it matter which wire goes on which terminal of the capacitor? On my Mallory 400-480MFD, one terminal has a copper colored dot, the other is plain metal.
I have a 20 yr old Jet table saw that has started to bog on start up. Once up to speed, which only takes a couple seconds, the saw runs fine. Is the start capacitor on the way out? Do they fail slowly, or just quit? Thanks, Ocotillodavid
tanks for the vidio,what cause the start capasitor to bwow several times but not runing capasitor,and how will i know the spesifick start capasitor of 220-250vac/32.5A
I have a small table top drill press that i may have ran a bit to hard....I know the motor was hot when i was finished....no smoke no sparks etc. Now it will start but only runs on slow speed. I have the start capacitor and cannot get a reading other than 0L continuity it measure 1.16 ohms I wonder if the motor would even start if the cap is bad? The capacitor is 16mF 250 Volts Thanks for the videos !!!
Hello mate, very helpful video. In England we have a brand of light industrial single phase ‘clarke’ air compressors. It’s blows a fuse on start up. I’m suspecting the capacitor. Does it matter which brand capacitor I use as long as it’s the same digits? 450v 80uf.
I purchased a used Hilka bench grinder,To get it running I have to spin the wheel, The capacitor reads 5uF + - 5% wv 370 W ,AC The grinder is 240 v single phase,50.60 HZ ! 1/2 HP, I don’t know if it’s the original Cap! Also in your vids most caps have a resistor across the capacitor,mine doesn’t,should I fit one.With details given could you work out what size cap I should purchase,It has two wires to the cap ,the other end of the cap has a stud for a nut fixing ,length approximately 2 1/2 inches Dia 1 1/2 inches metal case.Any advice would be most welcome,I’ve had no response. From manufacturers,Thankyou.
Thank you very much for valuable knowledge you shared about changing capacitor, please can you help me about this. My induction motor has two capacitor 1. is 30 micro farad and has 250/400V and and the other one is 150 micro farad and 250/400v; so I only have new ones to replace but it is 30 micro farad 400v and the other one is 200 micro farad 250v. is there any adverse effect if i will use this? this only available in the market in my small town here in Hinigaran Negros Occidental Philippines. thanks
@Demo Niq Over capacitance, just like too little capacitance, could cause your motor to not start due to improper phase delay. You always want to target as close as possible to the original capacitor's mfd rating.
Hi, Just replaced a 64 MFD 330 v with another 64-77 MFD 330v START-UP CAP, this one after 3-5 minutes of starting an old fridge blow up almost too with fumes. What would you advice go for a higher ratings of 180 MFD 430-450 VOLTS? Are they suppose to be left free for movement and vibration or tied up to stop it from vibration?, as our fridge makes lots of noise and makes a big contact noise at start up.
At my job we had 48” fans and sometimes when we turned on a fan I noticed the fan would start up very slow. I would check and change out the capacitor and then the fan would start normally again.
Is the smoke coming from the motor or the controls? Does it trip the overcurrent protection? This info might help us narrow down where the problem is occurring. Feel free to call us for help on your application as well (number available in video description).
I HAVE AN OLD RADIAL ARM SAW WITH A START CAPACITOR (200-240) THAT I HAVE TESTED TO BE BAD, BUT IT DOES NOT HAVE A RESISTOR AS PER YOUR VIDEO. DO I NEED TO ADD ONE? IF SO HOW DO I KNOW WHICH ONE TO BUY? OR IS IT OK TO JUST KEEP IT AS ORIGINAL
Not sure if there was a bleed-off resistor on my original cap. because it's missing. Is there any harm in including a resistor if on the original there may have been none?
I have a older drill press that when I turn it on it just buzzes. If i give the belt a pull it will start up. In the video you mentioned a speed switch do you have a video on fixing this?
We don't have a video on fixing the speed switch. It is more likely a problem with the start cap though, so try replacing the cap or verify its mfd value.
If you have a 25 uf capacitor? And it measures 30 uf? Is that acceptable Most people referred to bad caps having too low uf, if it's too high? Is it ok?
I have a Balder bench grinder it will start but when I grind a peice of metal it bogs way down.. It use to grind and now it doesn't like it use to I was wondering if it might be the capacitor I did take it apart and on the bottom there is a capacitor..and it looks like a Air-conditioner capacitor. Any help would be appreciated thanks..
Thank you for sharing your knowledge. I'm still a bit green when it comes to AC applications, and was wonder if maybe you could help. I salvaged a (115v-4A Haier 0034000074) motor from a Whirlpool washing machine a few months ago to use in a homemade lathe, and put a plug-end on it. The motor wont start on it's own but will run after turning by hand, but I don't recall seeing a capacitor in the washing machine (but could have missed it). My first thought was that it needed a capacitor (and redirected here from your other video on capacitors.), but it seems like this type of motor wouldn't need a capacitor. Any help would be greatly appreciated, thanks in advanced.
