Won't read capacitors - GW Instek GDM-8431

[Obba41]

Hi all,
I bought a used GDM-8341 from Alibaba a few months ago. They showed me a video of the unit being calibrated and said it was in perfect working order.
It arrived in absolute mint condition, like new!

However, and I am a novice and this was my first desktop DMM. It does not read capacitors, just goes to OL.

I push the cap sign button, It is on Auto and when I put a 470nf cap on the leads, it comes up with a number that is nowhere near the cap value and a small dot going from left to right. The 5nf, 50nf and 500nf Auto stuff rotates and then the screen shows OL, and stays on that.


I have a Fluke DMM and the reading of the cap is immediate and dead on. But the Fluke uses battery's and I wanted a permanent on, easy to read DMM.

What am I doing wrong?

Many thanks,
Obba41.

[wraper]

I push the cap sign button, It is on Auto and when I put a 470nf cap on the leads, it comes up with a number that is nowhere near the cap value and a small dot going from left to right. The 5nf, 50nf and 500nf Auto stuff rotates and then the screen shows OL, and stays on that.

Are you sure you're actually selecting a capacitance mode and not a diode mode instead?

[Obba41]

Hi Wraper,
Yeah, I'm not that much of a noobie...

When in Diode more, it says Diode on the screen.

I might do a small video and post it on Youtube so people can see what its doing...

I have a OWON XDM1041 (but never use it, as its screen goes off now and again), and that takes AGES!! (like 30secs), to read the cap - I assume it's charging the cap up to give a final reading. I thought that the GDM-8431 might be doing the same thing, but no.
And it's a brand new bog standard 470nf 16v cap.

[Obba41]

Ok.
Did a Youtube video, I think LOL!
Please 'anyone' confirm that the link works...

A minute and half long.

It's a brand new 10v 470bf Cap.



I'm hoping that I'm not going to make an idiot out of myself. But I am new to using these fancy desktop DMM's.

Thanks,
Obba41.

[Jeroen3]

Your video is private.

Do you need to manually set the range for capacitance mode?

GW Instek makes nice stuff, but sometimes they work a bit odd.

[Kleinstein]

And it's a brand new bog standard 470nf 16v cap.

Class 2 ceramics (e.g. X7R and similar) and electrolytic capacitors are not good to compare different meters. They have high loss and nonlinearity, that can confuse especially DMMs that measure the capacitance in a bit odd way and with a not so well defined frequency. With the high loss the capacity is quite frequency dependent and this alone can cause 10% difference between meters.

For a comparison one should use film capacitors.

With open inputs there meter should still read near zero capacitance. For the smaller ranges one may have to use the rel. function (with already the cables). A wrong rel. value (done with a short) could cause issues.

[Obba41]

Oh, doh!

The video is now NOT private and I have made it PUBLIC.

[Obba41]

Well, people...
I have been a dummy. Idiot.
I hope that my mistake is a lesson to other people wanting to have a desktop DMM.

In my wanting to learn electronics and have no guidance besides this forum and YT. I have made a big expensive mistake.

In my video, I am trying to test a 10v 470uf capacitor.

The GDM-8431 only - that's - ONLY -goes up to 50uf.

In all my noobie research on buying a Desktop DMM, I must have missed the most basics of basics and not read/understood the area of what this DMM can handle.

So all my apologies people. My mistake.

Now I need to find a Desktop DMM that covers Caps range that I need and I might add that the GDM-8431 is a great DMM - in everything else I need, but not in the caps range I need.

All good fun at the end of the day eh?

Cheers,
Obba41.

[wraper]

Now I need to find a Desktop DMM that covers Caps range that I need and I might add that the GDM-8431 is a great DMM - in everything else I need, but not in the caps range I need.

You do not need that, measuring capacitance of electrolytic capacitors is one of the most useless things you can do to test them. Measuring ESR is an order of magnitude informative test of their state. Electrolytic capacitors that no lower work in the device can easily show capacitance that's within spec. And you can do that within circuit with no need to desolder them too. So get an LCR meter or ESR meter if you want to test those.

[OldBeginner]

It is possible to expand the measurement range by connecting the capacitor being tested through an additional series