In the circuit board assembly, there are a lot of electronic components like transistors, capacitors, integrated circuits (IC), etc are used. When due to any reason components get defective, they need to be replaced with a new one to repair the device.
During troubleshooting, it needs to identify the faulty component by doing measurement with the help of tools or visual verification.
Specifically, if we talk about the capacitor because they are highly sensitive to spikes and over-voltage can burnout and damage the capacitor permanently.
In this article, we are going to discuss How to test capacitors to identify defective or working conditions to repair. How to test a capacitor with a multimeter or other tools to troubleshoot.
How to Test a Capacitor with a Multimeter
How to test ac capacitor with a digital multimeter and also how to check capacitor without a multimeter.
1.Using a Digital Multimeter With Capacitance Setting
This is the most common and the easiest way to test capacitors with the help of a digital multimeter having a capacitance meter feature. Nowadays maximum digital multimeters have an inbuilt capacitance meter.
This method is also applicable to tiny SMD components as well. How to test ac capacitor with digital multimeter find below a step by step guide
- De-solder the capacitor from the circuit and make sure that the capacitor must be fully discharged to get an accurate measured value.
- Not down the capacitor value on its body that was mentioned in Farads as the unit for capacitance is the farad normally in microfarad ( µF).
- Turned the knob and Select “Capacitance” settings on your multimeter
- Connect the multimeter probe to the capacitor terminals. If it is polarity Connect the positive terminal with red and the other with a black multimeter probe.
- Check the multimeter reading on display and note down the actual reading on paper.
- Compare both readings and If there is a huge gap between the printed value and measured value or shows zero value it means the capacitor is faulty and replace with an OK one.
2Using a Digital Multimeter Without Capacitance Setting
A few Digital Multimeters do not have the capacitance feature so the above method is not applicable but still we can check the capacitor by measuring resistance value.
Below is the Step by step activities on how to test a capacitor with a multimeter with a resistance value
- De-solder and remove the capacitor from its circuit and ensure that must be fully discharged.
- Set the Multimeter knob to Ohm ( unit of Resistance) or geek letter omega (Ω) as shown in fig.
- Connect the multimeter leads to the capacitor terminals and ensure again for the red one on positive and black for the negative terminal.
- Check and write down the initial resistance reading shown on display. Soon after showing some value for a short time, it sets to display an infinity (Open) value.
- Disconnect the probes and respect them again and again. If shown the same results as the first time it means that the capacitor is OK.
- And if there is no change in any of the repeated tests it means that the capacitor is faulty (dead).
Test a Capacitor using Simple Analog Multimeter
We can check the capacitor just like the digital Multimeters by using other parameters like Current (A), Voltage (V) and Resistance (O), etc. In this section, we will test the capacitor with help of resistance measurement.
Below is the Step by step activities on how to test a capacitor using Simple Analog Multimeter
- Repeat the same Step again -De-solder and remove the capacitor from its circuit and ensure that must be fully discharged.
- Set your multimeter knob on to its resistance setting ( Ohmmeter Ω) and select for the higher range.
- Put the red probe on the positive terminal and the black probe on the negative terminal.
- In analog multimeters, the needle pointer on display measures the reading and the position of the needle determine the capacitance outcome.
- If a needle on display initially has a low value and after some time moves to the right side and displays a higher value it means that the capacitor is OK.
- If the needle initially shows the low value and does not move further it indicates that the capacitor is faulty and internally short.
- In the third scenario the needle does not show any resistance value and does not move right or further for any value it means the capacitor is open and faulty.
Testing a Capacitor With a Voltmeter
Here we learn how to test the capacitor by using a simple voltmeter and get the voltage rating of a capacitor to check for defective or good identification.
Below is the Step by step activities on how to test a capacitor with Testing a Capacitor With a Voltmeter
- De-solder a capacitor and remove it from the circuit after getting fully discharged. You can also try removing one lag for measurement.