I have an old ingersol rand air compressor with a 2 hp motor. the past year when I threw the on switch, sometimes it would start right up other times it would hum. today I tried to use it and it just hummed and ultimately the floor surge protector it was plugged into tripped. I removed the cover and I could see ( when I reset the switch) a very slow turn of the crank rod but with in about one full revolution it would trip the cirquit again. the motor looks like the one you have says 8-175661-22 and fr y56y and 170501 on the metal plate. it has the two humps on the bottom where the capacitors are mounted. so my question is which one is the start capacitor? and you also mentioned if the motor hummed it could be a bad start switch? How would I know that the problem is the start switch and not the start capacitor.?
I have a Westinghouse single phase motor on my bandsaw that stopped working, 3/4 hp.,Type FZ, Rpm 1725, Volt 115 , A 11.0, HZ 60 , Thermally protected reset button, HSG open, Type M, Code H, INS B, Serial #E317P219 unfortunately on Westinghouse website their documents only goes up to #E317P079. It only has a Start capacitor on it upon investigation has oozed a tar like material out of it and has distorted if not erased the key numbers I need to replace it. And Westinghouse manuals won't give you any information on the capacitors used other than Type FZ. So my question to you is which start capacitor would I need and what resistor would be needed as well seeing how mine didn't have one on it? Your help would be greatly appreciated!
I need to replace the capacitor on my drill press motor. It is an old Doerr motor and the capacitor is enclosed in a metal case , spot soldered to the attachment bracket to the motor. Would it come out of the case with information needed to get a replacement
Hello, I have an older Kollmann sewer snake which has a 3/4 ho single phase motor. This motor is revers able and worked in both directions. I recently had taken it apart to clean and service the clutch. I did nothing to the motor except lower off the cradle. Reassembled everything and unfortunately now the the motor only spins in reverse but not forward? Starts right up as it did prior but switched forward and nothing, no noise, etc. do you think my capacitor is bad? Don't see any loose connections, any help greatly appreciated, thanks, eric
I have a very old pump that has been replaced and thrown aside and I got to it and it's from the 1950's and I inspected it and the centrifical switch had been broken so I replaced it from another pump and then I didn't really know what the old capacitor was so I just grabbed one from another motor and put it on just to see if it would try to start as it did but when I tried to pump some water it was running and the capacitor blew up so do you think there is something wrong with the motor? To make the cap blow up...?
Does the motor actually get hot? If so, the thermal switch may be going out. Also check what amperage the motor is drawing when it does spin up and see if it is more than the nameplate recommends.
Hi great video but im having problems with my air compressor motor it does run when tank is empty and fill it up but when is time to kick back again it does run like for 30 sec and the thermal switch trips I did check both start and run cap and they liked good and their readings too hope u can help me out thx
I watched your previous video, thanks great info. after watching the 1st I went to the TEtemco online store and purchased a run capacitor. After watching this video: I think I need a Start capacitor. How can I tell the difference. it is coming off a RV roof AC. capacitor is rated 21-25 uf 165 VAC. The one I purchased on TEtemco is 25 uf 370 VAC. From watching previous it seems a running one usually has lower UF or MFD like mine. But don't have a little thingny in between the hook ups(the thing you took off and put on the new one) My old capacitor has one of those. So what do I have? run or start? can I just buy the little "thingny" and add to my capacitor even if it si a running one? PS: I waited on the phone forever for help, twice. I gave my number for a call back but I have not heard. this approx 1 hour ago. I also wanted to know what the other 3 tubular box next to my capacitor are? perhaps i need new one of those also? thank you much for this & previous video.... AWESOME
Great video. Thanks. I have a 1/12hp AC 227v motor that I want to run on 208v. I found it in a "bargain bin" in a hardware store. The capacitor was missing. I imagine I will need a 300v capacitor but I am not sure what capacitance i require and what resistor I need. How does one go about determining this?
Hey, I suspect my start cap has died on my tablesaw... bought a replacement today but ... the rating is the same 35u, and 450V, however it doesn;t have a mounting pole and also has 4 contacts instead of the two that my original has... I can use a zip tie to secure it instead of the pole mount with the M8 nut, but how do i figure out what to do with the 4 contacts instead of two ? Many thanks - Guy
What if you put the wires on backwards. I E what if I didnt mark the wires before I took them off....oops I have 2 hookup with 4 heads clips 30uf 440v for pool pump.. Thanks Great video
Hi. Thanks for the info video. I just acquired an 1950s Craftsman lathe with a 1/2 hp motor that has a flat capacitor in the base. The capacitor is bulged and leaking so I need to replace it. The problem is that there are no longer any readable markings on the capacitor. I have room for a round capacitor if I can just figure out which one. The motor is 110-120 V. 8.2 amps. Type CR220K21 D4 50 Model # 1156962 and made by King Seeley. for Sears Craftsman. Thanks
You generally need some fairly fancy engineering data from the original design of the motor that's not available to the public to size a capacitor for a motor. Outside of this, the next best technique would be trial and error. One rule of thumb is approx 80 uF per kilowatt of motor power and may be a good place to start.
