How to use ESR meter (Using MESR-100, 2024)

The answer to the question, of how to use ESR meter, is really simple and straightforward. Connect the capacitor to the meter, note the reading, and compare it with the given ESR table to tell if you have a bad capacitor or a good one.

The above is a short summary, of course. You can consider this as a general rule of thumb for all the variations of available ESR meters.

ESR value is an important parameter of a capacitor. Using this value we can actually tell if the capacitor is good or bad even without desoldering it from the PCB board, thus saving us a lot of resources.

If this introduction got your attention, then I am pretty positive you will enjoy the rest of this article as well.

Hi, I am Abbas. In the rest of the article, I will explain in detail what is ESR meter is, how to use an ESR meter the correct way, how to find out the bad cap from the good one, and so much more.

I am not perfect, nor is this article going to be. This is just my limited knowledge try to help you somehow.

I hope you will enjoy it.

Table of Contents

What is an ESR meter

The word ESR stands for equivalent series resistance. Now the device that measures this value is called an ESR meter, pretty simple right?

An ESR meter is a very special tool when it comes to testing a capacitor. We use a multimeter for testing capacitors as well but an ESR meter help to test a capacitor even when it is in the circuit board.

How to use ESR meter (MESR-100) — MESR 100

The above is the MESR-100. This is the best ESR meter on the market according to my opinion.

By looking at this device you can say that it is a simple device. It has three operation buttons, two ports for probes, and a wide digital screen for reading.

If you pay close attention to the port there is a dotted line. These dots are the slots where you put your capacitor under test for reading if you don’t want to use the probe cables.

The beauty of this ESR meter is you can power it up using two options. One is a battery and the other is a USB adapter. It is up to you which option you prefer.

The above device is specific to the ESR reading. You will see other devices as well available on the market. You will find multimeters and LCR meters with ESR value measuring capabilities. It doesn’t matter what tool you prefer, just remember the purpose of the ESR meter is to test a bad capacitor in or off the circuit.

How to use ESR meter (taking the example of MESR-100)

This is the question we really need to answer in this article. The above was the background building so that, so you have a clear idea of what is an ESR and why it is important to measure.

Let’s see how to use ESR meters of any shape and variation. As there are many ESR meters available on the market. I will first explain a general method applicable to all meters. Then I will share the exact method for MESR -100 ESR meter. Because this tool is widely used in the field.

General method

In general (how to use ESR meter), you will find the ESR feature in mostly LCR meters and most often in advanced multimeters. The following is the most used LCR meter (DE-500) on the market.

This is the DE-500 ESR meter (Amazon link). If you pay close attention to its operation buttons you will find an ESR button. This will be true for all ESR meters and multimeters. Just search for the ESR button or functions.

After you find the ESR button follow the following steps:

Press the ESR button so that you get into the ESR mode
Take the capacitor you want to test and completely discharge it first.
Connect the probes in the right polarity if the capacitor is electrolytic.
Note the reading on the screen, it is that simple

Make sure you connected the probes correctly and your capacitor is completely discharged. In case you connect a fully charged capacitor by accident. This may result in damaging your LCR meter.

Measuring ESR with MESR-100

Now the same steps of how to use ESR meter apply to this guy as well. But let’s see them in detail. For this method, you should have MESR-100 (Amazon link) in your lab. If you are into repair I think this meter will save you a lot of time.

Follow the following steps to use MESR-100:

Turn on the meter and see the value on the screen. This value should be ideally zero, but generally, it should be close to zero.
Connect the probes first in their right ports
Now if the value were not zero at the beginning. Then short the probes and see the value decreasing to zero.
When we confirm that the value on the screen is zero. It is time to go for the next steps.
Discharge the capacitor completely with a high resistance tool available to you.
For an electrolytic capacitor connect the negative probe to the negative terminal of the capacitor and the positive to the positive – this is very important.
Press the test button
See the results on the screen

The value you see on the screen is the ESR value of the capacitor. Note it down. It is time to see if the capacitor is a good one or a bad one.

The above was the steps of how to use ESR meter. They are simple once you practice them repeatedly.

How to tell if the cap is bad

As I have shared a few times the ESR value is used to test a bad capacitor.

Now the whole point is, that an ideal capacitor has an ESR value equal to zero, but in reality, it is very less; close to the ideal zero value. A high ESR value is the first indicator of a capacitor’s failure.

Every capacitor has its rated ESR value given in its datasheet for reference. We used the above tool to measure that ESR value.

To tell if the capacitor is bad we just need to compare the measured value with the given datasheet value. If the value drifted by 10% then it would mean that we have a bad capacitor.

Checking by MESR-100

Checking a bad capacitor with MESR-100 is very easy. It has given a table of ESR values on its body as you can see it yourself in the above given picture.

All we need to do is take the reading and compare it with the given table. And furthermore. On the screen, you will also get the indication that the capacitor is bad without even comparing and looking for the ESR values of that particular capacitor.

Conclusion

The ESR value is an important value to measure. It helps us find out the bad capacitor even in the circuit boards. To measure this value we need to have a decent ESR meter.

There are so many ESR meters out there on the market. Choose whatever you like. All the meters will help you measure the ESR of any electrolytic or ceramic capacitor of any value and rating.

After picking the meter it is time to learn how to use ESR meter. Every ESR meter is different, but there is a general way to use any ESR meter which I shared in great detail in the above sections.

And well, there you have it. Now, if a reader like me, reads the conclusion first. You read it. It’s time to go to the beginning. But you are the reader, making this far. I hope you enjoyed it.

Thank you and have a grateful life.