Do not EVER put 120VAC across a capacitor !

Grew up in My Dads electric motor repair shop. we stripped out old motors and re used most parts back in the 1970s. one of my jobs was to charge each capacitor with 110vac and then discharge with a screwdriver just as you did there. throw out the bad ones. Also, point the terminal end away from you when energizing because they can explode and blow out at the top

When you do the Ohms test, the results you get are due to the following. The capacitor initially takes a charge and therefore shows what is in effect a current reading. When the capacitor reaches the voltage of the internal battery in the meter, the capacitor will be 'fully charged' (as far as that test set up is concerned) then no more current will flow into it and it will show an open circuit (or OL which is not really Overload). It is worth keeping the meter (set to a high resistance range) on the capacitor to see if there is a measurable resistance. This will indicate a capacitor with a poor insulation resistance and which will therefore not hold its charge. The snag with this test is that it is done at about 1 1/2 volts which doesn't stress the capacitor at all. The mains voltage charge/discharge test will only work some of the time even with a good capacitor. If the cap is disconnected from the mains supply at just that moment when the mains voltage passes through zero (it is AC), there will be no charge remaining in the cap. Indeed the size of spark you get will vary according to the moment when the cap is disconnected from the mains. If this mains test is done with a failed capacitor (short circuit in the cap) the results will be fairly spectacular. Take care!

man brother you are my HERO! After looking at 9 videos you are the 1st person/video that made sense

This video made the difference after watching 2 other capacitor videos. Thanks Chris

My wife had her friends over for a party while I was gone and someone stole my Fluke meter, When I complained she blamed me, I divorced her and recently picked up a mint Fluke meter at a garage sale for 20 bucks, Win Win!

I have that same meter and never knew of that setting. Big thanks for that one !

Thank you was trying to understand this just about to do my exam so far your the only person to show discharging

Thanks for doing this video. It had been awhile since I checked capacitors and this brought it all bad. My run capacitor is bad. Simple enough to get a new one and a lot cheaper than a new motor.

Excellent. Concise and to the point. You don’t waste people’s time. Congrats!

Nice video. Good thing you didn’t show that part with the 120 v.a.c. cord and screwdriver! LOL. I am a retired electrician and when done safely, electricity is really cool to mess with.

Got yourself a new sub. Your explanations are clear and straight to the point. 👍

Also, you can test each termination to the frame of the cap to be sure there is no current path between them.

Thanks for the explanation. I have a 10hp single phase Leeson compressor motor that stopped today, and started buzzing. I'm going to test the caps first.

Very helpful, the capacitor was the problem, had another capacitor off an engine that was sitting in the garage and it tested fine, engine now runs like it should.

1. Never discharge with a screw driver. Put your meter on DC put your test leads on the capacitor and it will drain it, that is the proper and safe way. 2. Put your meter on ohm's and your 9 volt battery in the meter will start to charge the capacitor if's it's good you will see the values going up rather fast depending on the charge of your battery. If it does not go up fast it's bad. I would suggest a stand lone tester the Supco MFD10 capacitor tester if you repair shit from time to time. Or a meter like the field piece SC640 which has the MFD option if your always working you can have one tool that does it all.

Right on..now I know how to use my Fluke multimeter to read microfarads

Great video. I've watched so many just trying to figure out how to test a capacitor attached to the relay of my lg fridge compressor. Even took it to couple of stores. One said it was good the other...it was bad. So confused. Your deliverance of the test method is the best so far. Thank you and God bless you. If you can also do a video on how to test start relays for a fridge that would be great....that's the next thing I have to figure out.

Chris you're the man. Thanks for the best explanation on the internet 👏

I have several meters from top end to crap and I only recently discovered that one or two of them has a capacitor test setting. I had always used the resistance test, needle up and then back to zero. Feeling a bit stupid on that! In my defense, on retesting a bunch of caps judged good by using resistance, the true cap test agreed. Seems like most caps are either dead or good with little in between - especially start caps that usually blow their top.