Wouldn't the first thing to check is that the cap is discharged before touching it, check with meter or use a screw driver to short out both terminals to make sure it's discharged.
You mentioned that the switch is normally closed when not rotating. You measured across the capacitor terminals and had a dead short. Doesn't that take the capacitor out of the circuit (i.e. a dead short across the capacitor terminals)?
The measurement should've been across the leads coming from the centrifugal switch, and the motor windings wouldn't have been included in the measurement.
I have this 3ph 5hp 230VAC motor. Its 3 phases and I found a circuit on the web that describe a way to turn 1 phase power source and convert it for 3 phase motor. According to the author is needed two caps for continuously run the motor and also one big cap for the start. I experimented and found that it works quite well. My interrogation is concerning the Start aspect of the circuit. I learned from your other video what the difference is between Start and Run caps. I would then assume that in my application the big cap used to start the 3ph motor it would be sufficient to use the start cap for a period of 1 second in order to start the motor and then let the motor run on the two run cap. Question: Can I get some more specific data on your Start Capacitor like Max Peak Current and How many seconds can we use the Start Cap connected. We do not see those kind of details on the cap data sheet provided by TEMCo. I just want to make sure I will not use the start cap over its capability. thanks
2 spd pool pump motor that will no longer kick into high speed unless I start it on low speed. If it is started at low speed then I flip the 2 spd timer to high no problem, it runs but try to start from stopped to high it buzzes then the thermal overload kicks in and i have to wait for 20 minutes. Is this due to a weak start capacitor or problem with the centrifugal switch?
Hi,, I'm checking out a 125 vac motor for a neighbor s air compressor. His symptoms are, no hum, no start. Have power to switch but that's it. I checked the start cap which is 250uf 125vac cap. One meter reads 306 mf another reads ol. Strange. Does this more sound like the start switch,,or cap, in your opinion? Thanks much.
If a motor with a single start capacitor is rewired to run on 208v from 115v, does the start capacitor also need to be replaced with one with a higher voltage rating? Thanks.
If I have a capacitor that is bad and I have a replacement but the wires on the motor are both red and no markings so how do I determine which ones go to what terminals. This is on a Delta Bandsaw.
good day sir, i have a washing machine a normal one with spinner but the washer wont spin unless you need to use your hand to turn the thub then it will spin after that it stop again the use again your hand to do it and kind uh waste of time what do you think the problem is??i swap the connection on spinner and washer of the connection on the capacitor but still same problem would it be the motor problem ?? or the wiring ?? thanks..
With the power off, when you try to turn the motor shaft by hand, does it turn freely or is there some resistance? If there is some resistance, the bearings probably need replacement. If it spins freely, you probably want to look into a replacement capacitor.
My air compressor was trying to start, turned over a couple of times then would trigger the overload breaker on the motor. I tried removing the start capacitor (150uF 250v) (which I thought was the culprit) and same symptom. The run capacitor (35uF 450V) was enough to start the compressor when there was no air in the tank, but under load - no dice. I bought a new start capacitor, installed it and now she starts without the slightest hesitation. Victory!!
I haven't studied or had anything to do with capacitors for 50 years. I still remember a lot of the schooling I had
many years ago, but seeing this video refreshed a lot of my knowledge. Totally understand and appreciate the video.
Good smart video (no music). Will show this to apprentices doing motors. Cutting to the meter at the right time made it clear.
AC capacitors are non-polarity specific, so it doesn't matter how you connect it on your replacement run cap.
Internal failure on the capacitor is most likely what happened. Something probably shorted in the capacitor, which caused it to heat and boil the oil internally. As the heat rose, the increasing pressure caused it to explode.
So, there is an internal breaker on these motors? My motor powers up, and then (trips something), cuts power, then back to full power, then cuts power... continually.
I am new to this, but your video is very interesting. My question is, how do you know which cable from the electric motor goes where in the capacitor (I always do a trial an error to discover that) and I want to be precise on how to connect them ??
@Weaver Cattle Company Thank you
Good video
I would suggest that you check that the capacitor is fully discharged before you touch the terminals because if the resistor is blown it may not be.
FYI ... called TEMCo to discuss issue. They said motor bad. Anyway since I've got time on my hands I decided to pursue investigating on my own. Turned out the points on my Bremas switch were bad and I switched them around and I'm back in business. Also, I repeated the capacitor circuit (capacitor removed) and it still checks open ... YET EVERYTHING IS FINE NOW AND OPERATING.
