Could a capacitor like this be used to start an induction motor? I know there's start and run capacitors,but dont know if you could swap one for the other?
Yes, an oscilloscope would help to see if the capacitor is bad. It will show a waveform applied to capacitor and how the capacitor responds to the waveform. I am still learning how to use mine. I've tinkered with it from time to time and had thought of doing a video how to use it. -MrFixit
Love the videos!!! keep it up! Here's my problem (hopefully you can help). Our 1 year old Kenmore range microwave started to hum loud and burning smell and no heat. My research said could be the diode, capacitor or transformer. I had another older Kenmore range and I took the diode out of it and tried it in the bad microwave (AND YES, I DISCHARGED THE CAPACITOR 1st). Now the loud hum seems to be gone but still no heat. I'm only 99.9% sure I wired the red wire and white wire to the capacitor as well as the diode correctly :( Any suggestions would be appreciated...
a good video for begginers and professionals. you are great Mr Fixit! well, my microwave oven just stopped working and the display shows only a zero. the screen is lit, but nothing moves no humm nothing except a zero on display. what could be causing this?
Used the capacitor setting to test a microwave capacitor and numbers were fluctuating up and down between 0-.50, stopped for 5 seconds ,then continued. Have you seen them fluctuate like this before ? I'm assuming the capacitor is faulty if it's fluctuating up and down like that every 5 seconds?
I never got to see a pocket one, I was just trying to think of easier way of you testing bad capacitors, in circuit , if you have a two channel scope and you probe both sides of it, and just feel it to see if it is getting warm, I know a ESR is the way to go, but I have a buddy that uses the scope for everything and just makes what I find real hard, look so easy, but I think that he is so good he just knows what to expect from a good filter, he does TV Repair, I am just still learning and lost.
I was wonder if I can use all the parts from one micrwave to make my 24VDC power supply for power tool that draw 6amp? 1. rewind Microwave transformer 20 turn 2. Rectifile from microwave 3. AC Capacitor from the microwave Thank you for the video
No, I don't mind, MrMac. Everyone else does. Isn't ESR meters used to test the internal resistance in battery packs? Never heard of them being used to test a Capacitor. I rarely use the capacitance tester since I've had better results using an ohm meter to test them. -MrFixit
OL means OPEN LINE not Over the Limit. OPEN LINE means infinite resistance which happens if the test leads are opened apart with no conductance between them.
Hi, I'm George ,I have a 1.14uF cap in my panasonic microwave I have permormed the test in your video capacitance meter shows 1.13 that is close enough but the resistance test settles at 25Mohms, and when i insert a 10meg resistor accross it settles at 7.5meg , this tells me 25 in parallele with 10 makes 7.5 , what is your opinion of this , also the magnetron reads zero Ohms it was an aftermarket AM703 , i think i have to buy another one , Thank you Cheers George
So after my microwave made a very loud grinding noise. it still comes on, but all i hear is that buzzing sound.... I know the Magnetron is still working because I test that by putting in a simple chocolate treat to see if it was heating. and yes it is heating. but its very quite now. like normally you turn on a microwave, you get the buzz, then it like ramps up, or a fan or something comes on, that is not happening. And Ideas?
Which is the positive and negative terminal on a microwave oven cap? Are both top terminals positive with the case negative as in a electrolytic cap. if polarity not correctly hooked up the cap will be damaged. My cap tests excellent as per your video but I need to know how to hook it up correctly just like a electrolytic cap.. I am using the cap for a hi voltage setup I am experimenting with.
+Thomas Ferko Microwave oven capacitor's are not polarized. They are monolithic capacitors. The terminal can be positive or negative and doesn't matter which one is which. The case is grounded in the event the capacitor shorts. -MrFixit
I am doing some research into capacitors, which are a fairly new thing for me to be getting deeper into. I would like to know, how the capacitor is charging in this video, like what is powering it. dose it have a battery, or an input that is not seen in the video?
