How to Test Capacitor Without Desoldering (Easy Check)

Most of the time, electricians, hobbyists, and enthusiasts find themselves working with circuit boards.

These are the foundation of all electronic devices we see in the market, and ones that we make ourselves.

Circuit boards consist of a lot of different components such as capacitors, resistors, inductors, IC’s, and conductors, just to name a few.

It isn’t uncommon for one or a couple of these components to burn out or get damaged, which means they will have to be replaced.

With certain components like resistors and IC’s, figuring out whether or not they are functional is really easy and can be accomplished in a matter of seconds.

When it comes to capacitors, however, it gets a bit more complicated.

If you’re lucky, you can spot a faulty capacitor by checking its top, and if it’s busted open, that means the capacitor needs replacing.

That being said, a lot of times a normal-looking capacitor can still be faulty, which is why it’s highly recommended to test your capacitors to be sure.

A lot of people, especially beginners think that this requires desoldering, but you can actually test a capacitor without desoldering, which is what we’ll be talking about in this article.

So if you’ve been looking for a step-by-step guide to testing a capacitor without desoldering, you’ve come to the right place.

Read on to learn more.

How To Test Capacitors Without Desoldering

Unlike with other electrical components, you can’t test a capacitor with a simple multimeter.

This is because using devices like a multimeter or capacitor meter might actually read to inaccurate results.

This happens because capacitors inside a circuit are in a series or parallel to other components, so you actually get an equivalent reading, not an actual one.

While capacitor meters and multimers can definitely measure capacitance, they are not recommended for testing whether or not a capacitor is working.

Instead, there are a series of devices you can use to test a capacitor without desoldering such as an ESR meter, smart tweezers, and conducting an eye test.

In this section, we’ll be guiding you through how to use either of these three methods.

Check Using An ESR Meter (A Good Way to Test Capacitors)

Discharge The Capacitor

This is the most important step that you have to take when testing capacitors, regardless of what instruments are being used.

This is because not discharging it before testing might lead to you damaging the ESR meter or whatever tool you’re using.

This will have to be done regardless of what parameters are being tested.

To discharge, simply short the legs through any means you have available.

However, it’s recommended to use a high resistance wire when doing this.

And once you accomplish that, you can now move on to the next step.

Turn On The ESR Meter

To start testing, simply turn on the ESR meter until you get a “0” reading on the screen.

Once it has a 0 reading, that means you don’t have to shorten the leads and you can start testing.

Attach The Leads

To begin testing, all you have to do is attach the leads to the right places.

The tester has two leads, one red one and one black one.

The red lead gets attached to the positive terminal while the black one gets attached to the negative terminal of the capacitor.

Read & Interpret The Data

After you’ve attached the leads, the ESR meter should begin showing you data.

Simply take note of the reading then compare it to the table that is usually given on the body of the ESR meter to interpret it.

While most meters will already have the table printed on the body, other models won’t have this.

And in this situation, all you have to do is use the capacitor datasheet and compare it to the ESR value.

All capacitor datasheets will have their ESR value listed at a frequency of 100kHz and its specific voltage rating.

Any deviation from this frequency is an indication of a bad capacitor that needs replacing and

values will usually deviate upwards when it comes to capacitors.

Testing Using Smart Tweezers (Another Good One For Measuring)

While an ESR tester would be good enough to measure and test the ESR values of most capacitors, things can get pretty tricky when dealing with SMD components.

When it comes to flexibility and efficiency, smart tweezers may actually be the better option when compared to ESR testers.

They will allow you to get data and test SMD components as well as normal pin-hole components much easier.

That being said, a pair of smart tweezers can be very expensive, especially when compared to the simple and cost-effective ESR tester.

Smart tweezers on the market can cost as much as $300, which may be out of reach for a lot of beginners and hobbyists, and if that’s the case, an ESR tester is your best bet.

And if you do decide to invest in smart tweezers, it will still be a very worthwhile investment as it is a very useful and functional tool to have in the workplace.

To use smart tweezers to test capacitors, simply follow the same steps as when using an ESR tester.

Discharge the capacitor, attach the leads, and compare and interpret the data.

It doesn’t get much simpler and easier than that.

Checking It With Your Eyes (A Quick Way to Examine Capacitors Without Desoldering)

What a lot of people don’t know is that, in the absence of an ESR tester or smart tweezers, you can still check if a capacitor is working by conducting an eye test.

This is not the most accurate way to do it, but it is a quick, cheap, and easy way to get the job done.

A faulty or malfunctioning capacitor will bulge or swell on the top side, and if you notice this, then it means that you have a bad capacitor and it needs to be replaced.

Again, this is not the most accurate way to know if your capacitor is bad, but it is a quick and easy way to check.

When in doubt, it’s always best to use the proper tools and instruments for the job.

Do I Have To Remove It First?

How to test capacitor without desoldering

A lot of people think that to test a capacitor, you have to desolder and remove it from a circuit board.

This isn’t the case, as there are numerous ways that you can test a capacitor without desoldering.

The first method is to use an ESR meter, which only requires you to discharge the capacitor before testing.

You can also use the same techniques to test a capacitor with smart tweezers.

Once you get a data reading on the ESR value, use the table that is printed on the meter or read the capacitor data sheet to determine whether or not it’s faulty.

On top of that, you can conduct a quick eye test and see if the capacitor is swollen or has bulged towards the top.

If it has bulged, that is an indication that the capacitor is no good and needs to be replaced.

Can I Use A Multimeter To Test?

As we mentioned earlier, while a multimeter can be used to test a lot of different components but won’t be reliable for testing capacitors.

This is because while it can test for capacitance, the data will not be reliable.

The reason for this is that capacitors are usually in series or parallel with other components, which could get in the way of getting an accurate data reading.

That is why ESR testers and smart tweezers are more recommended for testing capacitors as compared to multimeters.

How Can You Tell If A Capacitor Is Shorted?

To test if your capacitor has shorted, you will need a multimeter.

Simply connect the leads of the multimeter to the capacitor and observe the data.

If the resistance meter starts at a low value and gradually increases, that is an indication that your capacitor is working just fine.

However, if the resistance stays low for a long time and doesn’t rise, that is an indication that you have a shorted capacitor that needs to be replaced.

What Happens When It Is Shorted?

When a capacitor gets shorted, resistance will be built between the voltage and ground wires.

This can potentially mess things up in a circuit, which can cause a lot of different issues.

So if your capacitor is shorted, make sure to change it right away to avoid any complications or causing any damage to your electronics.

On top of that, if a capacitor is shorted, the device simply won’t work at times.

How Do I Measure Voltage, Capacitance, And Other Variables Related to a Circuit Board?

There are a lot of tools that can help you achieve your goals when it comes to electronics and circuit boards.

You can check out our other guides here for more info.

Conclusion

And with that, our quick guide to testing capacitors without desoldering comes to an end.

There are many different ways you can do this, all using a variety of tools and instruments.

In fact, one of the methods only involves using your eyes and observational skills.

So now that you know how to do it, all that’s left for you to do is head to the workshop with whatever instruments you choose to use, and get to testing your capacitors!

Further reading:

How Capacitors Work

Last Updated on June 19, 2021 by Tom