Thank you, figured the bleed resistor was messing up my checks but wasn't sure if there was a trick to measure around it
thank you very much I don't have just spent the last hour and a half trying to read the Bible of HVAC I'm glad you said what you said at the four and a half minute mark.
If it's a capacitor with only two terminals, the polarity does not matter. Just make sure that all the wires that are supposed to be on one terminal on the old capacitor are on one end of the new one, and same for the other terminal.
If it has three terminals, they should be marked.
I always wondered what that hump on the side of the motor was for. Thanks for the great explanation. Like your other videos as well. Wish we could have seen these lessons when I was in school back in the 80's.
The two humps on the side of the motor means it is certain to be a female,if no humps on the side of the motor then it is definitely a male.
thanks for the very instructional vid .fixed my table saw motor,saved a fortune Cheers.
Scotty in OZ
Thanks for the informative video. I changed the capacitor on my drill press and it worked. (Old one tested bad). However my capacitor almost looked new. Listened to you full video regarding how they fail and almost destroy themselves, ie: "Spill their gutts." Since it's so easy to do, I opened my band saw, table saw, two miter saws, and any other tool I had and logged the capacitor numbers. Much easier to find a replacement in case the numbers get destroyed. Thanks again. One note though? If it doesn't have a bleed down resister, how does one go about discharging one.
Capacitors may store a charge after removal. Simply short the terminals with an insulated screwdriver. If you see a spark the charge has been neutralized.
@@ellieprice3396 I did that once with a 465 mfd cap. Sounded like a .357 Mag going off in my face and burned a pit into the side of the screwdriver. From that point forward I hooked up a voltmeter and shorted with a resistor. That way I could watch the discharge as it happened and there was no excitement.
Thanks a lot for posting this video. Now I'll go check my motor.
Thank you...very informative video. All the stuff you want to know without all the stuff you don't need to know.
Good tutorial. Not too fast or slow, no BS, nice job! Thanks
Nice video. I have a compressor that starts and runs but will not restart once air gets low. It will only restart after it’s been off for about 5 to 10 minutes. Could this be a bad start compactor or the switch that tells it to start ?
Thanks.
Most start caps don't come with resistors. If your original start cap didn't come with a resistor, it is safe to assume you don't need one. It never hurts to put one on, though!
The smoke comes from the side of the motor. Didn't push the button long enough to see if it would trip any kind of safety switch. Just hit the button after it smoked to see if it would still work. It still works the same but heats up and smokes after about 2 or 3 seconds
Thank you for sharing the clip.
Let me drop some questions.
I have a single phase induction motor. 4 poles, 2HP, 1.5kw, 220Vac, 1700rpm.
It has A capacitor which is 600uf in 110Vac.
but the motor runs in 220Vac.
I thought the capacitor should be more than 220Vac.
I don't get it how come the capacitor is 110Vac.
do you think it is able to replace the capacitor which is 100uf in 250Vac?
what is the fatal part and value to enhance the torque of the motor?
if it has changed what would happen in the motor?
No, the capacitance is generally matched to the start winding in the motor. Going with a lower value may cause the motor to not start at all, in our experience.
I have a 1/2Hp 115v motor which has 1 62mfd capacitor with 4 wires connected to it. Having a heck of a time finding a replacement capacitor for it. Thought about using a 60 /5 mfd capacitor in series.
Thanx for the vid, I'm great on automotive DC applications but AC is different, My shop compressor just went down and this was just the info I needed to help get started diagnosing before I start shoveling $$ at it.
Thanks so much for doing this tutorial. It helped narrow out the problem and going over the functions of the tester was really helpful with the measurement units. I will test the switch and capacitor on the bench grinder I'm trying to save. It's not so much I can't afford to get another one, but this one has some history, and it really worked good before it just died.... Again thanks for making the video, I'm going to check out your others...subscribed!!!!!!
Great Video, I am just learning about these in my school work. Very good explanation. Thanks
Really good explanation. I received a replacement motor "Delta Band saw Model #28-245 1/2 HP 62-142 motor" and needed to reverse the rotation. I can't find an explanation and did it wrong. The motor still runs but I have to spin the saw by hand. I suspect from the smoke that I fried the capacitor. Can you help me with the right replacement part and a "How to" on reversing the spin?
Thanks, this answered the questions I had about determining whether the start capacitor is at fault on my table saw motor. Would it make sense to also change out the run capacitor when replacing the start capacitor or is the wear unrelated?
Hi, I like the video, My problem though is I didn't take off the old burnt out capacitor so I don't know which wire goes to which connection. Is there an easy way to determine which is which ? Thanks Phil.