Great explanation, thanks for the video! Question: Why does the digital multimeter show 20MΩ → 10MΩ when starting from a discharged capacitor and 5MΩ → 10MΩ on subsequent readings? The 5MΩ → 10MΩ makes sense to me: As the capacitor is being charged its resistance increases, up to a point where we’re looking at just the 10MΩ from the internal resistor. But the 20MΩ → 10MΩ I don’t understand…
Modern HV Microwave capacitors have an internal 10 Megaohm Resistor (known as a Bleed Resistor) connected across the terminals. This is to safely discharge the capacitor when the power is removed. The first test determines if the 10 Megaohm Resistor is functioning as intended. Ohm Meters start from their highest measurable value, in this case, 40 Megaohms. As the tester applies current to the capacitor, it is measuring the resistance. The values are decreasing as it measures the resistance in the Capacitor but at the same time the resistance is increasing as the Capacitor is charging. A 1 microfarad Capacitor does not take long to charge. By the time it dropped to 10 Megaohms the capacitor was nearly at full charge, as to why the Values were slowing down then stopping at 9.76 megaohms.
Thanks for the safety comment. I need a clarification since I am new to this. I am not attempting anything until I am sure so I have a lot to learn by reading first. This is the part I need to understand: Your comment is in quotes. 1. "This case: high voltage cap, if charged it can take a while to discharge or worse the internal resistor is busted and it doesn't. In this case it could sit there at 2kV you touch it or try to put non-insulated/poorly insulated alligator clips on it and the high voltage in there happily zaps you with potentially lethal results, hence make sure it is discharged entirely. My response: Yes, I understand this part. 2. "Same goes for "just mains rated" filter caps and what not in any transformer on the mains side even if the appliance has been unpowered for a long time." My response: A. What is "mains" and "mains rated" and "mains rated" filter capacitors? B. When using the word "transformer" are there transformers in a microwave that remain charged if the microwave is unplugged and the capacitor has been discharged, disconnected and removed from the microwave?
The "mains" refers to the primary power source going into the microwave. Some microwaves use a Mains Filtering capacitor to filter out electrical noise created during operation. The HV capacitor is used to double the output voltage from the Transformer. The newer HV capacitors have a built-in 10M ohm resistor to bleed the Capacitor's Charge. To ensure they are discharged you must use an insulated tool to short the terminals on the capacitor before removing the capacitor. The jumper alligator clips are then used to keep the capacitor discharged until you're ready to test the capacitor. If replacing the capacitor, the new capacitor must match the same ratings as the original. Transformers cannot hold a charge because they depend on induction. for them to work. Meaning current has to flow thru the transformer to for it to work, as to why all electical power must be removed before service.
ESR is the best you can tell if a cap is no good, if its going to heat up etc. the tester puts a 100 k hz sine wave threw the cap to see its internal resistance, and yes you can predict a battery losing its life threw testing the internal resistance, it would be a great video showing people how to make a ESR, home-made parts 20 bucks, to buy $100 to $150 for a good one. waiting for your next video.
I'm working on a GE Micro and forgot the placement of the diode lead to the capacitor. Does it connect with the red wire lead to the magatron or the white wire? What would be the result if it was connected wrong. Thanks for your time...
You can probably find a YT vid w/ that info. I would recommend taking a picture of such wiring before taking anything apart. Seems dangerous to have to guess or remember wrong.
Is there wny way to know which capacitor mf. value must be used with a specific magnetron? I think mine was replaced with one that is not the same value of the original and I´ve read that it may cause a low heat or a premature magnetron damage. I´ve looked on the internet and can´t find a chart where each magnetron model has the value of the capacitor to work with
The capacitor is not an AC capacitor. It is a non-polarized DC capacitor. AC capacitors are often used in electric induction motors to start the them up. They can store a DC charge but they cannot store as much as a DC Capacitor. The Resistor in HV capacitors is used to drain the capacitor's charge when the power is removed.
You are unable to test for dielectric leakage which causes failure of capacitors. You must apply DC working voltage to do this. But since you have a shunt resistor inside, the effect is equal to dielectric leakage.
maytag microwave fan stays on all the time, no level 1 speed, just 2 3 4 5. The fan won't turn off. Can someone please help me? If I unplug the fan connector, everything seems to work fine, even the fan controls ie level 12345off. Thanks.
