Electronics > Beginners
LCR meter ESR measurement seems off - What am I doing wrong?
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Shock:
There might be a little more to this. https://www.ittsb.eu/forum/index.php?topic=343.0

I would expect to be able to zero the LCR meter on two wires.

When troubleshooting these things I always rule out the leads, make the most direct short possible i.e. the component lead socket, or a bridged double banana plug. Try and zero to see if any difference. It pays to measure several small resistances or even a length of wire can work, shorting directly across to see if you can take various consistent measurements that make sense. Do this before you get to measuring capacitors. You might also want to use new batteries as well.

You can use whatever length leads you like but be aware they do impact the measurement especially when precise measurements are required, this is why shorter the better is generally a rule. While you can't totally eliminate the length of the leads affect on the measurement even after zeroing, the meter should still be usable even with a set of full length DMM leads zeroed out, especially for "ball park" measurements.

Be warned the LCR meter has no input protection against charged caps so is not so suitable (in my opinion) for constant in-circuit testing.

This video demonstrates how to perform a quick consistent measurement test, even though it's 4 wire measurement (modified test hooks) the same principles apply.

jdurango:
Thanks for the info! I've got really good leads on my u1253b, it couldn't hurt to try zeroing them out and see how close they are to the little gators. I don't need mOhm accuracy....95% of the time I'm just checking ESR in vintage studio equipment and need to get a rough approximation of the viability of a lot of caps. Some mixing consoles have thousands of caps. It'd be really nice to be able to sniff out which one(s) might be bad without pulling all of them, then only pulling the ones which seem suspect for closer/more accurate insoection.

I realize you need to discharge all caps before doing this and be especially careful on valve gear, or better yet, just don't use this method on valve gear at all.
mr.fabe:
You can get the Keysight tweezers for your LCR meter.  It has a long lead. Costs around $35 or less in the U.S. But... the tips are huge and the stiff cable has the tendency to move the meter all around the place.

Sent from my Moto Z (2) using Tapatalk

jdurango:
Thanks! I think I'll just do that! I tried my u1253b leads on it today and after zeroing out, they work pretty well! A little jumpy/unstable and probably not good for super sensitive tight spec measurememts, but good enough for 99% of the work I'll be doing.

With this new power comes great responsibility. Thou shalt always discharge thine capacitors!
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