Thanks you for the video. I have a ridgid table saw. The motor trying to turn. I check the capacitor same as you did check my fluke multimeter. The capacitor it read "OL" it seems short to me. I need your feedback. The Capacitor made by CD60 MOTOR STARTER 200 micro Farad 250VAC -40/ +65b50/60 HZ E357070 Regards Manny
If you are using the capacitance setting on your meter, the capacitor is probably bad. Good luck!
I ordered capicators from you guys.
The 216-259Uf 250vac 60hz
The capicators are much smaller in size with the same specs. Will this work? Will it not work for long? Why are they smaller with the same numbers? Thank u
Hi - very useful and informative video, thank you. My motor is connected to a planer / thicknesser. There are two switches, one to use the planer and one for the thicknesser, when I select the planer, the motor runs fine, when I select the thicknesser, there is a sound similar to a trip switch clicking off and there is a low humming sound from the motor. From other forums relating to the machine in question it has been suggested that there maybe an issue with the start capacitor, so my question is, could this be possible? My feeling is that it won't be as the motor starts fine in planer mode. If I am wrong about that, do you have any suggestions please?
What should I do if I have a motor that I scrapped that is just missing the start capacitor from the get-go? Is there any way to determine what farrad rating a new capacitor should be just based on the voltage/amperage ratings on the motor itself?
i left a comment on your video explaining about my motor. My motor does hum and it is an old motor. If i leave it plugged in for says 5 seconds it blows the fuse on my plug. Any ideas whether it is the switch or the capacitor?
what if the start capacitor is bigger than the one you want to replace? For example I have a 160 uF and I want to put a 400 uF capacitor. Will that affect anything in a bad way?
Thanks for all the help..... Off to get a motor :)
I have two questions if you please:
1- Do I need to remove the resistor when measuring the capacitance, or can I leave it on? I've seen a couple of youtube vids where the resistor was disconnected at one terminal before testing the capacitance.
2- when I buy a replacement start capacitor with an MFD range, ideally, should the capacitance be in the middle of the range? What if it is very close to the lower end of the range? Should I get another one?
I purchased an air conditioner hard start kit. I want to check the start capacitor before installing. The capacitor has a resistor, but I prefer not to remove the resistor in case I need to return the start kit in case it is bad. What happens if I test the capacitor with the resistor? Most RUclips videos, like you, say to remove the resistor. Yet, there are two videos that test with the resistor with one testing in range and the other testing considerably over range. (I tried to test yesterday with my cheap volt ohm meter, but the capacitor is about 300 mfd and my meter only goes to 100 mfd.)
Great video! Well put together. All usable content and no fluff.
Very nice video and very informative. Could you please advise what could be the issue on a porter cable table saw motor that runs without the blade but not with the blade on?
Good video and explanation, thanks. Went to your website to find a start capacitor for a typical floor fan. The info on my old capacitor is 3.0 uF and 250VAC. Didn't see anything like that on your website. Maybe too small for your company to handle. A few questions please:
1. Any suggestions for replacement source?
2. Saw no resistor. The capacitor is a small square plastic unit with no external parts. Do capacitors this size typically have no resistors?
3. The wires from the motor to the capacitor also have no quick-release connections at the capacitor. Are those designed to be removed from within the motor itself or do I just use wire cutters to cut it free as near to the old capacitor as possible?
Thanks for any info.
Thanks for the input.
Steve: You will need a 160 - 200 mfd, 275V start capacitor. We don't carry that particular spec, but you should be able to find plenty online (like eBay).
Please clarify motor symptoms when centrifugal switch is stuck closed. Does the motor fail to turn and emit a grinding and humming sound - or does it run with that sound?
My situation: Washing machine motor, taken loose from the machine but still on wire harness. Hums but doesn't turn. If I turn the shaft manually, it makes a few slow rotations and stops. Start capacitor looks good and measured capacitance is within spec. No bleed resistor across capacitor terminals - probably somewhere else within the washer.
Good explanation of start capacitor test. *****
The resistor is such a small part of the circuit for the brief time that the start cap is engaged that it will not affect the motor in any way. The start cap, and therefore the resistor, are taken out of the circuit as soon as the motor is up to speed. As for sizing, you'd want a resistor that matches the voltage of the cap.
Since they're not part of the circuit, resistors don't have any affect on the motor's performance. It is really only used for safety reasons as mentioned in the video.
Does it matter which wire goes on which terminal of the capacitor? On my Mallory 400-480MFD, one terminal has a copper colored dot, the other is plain metal.
AC capacitors are non-polarized, so it doesn't matter which wire goes on which terminal.
Thanks!
very informative vid. Great breakdown on capacitors, no engineer speak.
I have a 20 yr old Jet table saw that has started to bog on start up. Once up to speed, which only takes a couple seconds, the saw runs fine. Is the start capacitor on the way out? Do they fail slowly, or just quit?
