# Is my multimeter fuse blown? [closed]

This is the only multimeter I have. I do not want to buy a new one to test one I already have. I know when a fuse is blown when the fuse is clear. This fuse is white. Not clear. My multimeter is not working even though I replaced the batteries. I think the fuse might be blown. I don't know since I have not used the multimeter in a long time. I tried searching it but I could only find information on clear ones. Not white ones. This is a 50 volt fuse.

• You have a DMM ... use to test the fuse – Tony Stewart EE75 Mar 12 '18 at 3:01
• Test it in ohms mode. If it says 0 ohms (or close to) it's not blown, if it says infinite ohms it's blown. If you don't know whether your resistance mode is still working, then tap the leads together and make sure it says 0 ohms. – user253751 Mar 12 '18 at 3:54
• put a piece of wire into the fuse holder temporarily to see if the DMM powers up .... if it does, get a new fuse .... do not run it with the wire installed .... btw: fuses are rated by current in amps Aand milliampsmA ... the voltage rating is the maximum voltage that the fuse will protect against when blown (it may arc above the rated voltage) – jsotola Mar 12 '18 at 5:00
• Looks like a picture that was taken from 300000 km distance with the fuse being on the moon. Conspiracy theorists would argue its an UFO. – Rev Mar 12 '18 at 11:05

A fuse in a DMM is usually included into current measuring path only. It shouldn't affect operations of voltmeter mode or ohmmeter mode. You should be able check the fuse continuity with your blown-fuse DMM. If your DMM isn't showing any readings after installing fresh batteries, you have a bigger problem than just a fuse.

• some multimters have the fuse when measuring volts and ohms, some don't. it mainly seems to be the cheap ones that have the fuse for all features, the better multimeters are designed to be safe without the fuse when measuring volts and ohms. – Jasen Mar 12 '18 at 8:19
• Thank you for sharing this. My multimeter is broken. Or at least the little needle won't move when I touch the two ends, they are pluged in, and it is turned on. – ProfessorX234 Mar 13 '18 at 2:04

From the photo, what you have is a ceramic fuse. Always replace it with the exact type and rating for continued protection. Glass fuses, even if marked with the same voltage and current ratings, do not provide equivalent protection.

The only way to test the fuse by itself is by passing current through it. One way is to get a 9V (PP3) battery, a resistor and an LED. A few K for the resistor is fine, say 1-10K. Eg.

(Sorry, the photo is a bit blurry)

Try making a makeshift continuity tester using a battery torch/flashlight. Open up the back as if you are replacing the battery. Using a bit of wire, link across the back of the flashlight between the negative terminal of the battery and the body of the flashlight, or the metal strip inside if it's a plastic body. Check that it lights.

Now try it again, adding the fuse. Link the body of the flashlight to one end of the fuse with the wire, and press the other end of the fuse against the battery. If it lights, the fuse is OK.