- Check the capacitor’s voltage rating outside the capacitor body and note down on paper displaying it on the meter. It is a number printed on the body followed by a capital “V,” like 16V,50V, or any other value.
- Now Charge the capacitor with a known voltage source that has less than the rated value. For example, if the rated capacitor voltage is 30 V Charge it with 9 V and 600 Volt charge it at least with 400 V.
- Let it charge for a few seconds but ensure that the Red probe connects the positive terminal and black for the negative terminal.
- Now the next step is to Set your voltmeter to read DC voltage settings and measure the voltage of the charged capacitor by connecting the red probe to positive and black probe from the negative terminal.
- If the measured value is close to the rated value it indicates that the capacitor is good. If the voltage gap is higher then the capacitor is faulty.
Shorting the Capacitor Terminal
In the old-time, this method was more popular because it did not require any measuring device for validation. How to test a capacitor without a multimeter will discuss steps here
This method is risky and not recommended by professionals but if required to conduct needs to take safety precautions. Need to wear safety gloves and do not touch any conductive metal surface. Below is the Step by step activities on how to test a capacitor by Shorting the Capacitor Terminal. How to test the capacitor below steps are involved
- Disconnect the capacitor by de-solder from the circuit board and the capacitor must be discharged completely.
- Connect red to the positive terminal and black with the negative terminal of the power supply for 1 to 4 seconds.
- Now short the capacitors from a metallic wire or rod while taking safety precautions to prevent electric shock.
- The strength of the spark gives the indication of capacitor charging capacity. If the spark is strong and long the capacitor is in good condition. If not, the capacitor is faulty.
How to test a capacitor with a multimeter in a circuit
Now another question is how to test the capacitor without desoldering or without removing the capacitor from the circuit board.
When a capacitor is mounted On the circuit board it is not possible to measure the actual rated value through the multimeter or capacitance meter because there are several other components placed in the same circuit board. Due to that capacitor gets equivalent value rather than actual.
Now again the question is again the same: how to test the capacitor without desoldering the component and if yes how it is possible.
Yes, it is possible by using an equivalent series resistance (ESR) meter or smart tweezers both work fine but the ESR meter more suitable for through-hole components and smart tweezers for tiny SMD components. How to test capacitor without Desoldering Below 3 methods are used to identify the faulty capacitor.
1. Test a capacitor with ESR Meter
The ESR meter device used to determine the equivalent series resistance of a capacitor without desoldering or removing it from the circuit board. This device can not measure the capacitance but can test the capacitor. You Can Buy online (ESR meter (Amazon Link)
- To test the capacitor first and important step is to discharge the capacitor completely. To discharge you can short the capacitor terminal with the help of metallic items.
- Turn on the ESR meter and contact the red leg with the capacitor positive terminal and black with the negative terminal. and short its leads till display zero reading.
- Note the reading of the ESR meter and note it down.
- Now compare the noted table reading on the body of the ESR meter. If the gap is within range then the capacitor is OK and no need to change.
- ESR is not giving any table you can check with a capacitor datasheet and compare it with the measured value.
2. Smart Tweezers
Smart Tweezers are more handy and Portable to do jobs more fun and comfortable.ESR Meter is not more reliable in dealing with the tiny SMD component.
But the drawback of smart tweezers is that they are too costly otherwise they work very smart and effectively. (Smart Tweezer (Amazon link)
3. Visual inspection for Bad Capacitor
Sometimes you can check the capacitor by visual inception rather than using the smart tweezers or ESR meter easily.
A faulty capacitor gets swallowed on the top side and gets some damage or burnt remarks on the body. If you find such observations during inspection then replace the suspected capacitor for fresh.
Now you will get the answer to the query for How to Test a Capacitor with a Multimeter in both conditions removing from the circuit board or with the circuit board. And also how to check capacitor without a multimeter.
Faulty capacitors can be identified by digital multimeters, ESR meter, and also usage of smart tweezers. how to test a capacitor with a multimeter in a circuit answer is ESR meter and smart tweezers.