Testing capacitors is a key diagnostic step in electronics repair and troubleshooting. Whether you’re working on a power supply or an amplifier, knowing how to perform a multimeter capacitor test can save time and prevent equipment damage. This guide explains how to use a multimeter to check capacitors, whether your multimeter includes a capacitance function or not.
Table of Contents
How to Test a Capacitor with a Multimeter
To test a capacitor, begin by identifying whether your multimeter has capacitance testing functionality. If it does have this functionality, check that it can measure capacitance in the correct range for the capacitor under test.
Follow the appropriate method below: Method 1 below uses a multimeter with capacitance test functionality. This is followed by method 2 that uses a multimeter without capacitance test functionality.
Method 1: Using a Multimeter with Capacitance Testing
A multimeter that tests capacitors typically has a dedicated “capacitance” setting marked with a symbol like “μF” or with a capacitor symbol. The image below shows an example of a multimeter with a capacitance measuring capability. Note that the red lead has to go into the mA socket for the capacitance test and not the V socket for this particular multimeter. The capacitor symbol is shown on the dial and on the test lead socket.
Basic Testing Steps:
- Discharge the capacitor fully (short the leads with a resistor or use a discharge tool).
- Set the multimeter to the capacitance mode.
- Connect the multimeter probes to the capacitor terminals (polarity matters for electrolytics).
- Read the displayed value and compare it to the capacitor’s rated value. Bear in mind that some capacitors can have large tolerances, such as 20%. This means that the measured capacitance can be between the stated capacitance plus 20% and the stated capacitance minus 20%.
Multimeter Capacitor Test Example with Amprobe Meter
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Read the instruction manual for the particular make and model of multimeter that you have. The multimeter pictured in the previous image is an Amprobe 37XR-A model. It has the following instructions in the Measuring Capacitance section of its user manual:
- Set the Function Switch to the –| |– function.
- If RANGE is displayed, press the RANGE button to enable autoranging.
- Connect the Test Leads: Red to COM, Black to mA
- Turn off power to the circuit being measured.
- Discharge the capacitor using a 100 k ohm resistor.
- Free at least one end of the capacitor from the circuit.
- Connect the Test Probes across the capacitor. When measuring an electrolytic capacitor match the test lead polarity to the polarity of the capacitor.
- Read the display.
Further to the above, it has the following in the CAPACITANCE section of the Electrical Specifications in the user manual:
Ranges: 40nF, 400nF, 4uF, 400uF (3999 counts) (Auto/Manual ranging)
This shows that the meter has limitations on the range of capacitance that it can read. This particular meter can’t measure a 1000uF capacitor for example. Be aware of the measuring limitations of your own multimeter.
Multimeter Capacitor Test Example with Metex Meter
Some meters have a different way of connecting a capacitor for capacitance measurement. The following image shows a Metex multimeter that has dedicated slots for connecting a capacitor for measurement. This particular meter has fixed manual ranges that can be selected on the dial.
The disadvantage of this method of connecting a capacitor is that the capacitor must have long leads in order to fit into the slots on the multimeter and make a good connection with the contacts inside.
A small trimmer wheel to the right of the capacitor in the image below must be rotated to zero the capacitance reading on the multimeter before inserting a capacitor in the slots. This ensures that capacitance from the contacts and wiring in the meter is neutralized before measuring the capacitance of the capacitor under test.
Method 2: Using a Multimeter Without Capacitance Mode
You can still check a capacitor using a multimeter by measuring resistance.
Steps:
- Discharge the capacitor.
- Set the multimeter to the ohm (Ω) range.
- Connect the probes:
- A good capacitor shows a rising resistance (charging).
- A shorted capacitor shows zero or very low resistance.
- An open capacitor shows no resistance movement (infinite).
This method is often referred to as checking a capacitor with an ohm meter.
Understanding Different Multimeter Capacitor Test Results
| Test Method | Good Capacitor Sign | Bad Capacitor Sign |
|---|---|---|
| Capacitance (μF) mode | Reading close to rating | Far below rating or no reading |
| Resistance (Ω) mode | Rising resistance | Constant 0Ω or no movement |
Tips for a Multimeter Capacitor Test
- Always discharge capacitors before testing to avoid damage to your multimeter.
- Use auto-ranging multimeters when available for more accurate readings.
- For electrolytic capacitors, note the polarity before connecting probes.
- If readings seem off, check your multimeter’s battery or test leads.
- Test capacitors out of circuit for the most accurate results.
Did You Know About the Multimeter Capacitor Test?
- Early multimeters couldn’t test capacitance; it required standalone LCR meters.
- A multimeter capacitor test works best on capacitors above 1 μF. Very small capacitance values require more precise instruments.
- Some advanced multimeters can test equivalent series resistance (ESR), a key measure of capacitor health.
Frequently Asked Questions About the Multimeter Capacitor Test
How do I know if my multimeter can test capacitors?
Look for a setting labeled “μF” or “cap.” If your meter includes this, it’s a multimeter with capacitance testing capability.
Can I check a capacitor in-circuit?
You may get inaccurate readings due to parallel paths. For best results, remove the capacitor from the circuit.
What happens if I test a charged capacitor?
A charged capacitor can damage your multimeter or give false readings. Always discharge it safely before testing.
How to test a capacitor without removing it?
While not ideal, you can use a quick ohm meter test in-circuit, but results may be unreliable due to surrounding components.
How accurate is a multimeter for testing capacitors?
Most multimeters that test capacitors are accurate for general-purpose testing, but not as precise as dedicated LCR meters.
Can I test a ceramic capacitor with a multimeter?
Yes, but accuracy may vary. Ceramics under 1 nF often show no result on basic multimeters.
Conclusion on the Multimeter Capacitor Test
A multimeter capacitor test is a reliable way to check whether a capacitor is functioning correctly. Whether you’re using a basic multimeter to check a capacitor through resistance or a model with capacitance measurement, understanding the process ensures accurate diagnostics.
Always discharge capacitors before testing and, when possible, compare values to the manufacturer’s rating. Mastering this simple test can greatly enhance your electronics troubleshooting skills.
If you’re ready to continue testing components, learn how to check diodes with your meter by reading our guide on how to perform a diode test using a multimeter.
Read more on capacitors for beginners on our companion website.