Thanks,
Ocotillodavid
tanks for the vidio,what cause the start capasitor to bwow several times but not runing capasitor,and how will i know the spesifick start capasitor of 220-250vac/32.5A
I have a small table top drill press that i may have ran a bit to hard....I know the motor was hot when i was finished....no smoke no sparks etc. Now it will start but only runs on slow speed. I have the start capacitor and cannot get a reading other than 0L continuity it measure 1.16 ohms I wonder if the motor would even start if the cap is bad? The capacitor is 16mF 250 Volts Thanks for the videos !!!
Hello mate, very helpful video. In England we have a brand of light industrial single phase ‘clarke’ air compressors. It’s blows a fuse on start up. I’m suspecting the capacitor. Does it matter which brand capacitor I use as long as it’s the same digits? 450v 80uf.
I need to check the capacitor for a Ryobi table saw. Would the process be the same!Thanks, David
I purchased a used Hilka bench grinder,To get it running I have to spin the wheel, The capacitor reads 5uF + - 5% wv 370 W ,AC The grinder is 240 v single phase,50.60 HZ ! 1/2 HP, I don’t know if it’s the original Cap! Also in your vids most caps have a resistor across the capacitor,mine doesn’t,should I fit one.With details given could you work out what size cap I should purchase,It has two wires to the cap ,the other end of the cap has a stud for a nut fixing ,length approximately 2 1/2 inches Dia 1 1/2 inches metal case.Any advice would be most welcome,I’ve had no response. From manufacturers,Thankyou.
Hello Chris, if you need replacement capacitors, we carry them on our website. See the description box for the link.
Thank you very much for valuable knowledge you shared about changing capacitor, please can you help me about this. My induction motor has two capacitor 1. is 30 micro farad and has 250/400V and and the other one is 150 micro farad and 250/400v; so I only have new ones to replace but it is 30 micro farad 400v and the other one is 200 micro farad 250v. is there any adverse effect if i will use this? this only available in the market in my small town here in Hinigaran Negros Occidental Philippines. thanks
@Demo Niq Over capacitance, just like too little capacitance, could cause your motor to not start due to improper phase delay. You always want to target as close as possible to the original capacitor's mfd rating.
TEMCo Industrial
The new capacitor needs to be installed with or without a charge?
Hi, Just replaced a 64 MFD 330 v with another 64-77 MFD 330v START-UP CAP, this one after 3-5 minutes of starting an old fridge blow up almost too with fumes. What would you advice go for a higher ratings of 180 MFD 430-450 VOLTS?
Are they suppose to be left free for movement and vibration or tied up to stop it from vibration?, as our fridge makes lots of noise and makes a big contact noise at start up.
Would like to get the right parts I need from you guys if I can find out what's wrong with it.
At my job we had 48” fans and sometimes when we turned on a fan I noticed the fan would start up very slow. I would check and change out the capacitor and then the fan would start normally again.
Is the smoke coming from the motor or the controls? Does it trip the overcurrent protection? This info might help us narrow down where the problem is occurring. Feel free to call us for help on your application as well (number available in video description).
I HAVE AN OLD RADIAL ARM SAW WITH A START CAPACITOR (200-240) THAT I HAVE TESTED TO BE BAD, BUT IT DOES NOT HAVE A RESISTOR AS PER YOUR VIDEO. DO I NEED TO ADD ONE? IF SO HOW DO I KNOW WHICH ONE TO BUY? OR IS IT OK TO JUST KEEP IT AS ORIGINAL
Not sure if there was a bleed-off resistor on my original cap. because it's missing. Is there any harm in including a resistor if on the original there may have been none?
Great video good job
I have a older drill press that when I turn it on it just buzzes. If i give the belt a pull it will start up. In the video you mentioned a speed switch do you have a video on fixing this?
We don't have a video on fixing the speed switch. It is more likely a problem with the start cap though, so try replacing the cap or verify its mfd value.
Ok I'll try that and let y poo u know thanks for the great videos too
If you have a 25 uf capacitor? And it measures 30 uf? Is that acceptable
Most people referred to bad caps having too low uf, if it's too high? Is it ok?
I have a Balder bench grinder it will start but when I grind a peice of metal it bogs way down.. It use to grind and now it doesn't like it use to I was wondering if it might be the capacitor I did take it apart and on the bottom there is a capacitor..and it looks like a Air-conditioner capacitor. Any help would be appreciated thanks..