I tested my microwave capacitor per your demonstration. I get 10.12 Mohm. There is a little amount of black residue and some needlepoint pitted spots on top of capacitor beside the plastic protectors of the poles. Question.... Is it possible that the tests can all be good, but the capacitor will not charge all the way to 2200V in order to power the magnetron?
You need to discharge the capacitor, and use the Ohm tester. The capacitor should show a steady increase in resistance up to 10M ohms. IF it Flat reads 10M ohms after the Discharge than Capacitor is dead and needs replaced.
+offonroad If everything is working but there is no heat, Then the problem is a bad relay, door switch, HV Diode or HV Capacitor. If the control panel is working but nothing turns on, there's a bad relay or control board. -MrFixit
hi I have an issue with the microwave... issue is blown fuse everytime I open or close the door.. checked my door switches... and the monitor switch was bad. ..I swapped it out for a new one and the fuse is still blowing out! stuck atm .. I don't think its on the high voltage side because the microwave isn't in use. just opening and closing door causes fuse to blow any help would be appreciated thanks in advance
There is a 'safety' interlock switch that is wired to blow the fuse if the MW doesn't shut off when the door is opened. The primary and safety switches are interlocked. The primary switch opens then the Safety switch closes. If both are activated at the same time the fuse blows. Double check the wiring and the switches. -MrFixit
Okay it's a bit of an old comment I'm replying to here but even if you don't read it anyone that doesn't know it can learn I guess. When dealing with any cap rated for a high voltage and even low voltage ones always depower your circuit and discharge unless you know entirely know what you're doing and know that depending on what your test gear is set to it or the appliance can be damaged (don't mess with it unless you know what you're dealing with). This case: high voltage cap, if charged it can take a while to discharge or worse the internal resistor is busted and it doesn't. In this case it could sit there at 2kV you touch it or try to put non-insulated/poorly insulated alligator clips on it and the high voltage in there happily zaps you with potentially lethal results, hence make sure it is discharged entirely. Same goes for "just mains rated" filter caps and what not in any transformer on the mains side even if the appliance has been unpowered for a long time. Low voltage but reasonable capacity capacitors are unlikely to kill or zap you but for example put your multimeter on ohms or current on it and depending on the quality of your meter you can bust it or blow a fuse. Some meters for example will survive resistance setting on mains (my fluke and Agilent properly cat4 rated ones) but I won't do it or ever suggest to try it. I like seeing the test in reviews on the eevblog channel by Dave Jones, many cheap meters died that way ;) But yeah basically use common sense observe visually first, understand what it is if needed learn about things and when in doubt measure volts first. The high input impedance should protect you and the meter, don't touch mains powered devices unless your meter is at least of a proper brand and cat 2 or better rated for that voltage. Even then preferably do it depowered if possible, if not attach probes beforehand then power it up and operate the device. And if you don't really know what you're doing just don't touch anything like microwaves, old CRT based tvs and monitors, etc. They all involve high voltage caps that can hold a charge for a long time.
It's RC Time Constant, look it up in Google! It takes some time to bleed the capacitor through resistor, depending on the size of the capacitor, and the value of the resistor!
wow 2200volts 0.9uf?? my motorbike ac cdi is using a tiny 400v 0.6uf capacitor, will this capacitor boost my cdi spark ignition plasma output? fantastic clear explanation even a cat can comprehend this! great video! thank you comrade fixit!
my cat put in the right capacitor and made it resonant RLC, now shes self looping...I can even hydrolise water with it..Don Smith was correct afterall ;)
What about my 100kHz LCR meter ? Should I throw it in the trash ? What about equivalence series resistance (ESR) ? Isn't that a better way to test capacitors ? Please, I'm in the dark here. >
TOOK IT APART,AND TRANSFORMER IS CHARED/BURNT IN 2 COPPER WIRE SPOTS ON BOTH SIDES. DOES THIS MEAN I NEED A NEW ONE TRANSFORMER? IF SO, WOULD THERE BE A GOOD CHANCE IT ALSO FRIED THE MAGNATRON AND CAPACITOR ? OR NOT?
