Signstek MESR-100 V2 ESR Meter, Capacitor Tester/Low Ohm Meter 0.01R-100R

The MESR-100 may not look flashy compared to modern touchscreen test equipment, but it has earned a permanent place on my electronics bench. This is one of those classic tools that does a specific job very well, and if you work on electronics repairs, it's incredibly useful. The primary reason I use it is for troubleshooting capacitors. A capacitor can look perfectly fine and even measure close to its rated capacitance, yet still have excessive ESR that causes a circuit to malfunction. The MESR-100 makes it quick and easy to identify those problem components without a lot of guesswork. I've used it on power supplies, consumer electronics, and various repair projects where tracking down a failing capacitor would have been much more difficult with a standard multimeter alone. One of the best features is the ability to perform many measurements in-circuit. Instead of desoldering every suspect capacitor, I can often get a good indication of component health directly on the board. That saves a tremendous amount of time when troubleshooting. I also use it when selecting replacement components. When comparing capacitors from different manufacturers or evaluating parts from my component inventory, it's nice to have an easy way to check ESR and resistance characteristics before installation. It provides an additional level of confidence that the parts going into a repair or project are actually suitable for the job. Operation is refreshingly simple. There are no complicated menus or lengthy setup procedures. Turn it on, connect the probes, and start measuring. The auto-ranging works well, readings are easy to interpret, and the instrument does exactly what it was designed to do. While I own more advanced test equipment, the MESR-100 remains one of the tools I reach for most often during repair work. It's a classic piece of bench equipment that has stood the test of time because it solves a real problem quickly and effectively. If you repair electronics, troubleshoot circuit boards, refurbish equipment, or simply want a better way to evaluate capacitors, this meter is absolutely worth having. Simple, reliable, and extremely useful.

What Makes It So Useful (For Real Work) The biggest win for me is in-circuit ESR testing. I don’t have to desolder every capacitor just to check if it’s bad. I can probe directly on the board and get a solid answer in seconds. That alone saves a ton of time. It uses a ~100kHz test signal, which is important because it matches how capacitor ESR is actually measured in real applications . Why I Trust It More Than a Multimeter A regular multimeter might tell me capacitance—but that doesn’t tell the full story. This meter shows ESR (internal resistance), which is usually what actually fails in caps over time. Low ESR → good cap High ESR → bad cap (even if capacitance looks fine) That’s huge when troubleshooting unstable power supplies. Where It Helped Me Most I’ve used it for: Xbox PSU repairs (huge here) Motherboards and GPUs Old TVs / monitors Random SMPS boards It’s especially useful when I’m chasing intermittent issues or unstable voltage rails. Fast, Simple, and Repeatable No menus, no complicated setup: Touch probes → instant reading Auto-ranging handles everything Built-in ESR chart helps quick comparison It measures roughly 0.01–100Ω, which covers most real-world capacitor failures

Works well to identify defective capacitors. As many people have said, the leads are not just too short, they are tied to close to one another. The leads need another 4" and the separation needs to be another 2" to be able to get to awkward connections.

Worth easy battery life is good

I do electronics repair as a second job. This is a great tool for troubleshooting and saves me a lot of time. Bad capacitors are a frequent problem but they are difficult to test and I don't have the time to just replace every capacitor I run across on finicky equipment. PROs: Tests capacitors better than a multimeter without having to desolder them. Posts the results in plain English as well as the numeric readings. It's reliable. I have tested quite a few capacitors so far and the results so far are accurate and repeatable. It's inexpensive. I shopped around for a quality ESR and found that units typically cost more than this, have to ship from China or Russia, and frequently don't have as many features. CONSs: The battery door is difficult to get to. The stand is in the way. It's a minor hassle. I plan to just remove the stand entirely as I do not use it. It's not extremely precise, particularly on small capacitors. Caps below a certain point you have to look up on a table (which is handily printed on the unit). The numbers can vary a little but not enough to make a difference for what I'm testing. All I want to know is the answer to one question: "Is this a good cap?" It's precise enough to be accurate in answering this question and that is all I care about.

I'm am amateur at repairing circuits, but this device is great for testing capacitors in circuit which is very helpful. I've already repaired a few devices with it by finding bad caps. The only tricky issue with this tester are the short leads which others have pointed out, but that is due to it being so sensitive that the leads must be short for it to work. You can snip off a short piece of wire and put in each alligator clip to make the test leads a little more useful for getting in hard to reach areas. Overall this tester is a must have for doing any circuit repair, especially looking for bad caps.

I have many pieces of electronics that stopped working. Sound Bar, Electronic Whoopers, Sirens used in security protection systems plus a number of others. I don't have the time to spend diagnosing their problems because it is much simpler and faster to just go out and buy another one. One day while watching a You Tube video on electronics repairing for the non-professional, the host was demonstrating the use of this Signstek MESR-100 Ver2 ESR Meter with in-circuit testing. He stated that quite often that electronic equipment fails or failed because electrolytic capacitors were the culprit and this meter can check each capacitor in-circuit - which means I wouldn't have to remove each one to check it. Wow, my first impression was now I can repair the above quickly and save money in the process. Well, I didn't find (not one) failing or failed capacitor. OK, I must admit the cables are far to SHORT in length. I was dragging the meter all over the circuit boards attempting to check each capacitor. Each time I would finally make contact with (cable probes to a capacitor) the short cables turned the meter upside down or on its side to prevent me from seeing the display which would define information I need to determine if the capacitor was good or bad. This occurred too many times at which I promptly put the meter and cables back in the box and put it away. The cables make testing electrolytic capacitors a "NIGHTMARE" in circuit. Testing out of circuit is just fine and the meter tested every good electrolytic capacitor I had correctly. So, if the cables were longer this meter would probably warrant a five. Again, the meter appears to be a "near professional instrument" except for the cables which defeats the whole purpose of using it... in-circuit. Also, I believe the instructions have a statement to not substitute the cables supplied with longer ones. I am hoping either the manufacturer or a professional electronic technician will offer a solution for longer cables that would make this meter an excellent tool for diagnosing bad electrolytic capacitors in-circuit.

This device has truly simplified the task of testing capacitors that are part of a circuit. It's the go-to solution if you don't want to go through the hassle of desoldering components just to perform a basic capacitor check. The auto-ranging feature is a lifesaver, making it incredibly easy to measure the Equivalent Series Resistance (ESR) and inductance (LCR) of capacitors while they're still soldered in. This is a game-changer for troubleshooting circuits and identifying faulty capacitors quickly and efficiently. Gone are the days of traditional, time-consuming desoldering and testing methods. The Signstek offers precision and convenience in one package, making it an invaluable tool for electronics enthusiasts and professionals. It has truly revolutionized the way we diagnose and maintain circuits, sparing us from the painstaking desoldering process. If you work with electronics and need to test capacitors in-circuit, this meter is a game-changer.

Love this thing, but the leads slip around when trying to clamp them and they are very short they should be longer and have the ability to put tiny probes on as well!!