Thank you for sharing your knowledge. I'm still a bit green when it comes to AC applications, and was wonder if maybe you could help. I salvaged a (115v-4A Haier 0034000074) motor from a Whirlpool washing machine a few months ago to use in a homemade lathe, and put a plug-end on it. The motor wont start on it's own but will run after turning by hand, but I don't recall seeing a capacitor in the washing machine (but could have missed it). My first thought was that it needed a capacitor (and redirected here from your other video on capacitors.), but it seems like this type of motor wouldn't need a capacitor. Any help would be greatly appreciated, thanks in advanced.
The closest motor I've found is the replacement motor ( W10416664 ).
I have an old ingersol rand air compressor with a 2 hp motor. the past year when I threw the on switch, sometimes it would start right up other times it would hum. today I tried to use it and it just hummed and ultimately the floor surge protector it was plugged into tripped. I removed the cover and I could see ( when I reset the switch) a very slow turn of the crank rod but with in about one full revolution it would trip the cirquit again. the motor looks like the one you have says 8-175661-22 and fr y56y and 170501 on the metal plate. it has the two humps on the bottom where the capacitors are mounted. so my question is which one is the start capacitor? and you also mentioned if the motor hummed it could be a bad start switch? How would I know that the problem is the start switch and not the start capacitor.?
I have a Westinghouse single phase motor on my bandsaw that stopped working, 3/4 hp.,Type FZ, Rpm 1725, Volt 115 , A 11.0, HZ 60 , Thermally protected reset button, HSG open, Type M, Code H, INS B, Serial #E317P219 unfortunately on Westinghouse website their documents only goes up to #E317P079. It only has a Start capacitor on it upon investigation has oozed a tar like material out of it and has distorted if not erased the key numbers I need to replace it. And Westinghouse manuals won't give you any information on the capacitors used other than Type FZ. So my question to you is which start capacitor would I need and what resistor would be needed as well seeing how mine didn't have one on it? Your help would be greatly appreciated!
I need to replace the capacitor on my drill press motor. It is an old Doerr motor and the capacitor is enclosed in a metal case , spot soldered to the attachment bracket to the motor. Would it come out of the case with information needed to get a replacement
Hello, I have an older Kollmann sewer snake which has a 3/4 ho single phase motor. This motor is revers able and worked in both directions. I recently had taken it apart to clean and service the clutch. I did nothing to the motor except lower off the cradle. Reassembled everything and unfortunately now the the motor only spins in reverse but not forward? Starts right up as it did prior but switched forward and nothing, no noise, etc. do you think my capacitor is bad? Don't see any loose connections, any help greatly appreciated, thanks, eric
I have a very old pump that has been replaced and thrown aside and I got to it and it's from the 1950's and I inspected it and the centrifical switch had been broken so I replaced it from another pump and then I didn't really know what the old capacitor was so I just grabbed one from another motor and put it on just to see if it would try to start as it did but when I tried to pump some water it was running and the capacitor blew up so do you think there is something wrong with the motor? To make the cap blow up...?
very educational. Thanks
does it make any difference if you get the two wires mixed up on the start capacitor?
very useful video, thanks lot
Thanks! Another great video with tons of great Info!
Does the motor actually get hot? If so, the thermal switch may be going out. Also check what amperage the motor is drawing when it does spin up and see if it is more than the nameplate recommends.
Hi great video but im having problems with my air compressor motor it does run when tank is empty and fill it up but when is time to kick back again it does run like for 30 sec and the thermal switch trips I did check both start and run cap and they liked good and their readings too hope u can help me out thx
I watched your previous video, thanks great info. after watching the 1st I went to the TEtemco online store and purchased a run capacitor.
After watching this video: I think I need a Start capacitor.
How can I tell the difference. it is coming off a RV roof AC. capacitor is rated 21-25 uf 165 VAC.
The one I purchased on TEtemco is 25 uf 370 VAC.
From watching previous it seems a running one usually has lower UF or MFD like mine.
But don't have a little thingny in between the hook ups(the thing you took off and put on the new one)
My old capacitor has one of those.
So what do I have? run or start?
can I just buy the little "thingny" and add to my capacitor even if it si a running one?
PS: I waited on the phone forever for help, twice. I gave my number for a call back but I have not heard. this approx 1 hour ago.
I also wanted to know what the other 3 tubular box next to my capacitor are? perhaps i need new one of those also?
thank you much for this & previous video.... AWESOME
gcNewd Also: my old one is black just like the start capacitor... I am a bit confused now
Great video. Thanks. I have a 1/12hp AC 227v motor that I want to run on 208v. I found it in a "bargain bin" in a hardware store. The capacitor was missing. I imagine I will need a 300v capacitor but I am not sure what capacitance i require and what resistor I need. How does one go about determining this?
Best bet would be to contact the manufacturer or look on forums for similar motors for a value to start with, since it varies greatly.
So size of case doesn't matter? I believe that's what you said unless the case won't allow it. Right?