I apologize for the delay in response. The Transformer will have to be replaced. for the price of a new HV transformer you can buy a new microwave oven. The Magnetron may be damaged that caused the Transformer to blow. either way you're better off buying a new Microwave. -MrFixit
The HV Capacitor in conjunction with the Diode doubles the High Voltage Output from the Transformer for the Magnetron to operate. The Process is called Half-wave Voltage Doubler. MrFixit
A bad capacitor can easily pass this type of test and still be completely faulty. There is no mention of the ESR (equivalent series resistance), nor of leakage current (IL). The IDEAL capacitor, indeed, has no leakage current. In practicality though, this is not the case. These types of failures essentially turn your capacitor into a resistive load, increasing internal temperatures, and creating even more resistance. Even when the capacitance can be quantified as within the manufacturers specifications, this type of test alone is not sufficient to call the capacitor good.
Ian Coloma A crude way to test a Capacitor with an analog meter is to use the Ohm setting. You will need at least a 100 MΩ meter. Keep the capacitor shorted and attach the test leads. Should read 0 Ω. Remove the short. You should now see the resistance begin to rise steadily. As the Capacitor stores the electrons the resistance will increase. There is a 100 MΩ bleed resistor built into the capacitor. The resistance should equalize between 50 and 100 MΩ. -MrFixit
Sounds like you have a hole forming in the inner cavity. It happens when the paint inside the microwave chips and moisture corrodes that area making a hole and when that happens the microwaves hit the edges of the hole causing it to spark. It could be repaired but it would require welding a new plate where the hole is and then painting it with corrosion protecting paint. The paint may also help to deflect the microwaves
The charging comes from the test meter. The yellow wire was used to keep the cap from charging. When removed the tester applies power thru the cap and measures the charge capacity of the cap.
Non-Polarized capacitors do not have a Positive/Negative polarity. Voltages higher than their declared rating will certainly damage the capacitor. Polarized capacitors do have a Positive and negative terminals. These capacitors are specially marked with the + for Positive terminal and a - for the negative terminal. Reversed polarity will damage the capacitor as well as exceeding the voltage rating.
Don't rely on that test, I have tested air conditioning capacitors show good on a capacitor tester but if you put it on a ESR Meter it will show the actual AC passiveness of the Cap measures perfect on a cap tester, but 20 ohms on a ESR fails also through a hundred volts across it, to test for leakage. Those large caps are expensive about $30 bucks. Ohm test and Cap test these days are not reliable. Maybe just to see if shorted or open, but no way accurate. Hope you don't mind my 2 cents.
Mark Hodgson you can't, if you take the resistor out then you have to open up the capacitor. UNLESS you can manage to weld the aluminum top back on then it will probably still work with less internal resistance meaning more something, Amps, volts, farads, etc. if you manage to remove it and get the capacitor back together, if it works please make a video about it, sounds pretty cool.
Don't know, I haven't spoke to him in a week, Master. He keeps saying he's going to do more videos. Hell, he's probably waiting for me to do it for him. -MrFixit
Hi, I have a 1.05uF capacitor that I need to replace. 1. Would a 1uF replacement be OK ? 2. If I don't use the exact capacitance would it change the microwave wave frequency (The reason I ask is because the chamber is build to keep micro waves at a specified wave frequency. If I change it, a radiation leak can occur as I understand) ? 3. Is it safe (safe I mean that the capacitor would not explode or melt and cause fire) to buy anonymous capacitor from online websites (like Aliexpress) ?
1. I think it will be ok. Probably the tolerance of the capacitor is more than 5%. 2. No. It's not a part of resonant circuit. Frequency that microwave oven generates depends mainly on physical dimensions of magnetron cavities. The HV capacitor is simply a part of voltage doubler circuit. Slight difference in capacity may at most transfer to little different voltage powering the magnetron, and the generated power, but it would be difficult to even notice that difference. 3. I think they are safe. After all the capacitor that your oven originally had, was made to the similar (chinese) quality standards. :-)
Must be your profile pic. It's scary as fuck and maybe he thinks replying to you will link your evil demon clown face to his soul at night causing him to have nightmares that manifest your avatar into his dreams and kill him. Yes I know this sounds bat shit crazy but it does add up
You should be called: *_Mr Fuck It Up !_* > I know you gonna delete all thepe post but my pleasure is that you've read them ! If they remained, I would know that you had never read them. Go on ! *_DELETE !_* >