It's not seeking the GROUND It is seeking the SOURCE.

Always use a light bulb to discharge a range cap, then you can get an accurate reading and its safe. 👌

Hell yeah I've learned capitance.... again..... This time I will remember exactly how to do it on my 87,all the way till time to check my air compressor kicking the the breaker, see ya again then Chris

you seem to be a service tech who was taught by his daddy or uncle. I remember when i was trying to learn about motor caps and how to test them. I went to a bunch of appliance and motor parts stores and tried to ask how to test caps. no body was giving it up. they either did not know or understood the value of that information. It took me a while but I finally learned how to test them and understood the value of that information too. that knowledge helped me pay my rent and foot many many time over. And you know, if a customer knows hows and whys of a breakdown you won't get the service call. it blows my mind to think why people would devalue their knowledge. the only reason you make 80 to 200 or more per hour is because of what you know. but when you give it away it is worth nothing.

Thanks. FYI: @2:55, that's not a "u"; it's a lower-case Greek letter "mu", which stands for micro. (Mu has tails that go down below the "u" on both sides, longer on the left.)

The resistance test is not pointless. 1st because it shows if it is shorted or not. 2nd it shows you if it can take a charge or not and 3rd is when you switch the leads it shows you if the cap is discharging and recharging in the opposite polarity. So it's definitely not a stupid test

The best that I've seen on YT. Nice job Chris and thank you.

Just a quick note Make sure when discharging the capacitor that you are using an electrically rated insulated screwdriver !! Like the one he is using ...other wise it could jump through the handle

Very informative video. need to get a fluke meter it's a must have to diagnose electric systems. Thanks for sharing you are clear in your safety warnings but I wonder how many will find out the hard way concerning discharging the capacitor before testing it.

Thanks to this video i found the capacitor test function on my multimeter. I was confused as it is such an expensive Fluke multimeter, that there wouldn’t be a capacitor test function on it 😂 Just didn’t recognise the symbol for it. Confirmed that my start capacitor is bad & ordered a new one already 🙂 I found a water well in my backyard of which the motor doesn’t start, the motor only hums, i hope it works after replacing the start cap.

Very nice and informative, it would be helpful also to comment on the other ends of the testing probes as to which location they should be plugged into....Thank You

If the cap is disconnected from everything, the current will not flow to ground. It flows from one cap terminal to the other so it doesn't really matter if you're on concrete or not. The cap can still be very dangerous. You must discharge it before touching it with your hands or meters. A BIG TRICK is to discharge the capacitor like the book says; leave it laying on the bench and come back a little later, maybe a day later, and it will still knock you on your ass. A big capacitor does not loose all it's energy with a single quick short circuit. Short it every time before you handle the cap.

Thanks for the nice video and re-education, Another good way if you have to test live is use a switch and a piece of fuse wire but still make sure its discharged before touching afterwards

I've found readings on my ESR meter often give different results compared to simple capacitance testing with a multimeter, the two testing devices are complementary. Presumably that unreliability of a single test is one of the reasons HVAC techs simply replace the run/start cap when fixing or replacing motors. No test is perfect.

That third test using the ohm meter; you need to discharge the cap also for the small charge that is induced between application of the leads. You wont get a result that is correct otherwise!

Best explained video yet. Thank you

As an electromechanical tech for the largest wire production company in the continental U.S. there is a reason techs call that power cord a suicide cord.

Practical teaching -the best , thanks Chris for those graded tests methodically verified . Perfect 👌

Thanks Chris. I had no idea that -|(- meant capacitance. Every video I see always shows uF on the multimeter.

Just a note about the voltage stored in the capacitor: it's DC. Even though you applied AC voltage, the capacitor only stores DC. This is why caps are used in AC to DC power supplies.

Thanks, I like the way you explain everything about capacitors and how to read capacitance.