Hey, I suspect my start cap has died on my tablesaw... bought a replacement today but ... the rating is the same 35u, and 450V, however it doesn;t have a mounting pole and also has 4 contacts instead of the two that my original has... I can use a zip tie to secure it instead of the pole mount with the M8 nut, but how do i figure out what to do with the 4 contacts instead of two ? Many thanks - Guy
What if you put the wires on backwards. I E what if I didnt mark the wires before I took them off....oops I have 2 hookup with 4 heads clips 30uf 440v for pool pump.. Thanks Great video
Hi. Thanks for the info video. I just acquired an 1950s Craftsman lathe with a 1/2 hp motor that has a flat capacitor in the base. The capacitor is bulged and leaking so I need to replace it. The problem is that there are no longer any readable markings on the capacitor. I have room for a round capacitor if I can just figure out which one. The motor is 110-120 V. 8.2 amps. Type CR220K21 D4 50 Model # 1156962 and made by King Seeley. for Sears Craftsman. Thanks
You generally need some fairly fancy engineering data from the original design of the motor that's not available to the public to size a capacitor for a motor. Outside of this, the next best technique would be trial and error. One rule of thumb is approx 80 uF per kilowatt of motor power and may be a good place to start.
Very useful video, but I really wished you had explained how to identify the start capacitor from the run capacitor.
Wouldn't the first thing to check is that the cap is discharged before touching it, check with meter or use a screw driver to short out both terminals to make sure it's discharged.
When replacing the capacitor, does the resistor have to be reconnected to the same terminals or does it matter as in a diode?
Thanks
Rob
You mentioned that the switch is normally closed when not rotating. You measured across the capacitor terminals and had a dead short. Doesn't that take the capacitor out of the circuit (i.e. a dead short across the capacitor terminals)?
If you are reading through the motor windings shouldn't there be some resistance?
The measurement should've been across the leads coming from the centrifugal switch, and the motor windings wouldn't have been included in the measurement.
I have this 3ph 5hp 230VAC motor. Its 3 phases and I found a circuit on the web that describe a way to turn 1 phase power source and convert it for 3 phase motor. According to the author is needed two caps for continuously run the motor and also one big cap for the start. I experimented and found that it works quite well. My interrogation is concerning the Start aspect of the circuit. I learned from your other video what the difference is between Start and Run caps. I would then assume that in my application the big cap used to start the 3ph motor it would be sufficient to use the start cap for a period of 1 second in order to start the motor and then let the motor run on the two run cap. Question: Can I get some more specific data on your Start Capacitor like Max Peak Current and How many seconds can we use the Start Cap connected. We do not see those kind of details on the cap data sheet provided by TEMCo. I just want to make sure I will not use the start cap over its capability. thanks
I will have another look but i did say 275 VRMS. Im not sure what it means though. I will see if i can find any thing else on the capacitor. Thanks
I have liked this video.Can i replace a 10uf 400vAC with a 7.5uf 800vAC capacitor?
from what i understand there should be no more than 10 percent difference between the rated ufs.
Does it matter which wire goes to which lead on the capacitor? Do they work either way or is there polarity to worry about?
does not matter.
@@TEMCoIndustrial Yeah my brain kicked in later! Thanks.
Very informative thanks for the refresher course. Great Job
How about wire color not same with previous kapasitor? Any problem? How to fit back the wire?
This is what I was looking for 🤣
2 spd pool pump motor that will no longer kick into high speed unless I start it on low speed. If it is started at low speed then I flip the 2 spd timer to high no problem, it runs but try to start from stopped to high it buzzes then the thermal overload kicks in and i have to wait for 20 minutes. Is this due to a weak start capacitor or problem with the centrifugal switch?
Hi,, I'm checking out a 125 vac motor for a neighbor s air compressor. His symptoms are, no hum, no start. Have power to switch but that's it. I checked the start cap which is 250uf 125vac cap. One meter reads 306 mf another reads ol. Strange. Does this more sound like the start switch,,or cap, in your opinion? Thanks much.
If a motor with a single start capacitor is rewired to run on 208v from 115v, does the start capacitor also need to be replaced with one with a higher voltage rating? Thanks.
If I have a capacitor that is bad and I have a replacement but the wires on the motor are both red and no markings so how do I determine which ones go to what terminals. This is on a Delta Bandsaw.
good day sir, i have a washing machine a normal one with spinner but the washer wont spin unless you need to use your hand to turn the thub then it will spin after that it stop again the use again your hand to do it and kind uh waste of time what do you think the problem is??i swap the connection on spinner and washer of the connection on the capacitor but still same problem would it be the motor problem ?? or the wiring
??
thanks..
With the power off, when you try to turn the motor shaft by hand, does it turn freely or is there some resistance?
If there is some resistance, the bearings probably need replacement. If it spins freely, you probably want to look into a replacement capacitor.