Capacitors have found their usage in almost every electronic equipment, and also in power conditioning, energy storage, pulsed power and weapons. Generally, while troubleshooting or repairing such appliances, the common question that arises is that how to test and check the capacitor?
Types of Capacitors
Here are some types of capacitors that you will find in your electrical appliances:
These capacitors are polarized ones and may be only used in DC circuits. Generally, aluminium electrolytic capacitors are mostly found in several applications such as power supply, decoupling capacitors, computer motherboards and many domestic appliances.
So, if you want to test electrolytic capacitor of your device then your multimeter can do that too.
Ceramic Disc Capacitors
These capacitors are small in size and are ideal for higher frequencies. You will find them in almost every electrical equipment. Moreover, such capacitors do not have polarities, so you can connect them on a circuit board in any direction. This makes them more safe to use and measure.
So, if you are measuring frequency of your radio or some audio application, then you are actually testing the ceramic disc capacitor with your multimeter.
These ones are also small in size but have greater capacitance. Additionally, they offer long term stability and reliability, so they are costly as compared to other capacitors.
However, they are commonly used in household circuits, medical electronics, audio amplifiers, and for power supply filtering on computer motherboards and cell phones. Moreover, your high-end multimeter can easily measure capacitance across these devices and will help you in troubleshooting them.
Surface mount device (SMD) capacitors are smallest in size as compared to the above ones. They are widely used in modern printed circuit boards for manufacturing of electronic equipment. Besides, they are much faster and more reliable when it comes to the construction of circuits.
SMD capacitors are now commonly used in many devices which assists you in your daily tasks. And if they aren’t working properly, then they might hinder your activities. So, to check the status of your capacitor you need a multimeter.
How can you test a capacitor with a digital multimeter?
Digital multimeters are the best devices to test capacitors. So, get your multimeter and follow these simple steps:
- First, disconnect the capacitor from the device and make sure that the capacitor is fully discharged.
- Check the capacitance value which is written on the capacitor and then select the capacitance mode on your multimeter.
- Now, you need to connect the testing probes with the terminals of the capacitor. So, for this connect the positive red probe to the anode of the capacitor and the negative black probe to the cathode of the capacitor.
- Check the multimeter reading – if the measurement shown by your multimeter is close to that printed on the capacitor itself then it is a good capacitor, but if it is zero or significantly less than that, then it means that the capacitor is dead and it is time to change it.
Now, you must be wondering: what’s meant by a good or bad capacitor?
Well, good capacitor is the one which initially shows low resistance and then gradually increases towards infinity. While, short capacitor shows very low resistance and open capacitor will not show any movement.
How to check capacitor by using a digital multimeter without the capacitance mode?
However, if your multimeter is very basic and does not have advanced features to check what’s going on with the capacitors, then that simple one, on its resistance mode, can do the job too.
Must be curious to know how, right?
Then, let us share some simple steps and you won’t go wrong with them:
- Remove the capacitor from the circuit and make sure that it is discharged.
- Select the resistance mode on your multimeter, this setting may be marked with the symbol Ω or with the word ‘ohm’ on your multimeter. Moreover, if your multimeter does not auto-range then you have to select the range and we’d say to set the range of resistance to 1000 ohm = 1 k or higher.
- Connect the multimeter leads to the terminals of the capacitor. Make sure to connect the positive red probe to the anode of the capacitor and the negative black probe to the cathode of the capacitor.
- Your digital multimeter will show a reading for some time, note it before it disappears and returns to the OL (Open Line).
- Now, disconnect and reconnect the multimeter with the capacitor. If you observe the same reading as the first one, then the capacitor is good. However, if there is no change in the resistance value on any of the tests, then the capacitor is dead.
How you can test a capacitor with an analog multimeter?
If you have an analog multimeter, still you can measure capacitance with it. Just follow these steps:
- Make sure that the suspected capacitor is discharged and disconnected from the circuit.
- Set your multimeter to resistance settings marked with symbol Ω or with the word ‘ohm’, as in the digital one.
- Connect the multimeter leads to the capacitor terminals, the red lead goes with the positive terminal while the black lead goes with the negative terminal.
- In the case of analog multimeters the readings are shown with the help of the needle. So, if the needle shows a low resistance value and then moves up to infinity, then the capacitor is good. But, if the needle shows a low resistance and does not move, this indicates that the capacitor has been shorted out and needs to be replaced. While if the needle does not show any movement or any resistance value, then it is an open capacitor.
Now, you probably know how you can test the capacitor, and if it is bad or dead change it. This will save you from heavy bills which come when any household appliance or any device gets fixed.
Hope you have found this article useful and can test and check the capacitors with ease. Just don’t forget to get through the user’s guide before you start.