I bought a new capacitor that reads around 195 microfarads. The range on the capacitor says 161-193 microfarads. Does that mean the capacitor is bad? I believe the old capacitor reads even higher and neither capacitor will start my 1 hp shallow well pump motor. The motor will just hum and then goes quiet. I am working on the inside of the motor tomorrow checking things out to see if I can get it to run. I already cleaned the contacts on the inside but I broke a wire that was soldered and I got a new soldering iron to solder it back on. I also purchased some contact cleaner to make sure contacts are clean. My tester I believe was showing continuity through the motor contacts after sanding them lightly. If motor doesn't start I'll disconnect pump and try to start the motor without the pump to see if the motor will run.

i"m surprised you didn't show the most accurate test, while the cap is in circuit and energized. Use a clamp meter to read the amps on the start winding connection to the run cap and then multiply times 2652, then divide by the voltage reading across the capacitor's terminals which will give you the uf of the capacitor. Compare the result to the cap's label to determine if within specs. Can't use this for Start caps as they aren't energized long enough to take the readings..

Its a good actually very good video to learn. Thank you very much, Sir. Syed

Best video on testing capacitors that I've seen so far. Subscribed. Thanks!

Thanks out all the videos yours helped the most!

I'm trying to test the caps on an air compressor. One of the caps have resistors soldered into the terminals. Would those resistors cause the uf numbers to be excessively high and out of spec? the other cap is the same model and tests within range, but again doesn't have the resistors. Thanks for the video.

On the capasitor setting, the on I have goes up the .OL in both directions. One side is higher than the other. So I guess this cap is bad? The resistance test goes up then .OL, jist like the cap test, but higher numbers.

Well done ! God bless you Chris !

Thanks Chris. Your video is really good and very informative. I watched 3 other videos and I was doing it wrong and ready for a new CAP (was getting 0L). Now I know my capacitor is good. And God bless auto-ranging meters :)

Can I use the first test or should I say ,will it work to test the capacitor on my pressure washer ? I am not that great with electrical stuff but your video seems straight forward. Thank you.

I know his trick, he is only good at what he is doing is because of the inspector you can see at the end of the video making sure he is not making any mistakes!

Thank you Chris. I have been testing my capacitors incorrectly.

Very beneficial and informative video. Thank you!

good video,thanks

I had a hum and then the breaker tripped. I actually found a broken wire on the capacitor. I am back in business.

Thanks for useful information without the history and the theoretical operation of a capacitor. Hopefully will be repairing my AC for $11.00.

I had no idea about the capacity setting on a multimeter, so that was especially helpful. I had been staying with my older multimeter because it seemed to do everything I needed to, and honestly, it's not auto-ranging, and for some reason, I had it in my head that the non-autoranging ones were better. I guess because it required the user to be more knowledgable. This video has me reconsidering that stance. Any thoughts/recommendations? Thanks!

Like your assistant.

great video, i learned something new

Thanks, though I hated how close your hand was to the exposed conductors when performing the 'firecracker' test! When you pulled the plug out nearly swept them with your left hand. Please don't try this at home without taking far more precautions than Chris here!

I have watched dozens of videos this is the best thank you 🙏🏿

Very helpful video; my pool pump has a Genteq 25 uf 2-pole capacitor; the wires from the pump are black and were disconnected from the capacitor by my electrician when he removed the capacitor; I bought a new Genteq 25uf capacitor; I don't know which wire to connect to which connector on the capacitor; does it matter what wire goes to what connector?? Thank you. Steve

Try discharging the capacitor first before testing on your last test and it will work every time 👍

Good video,please keep them coming!!!

On the capacitor in this video, what is the little button thing next to the terminals?

Excellent!

That second "test' is totally stupid. you plug and unplug into the mains and you have no idea at which part of the ac cycle you are disconnecting. it could be at the peak = 325 volts or it could be zero volts or anywhere in between. The test is meaningless. If you are hoping to check that the cap holds a charge then you need to measure the voltage on the cap immediately and then several minutes later to see if the voltage is the same. Those are film capacitors and they do not have much leakage. If the voltage drops then the cap is bad.

