Electronic – Have I broken the Multimeter

currentmultimeterprobesparkvoltage

Firstly, I'll answer my own question by saying that I don't think I have broken it.

However, is it possible I could have? (and also possibly, the power supply I was testing).

I am quite new to electronics and recently purchased a Fluke 115. Having watched a few YouTube videos and looking through its manual, I decided to measure Voltage (V) and Current (A) between a DC power supply and a Mini-ITX motherboard.

So, I Connected the black lead to the common terminal, and the red lead to the V terminal. Stuck the ends of the probes on the outside and inside of the barrel jack. Set it to Volts DC. Measuring voltage fine with normal/reverse polarity. (+/-).

Now I went to try and measure current… sigh…

Using a lead I made with a Mini-fit JR connector on one end, and a soldered DC jack on the other, I snipped the positive wire so I could break the circuit and put the probes in-line. I fitted some crocodile clip accessories from Fluke to the probes, set it to Amps DC and tried measuring. I was getting a zero reading, so I must have done something wrong?

Stupidly, I thought, hmm… I will just double check the meter is still working and tried to measure volts again. Took the croc-clips off, stuck the probes in the jack and pop/flash, a spark appeared. Pulled away quickly.

I had left the red lead in the A terminal 🙁

Here is why I don't think I've broken it (or the power supply):

  • Firstly, I did a fuse check by connecting one probe to the V
    terminal, and putting its probe into the A terminal. Setting it to
    Ohms, it gave me a reading of 0.1/0.2 Ohms. So the fuse doesn't appear to be blown.

  • After actually connecting the probes in the correct way, I am getting
    the correct Voltage still.

  • Also I figured out why the current wasn't working, and I'm now
    getting an acceptable reading of Amps.

Some additional info:

  • The power supply outputs 19V, and can supply up to 6.32A.

  • Inspecting my probes, and the black probe where the spark came from has a tiny
    little dark patch (very very small).

I normally wouldn't care, but the meter was expensive with it being a Fluke, but I wanted something accurate.
I also don't take chances with anything electrical due to possible shock/fire risks.

Then again, I realise I am an idiot for quickly rushing ahead and measuring things.

But, do you think I've broken anything?

Best Answer

Your meter is most probably not broken. Check for an internal fuse, usually conspicuously placed and replace it with a similar fuse with a rating no higher than the original. Also, if your power supply is not working, check that for a blown output fuse. Good luck!