I am trying to do a current measurement.

Probably I accidentally put it it parallel instead of in series.

What I tried before/after that (cannot remember exactly putting it parallel but might have happened likely) :

  • Used both connection with 10A and normal output on the multimeter.
  • Use all settings for current (200 mA, 20 mA, 2 mA, 200 uA)

I put it in series with a LED. When using the normal output the LED is off (open circuit), when using the 10A output the LED is on (closed circuit).

I get always 0.000 A (even when the LED is on and put it in series). Did I ruin my multimeter?

The ohmmeter and voltmeter still works.

Below a picture of my multimeter (found on internet, exactly similar):

enter image description here

  • 2
    \$\begingroup\$ Open it, check the fuse. \$\endgroup\$ – Dampmaskin Sep 3 '18 at 20:50
  • \$\begingroup\$ @Dampmaskin the display still works or are there more fuses inside? \$\endgroup\$ – Michel Keijzers Sep 3 '18 at 20:51
  • 1
    \$\begingroup\$ Yes, probably. Since your ohm meter still works, pull out the fuse and measure its resistance. \$\endgroup\$ – Dampmaskin Sep 3 '18 at 20:53
  • \$\begingroup\$ @TonyEErocketscientist I checked, only the 250 mA one is ruined. \$\endgroup\$ – Michel Keijzers Sep 3 '18 at 21:08

The current measurement circuit in a multimeter needs to be low impedance. That means it is possible to expose it to overcurrent. Actually it's quite easy: All you need to do is to put it on a voltage source with a little bit of oomph, with nothing to limit the current.

A very easy mistake to do, as you no doubt know by now.

Because of this, any multimeter worth its salt has a fuse on the current measurement circuit(s).

Since the volt- and ohm meter circuits are separate high impedance circuits, they don't need to be fused, and will likely still work, even if you blow the current fuse(s).

This means that you can pull the fuse(s) out and measure them with the ohm meter on the same multimeter. A good fuse should have very low resistance, a blown fuse should have infinite.

When replacing the fuse(s), get good quality ones. They should be filled with sand, so that they don't explode if you accidentally short (e.g. try to measure the current across) the mains or other high energy sources.

Here is a text from Fluke explaining why using quality fuses is important.

  • \$\begingroup\$ It's exactly as you described ... I only have a glass fuse here, and checked on internet (AliExpress) there is no sand fuse under for 250 mA (starting from 1A only) or very high priced (like 50% of the value of my multimeter). Maybe a stupid question, but if explosion is a problem (and making a mess inside the multimeter), can I put isolation tape around it to prevent it until I find somewhere a better sand fuse? \$\endgroup\$ – Michel Keijzers Sep 3 '18 at 21:12
  • \$\begingroup\$ (I guess they are also called ceramic fuse?) \$\endgroup\$ – Michel Keijzers Sep 3 '18 at 21:20
  • 1
    \$\begingroup\$ Tape won't help with the plasma, and I don't feel qualified to give safety related advice, but read the Fluke article and maybe the following thread. That ought to give you a handful of search keywords to continue your research. eevblog.com/forum/testgear/multimeter-fuses \$\endgroup\$ – Dampmaskin Sep 3 '18 at 21:26
  • \$\begingroup\$ I found ceramic fuses, only 200 mA or 500 mA (or bigger), guess 200 mA is safer to use. \$\endgroup\$ – Michel Keijzers Sep 3 '18 at 21:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.