The multimeter is the gauge of choice when it comes to testing a potential faulty capacitor. There are several ways to check a capacitor using a multimeter.
However, it applies:
The multimeter requires a particular measuring device to check capacitors and thus to be able to determine the exact values of the capacitance of a capacitor. If there is no capacitance measurement function, it can only be determined if the capacitor has a short circuit or if it is being charged. For this, a continuity test or a resistance measurement in the kilo-ohm range can be carried out.
What is a capacitor?
Capacitors are a passive electronic device used in almost all electrical devices. It can be found in computers, televisions, kitchen appliances, craft machines, vehicles, and many other devices.
Capacitors consist of two electrically conductive surfaces, which are separated by an insulating material. However, there are different types and shapes of capacitors. One of the best known is the electrolytic capacitor, also called Elko. This is a polarized capacitor. In contrast, for example, ceramic capacitors are used as non-polarized capacitors. In the field of motor capacitors and the starting capacitor or starting capacitor is a concept many people.
Since capacitors block DC and pass AC, they have different functions. In an AC circuit, the capacitor is used as an AC resistance, in a DC circuit, it can store an electrical charge. This stored voltage is called electrical capacitance (C) and measured in the unit of measure Farad (F).
As electrolytic capacitors (electrolytic capacitors) wear out over time, it may be necessary to check their functionality. You can measure a capacitor with the multimeter. There are two approaches: Do you just want to check the condition of the capacitor with the multimeter, or do you want to measure the exact capacitance of a capacitor?
The following section outlines how to use different methods to test a capacitor using a multimeter.
Check the capacitor with a multimeter without capacitance measurement.
If only a simple multimeter with no capacitance measurement function is available, only the rough functioning of the capacitor or electrolytic capacitor (Elko) can be checked. The procedure is as follows:
1. Expose condenser
First of all, the capacitor to be tested should be removed entirely from the circuit. All contacts to the circuit must be removed, and the poles of the capacitor made freely accessible.
2. Visually check the capacitor
Before the capacitor is measured with the multimeter, it should be visually checked for visible damage. Pay attention to small bumps or fine cracks on the surface. Even escaping liquids suggest a defective capacitor, which should be replaced.
3. Discharge capacitor
The next step is to make sure that the capacitor is completely discharged. To ensure that there is no residual current in the condenser, it can be connected to a consumer such as a simple light bulb. In this way, all stored energy can be discharged entirely.
4. Set the multimeter
Now the multimeter should be set to the resistance measurement function (measured values in ohms). In this case, a measuring range of 1000 ohms, so 1-kilo ohms to choose so that you can find usable results.
5. Measure condenser with a multimeter
Now the two test leads of the multimeter can be connected to the poles of the capacitor. For a complete text of the condenser, the test leads must be applied twice and the reaction of both processes compared:
On the display of the digital multimeter, a measured value should now be displayed for a fraction of a second, which must be remembered. Then the measurement display will immediately jump to OL (Open Line). If the test leads are removed and recreated, the same reading must be displayed on the screen and then OL again. If this is the case, then the capacitor is in order.
Capacitor test with a multimeter continuity tester
In many multimeter models, a continuity tester with a diode test is integrated. This can also be used to test a capacitor. In this way, however, it can only determine whether a capacitor is charged.
The current from the meter first flows into the capacitor until it is fully charged. Subsequently, the resistance measurement can be carried out. The display on display then shows a continuously increasing reading until the measuring range is left, and only one is displayed.
Continuity test with an acoustic signal
Multimeters that have a continuity tester with an audible signal provide the following feedback:
- Acoustic signal continuous or not at all means the capacitor is defective.
- Acoustic signal changes in volume or pitch mean the condenser is ok.
With both variants, the capacitor can only be examined for a short circuit, or the charging process can be checked. The exact capacity of a capacitor can be measured in this way, but not.
Also, it should be kept in mind that capacitors in the removed state may react differently than if they are installed in a circuit. For small capacitors in the pF or nF range, measurements are entirely meaningful. Still, for larger capacitors over 10μF, it will be inaccurate, as they will behave differently under normal conditions during an analysis than under normal circumstances. Measuring capacitors in a circuit, but that’s instead something for professionals and less for hobby electricians.
The capacity of condenser measure with a multimeter
If a multimeter is available, which has the capacity measurement function, a direct capacitance measurement can be performed on the capacitor or electrolytic capacitor (Elko). The procedure is as follows:
1. Expose condenser
Again, it is essential first to remove the capacitor to be tested entirely from the circuit. All contacts to the circuit must be removed, and the two poles of the capacitor must be made freely accessible.
2. Visually check the capacitor
Before the capacitance measurement is performed with the multimeter, the capacitor should be checked for damage. If the surface has small bumps, fine cracks, or even escaping liquids, this may indicate a defective capacitor.
3. Discharge capacitor
The next step is to make sure that the capacitor is completely discharged. To get all the residual current out of the condenser, it can be connected to a consumer. Again, for example, it is a light bulb to discharge the energy from the capacitor completely.
4. Set the multimeter
Now the multimeter should be set to Capacitance Measurement (Farad readings). The measuring range is usually adjusted automatically by the device here.
5. Measure capacitance of the capacitor with a multimeter
Now both test leads can be connected to the poles of the capacitor. The display of the multimeter should now display a reading that is approximately equal to the value indicated on the capacitor. If both appraisals are very similar, then the capacitor is in good condition. If the measured value is significantly lower than the amount stated on the condenser or if no measured value is displayed at all, the capacitor is defective and must be replaced.
General note
Since capacitors or electrolytic capacitor (ELCO) store electrical current, they must be completely discharged before you can test the condenser with the multimeter.
With simple multimeters, you can only determine if a capacitor has a short circuit or if it is being charged. Exact measurements of the capacitance of a capacitor can solely be determined with appropriately equipped measuring instruments. In the multimeter test, you will find the suitable devices to test a capacitor with a multimeter.
Leave a Reply