MESR-100 "in circuit" ESR meter

[MarkMLl]

I know these have been discussed before, but I've bought myself one of the cheap ESR meters to help re-cap a monitor and thought a note might be in order.

https://www.aliexpress.com/item/4001224736909.html

The MESR-100 specifically describes itself as using a low voltage signal, making it suitable for in-circuit investigation:

Accuracy: Up to 1% (detail on above table)
Wide Measurement Range: >1uF
High Resolution: 4 digit, or 0.001Ohm @ 1 Ω range
Measuring voltage: <～40mV RMS (TESTING VOLTAGE)

It has a USB connection for power but I don't believe it has any logging/capture capability.

Open circuit, the test signal is roughly sinusoidal with about 0.4V peak-to-peak at about 170Hz.

Across a new 220uF 50V cap, the signal is somewhat more triangular and reduces to around 4.4mV peak-to-peak at about 115Hz.

Both of the above are auto-ranged, I've not investigated manual mode/range selection.

I believe I saw discussion of one of these meters while I was shopping around, possibly on Hackaday, which emphasised that they really didn't like being given longer leads. TBH, since they're going to be used on deenergised equipment and usually flat on the bench I don't see the length as being a problem, I would however be tempted to replace the supplied crocodile clips with copper stubs which could be attached with a deft dab of solder: doing that would result in a good connection but would still be much easier and potentially less destructive than removing every cap for testing.

MarkMLl

[kripton2035]

as it is a 2 wires measurment device, I'm pretty sure the 1mΩ resolution is not granted. at most 10mΩ and may be 20mΩ...
sorry but for me as of today the best available esr meter stays the jay_diddy_b esr meter adapter on this same forum

https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/

I build an integrated version with a led display you can se in the thread
https://www.eevblog.com/forum/projects/esr-meter-adapter-design-and-construction/msg2976938/#msg2976938

I'm currently rebuilding it using another method, as I have some difficulties to keep the zero reading with my display.
will certainly be a clone of the shorty-with-display you can see below, but for AC ohms.

[MarkMLl]

as it is a 2 wires measurment device, I'm pretty sure the 1mΩ resolution is not granted. at most 10mΩ and may be 20mΩ...
sorry but for me as of today the best available esr meter stays the jay_diddy_b esr meter adapter on this same forum

No apology needed, I assure you. I thought the FFTs of the signal might be of interest, but the thing I wanted to get into the record (as far as Google et al. are concerned) was the voltage: the MESR-100 looks like it might be half-decent for in-circuit use while there's another cheap one (badged as e.g. DTU-1701) which implies that it can be used for that but actually tests at around 5V.

The bottom line is that the MESR-100 confirmed that a cap which didn't look properly seated was actually dud, and I didn't have to unsolder anything that didn't get changed.

MarkMLl

[archil]

need this esr meter 

[Shock]

The downsides of the MESR is it might not be the best option if you want to use your own tweezers or prob leads due to zeroing problems. A tear down done a few years back showed a through hole cap and the sockets wires just tacked to the PCB. This along with the case and display made it no for me.

The Bob Parker designs (though it has 10 milliohm resolution) such as Altronics, Blue, EVB for me are the best bang for buck with flexibly for DIY leads and input protection, super easy to use as well. The JDB design has the most potential for a diy solution.