Thank you Chris , Great videos , I have a problem that you may be able to answer my Frigidaire affinity atf 705b stopped working during a cycle , and i went through the the normal things that typically goes wrong like , door lock , main front control board, computer board, checked all wires for short or breakage, ( all ok ) , but when i looked at the run or start capacitor it didn't have any marking on it numbers or writing , so don't have a clue what reading it should have , so how do i check if its ok please, thank you if you can help .

real world stuff. Thank you! I have one reading just below the 5% range.... 41.17 of 45 uF rated +/-5% ... I'm inclined to think that this isn't the problem.. Replace anyways?

The only way to test a capacitor is by ESR. The correct resistance of the inner dielectric tells you if a cap is bad or good.

Now I know. Thank you.

What if the meter reads OL when checking the capacitor. I have an AMES. It reads one Capacitor but not the other.

👍👍 mystery gone on how to test

For the second test, when you're applying live ac voltage to the capacitor terminals, what if there is an internal short in the capacitor?

Bro! Thanks for tutorial!! It’s helps!!

excellent helpful video thank you

Cool thanks! Am I the only one wondering why the lighting exposure freaks out only when you have the test probes on the poles of a cap? Is some kind of stray flux from the low powered test freaking out the electric eye that determines the brightness? Not complaining -- I think it's fascinating

Thanks. You helped me a lot 👍🏻👍🏻👍🏻

I'm trying to get a 1 hp Baldor going that growls and has trouble getting started, once its hand started it runs fine. The capacitor had foam rubber padding wrapped around it and it deteriorated and ruined the printing on the unit, but I have another motor like it and was able to decipher the info. My question is a Packard capacitor made in China costs under 9 dollars and the Baldor made in USA is over $45. Your thoughts on if I should gamble on the cheapy one? The motor is a spare and will see use occasional on the farm. Thanks for your video, very helpful.

What do you do if a start capacitor has a discharge resistor soldered in, how do you measure?

Thank you

Thank you for sharing!

I have a cheap multimeter that has the capacitor symbol on the dial. But there are no buttons to press, just a hold button and a button to light the display. I can't press anything to get microfarads, and the capacitor setting doesn't seem to work. It is an Astro AI AM33D

Great video man thanks, keep up the good work.

Why isn't my meter showing any capacitance on any of the new run capacitors for my furnace? I thought I bought a bad one (7.5 x 370) from Grainger because it and the suspected bad one it was replacing were both showing 0 capacitance on my cheap meter. So I returned to Grainger with the suspected bad one I just bought from them, the suspected bad one that came off the furnace and my meter. They brought out several new capacitors and my meter never registered any capacitance on any of the capacitors. So my question is why is my meter not showing any capacitance on ANY capacitor? Thank you.

Small question, the 40 microfarad one, that was giving 35, should be a start capacitor, not a run capacitor. Am I correct here?

Would not a power strip with an on/off switch activated for one second be better than plugging and unplugging the receptacle end of the wire?

My air compressor (single phase motor) starts and runs fine, but..... I have multimeter with capacitance reading and run capacitor is in the tolerance (nominally 40uF +-5% and i measured 40,2uF) . My start capacitor dont have tolerance labeled and is 100uF nominally but i measure 186uF. Is it something to be concerned about? It looks like new, no swelling, discoloration, smell etc.

I like sparks 🎉

Great video. Thanks

That's not an insulated screwdriver!!

I’m looking for this video👏👊

Great vid.

Is it possible that the energy in a capacitor discharges actually in the form of direct current? A/C is created by A/C generators at the power plant.

good work

Put it in for 1 second and pull it out....that's what she said! And I didn't even spark, I guess my capacitance was not up to par.

Very helpful, thanks.

Do I need to discharge a newly packaged capacitor as well if I want to test it? Thanks. Gr8 video. No words but thank you!!!

Super quick question. Replacing my air compressor run capacitor and the new one has a blue and brown wire. I have to connect them to a black and white wire from the compressor. How would i go about determining the right combo? Thanks!