Is this multimeter broken?

[sander]

Hi all,

Going to start delving into the car's electricals soon, so I'm doing a crash course with a new digital multimeter. Decided to get a cheap one to learn the basics on before looking for something better, but I may be paying for my thriftiness...

So I did a little tutorial and the DMM was reading voltage, amps, and ohms just fine. But somewhere along the line something seemed to happen to the Ohmmeter.

And now anytime it's in ohmmeter mode, it basically goes into a "countdown" and the numbers just decrease steadily and even go into negative numbers.

This even happens when I simply touch the two leads together - which should be a calibration test for resistance, correct? That should just read zero (or close to it).

This DMM doesn't have any kind of calibration for ohms (as far as I can see). So is this one really just fried as far as its ohmmeter, or is there something I'm missing here...?

Thanks!

[1990C4S]

Sounds like it's toasted. It should read infinite resistance when the leads are not touching each other, and pretty close to zero when they are touching.

Measuring Amps isn't for beginners. Not saying that's how it got damaged, but it's a possibility.

[sander]

Thanks, yeah I'm pretty sure I toasted it somehow

This is pretty much exactly why I got a cheap one to learn on, so maybe that strategy actually paid off in the end. Guess I can still use this one for other measurements in the meantime...

[JerryL]

Dont know the model but most have a fuse inside with the element about the size of a hair, may check it, most places that sell a multi meter have the fuses including Lowes & HD
Give it a shot what is another $1.00

Regards

[sander]

Thanks Jerry, I actually realized that as well and just checked - and indeed, the fuse is blown. I'll replace that first and see what happens...

[Joe Bob]

Buy a used Fluke.....or new. Idjut proof.

[sander]

Just for the sake of those who like Closure - popped in a new fuse and we're back in business...

[911pcars]

Originally Posted by Joe Bob

Buy a used Fluke.....or new. Idjut proof.

Idjut proof. No. Ask me how I know.

The advantage of an inexpensive multimeter is the inexpensive internal fuse ($1).

The disadvantage of a more expensive multimeter (e.g. Fluke) is the expensive internal fuse ($10-$15).

Sherwood

[T77911S]

i would, and do, use a test light. it is easier to use and you dont have to worry about breaking a $300 MM.
when you are upside down under dash, what is easier, tryiing to read a MM or just see the light in the test light light?
go to any auto electrical shop, unless they need an actual voltage, they are using a test light.

[Neel]

A very simple solution is to wire an inline fuse into one of the leads of the multimeter.. This way you avoid the expense and time of replacing the meter's internal fuse.. I did this with all the multimeters I used when teaching multimeter useage to students.. Also, even experienced users can forget to swap leads around sometimes..
Test lights.. If you must use a test light, buy one that has high impedence.. A regular test light plugged into a computer circuit can cause more damage than the cost of a good multimeter..

[dad911]

Originally Posted by T77911S

i would, and do, use a test light. it is easier to use and you dont have to worry about breaking a $300 MM.
when you are upside down under dash, what is easier, tryiing to read a MM or just see the light in the test light light?
go to any auto electrical shop, unless they need an actual voltage, they are using a test light.

+1. Most of the time 2 test lights will do the job. Continuity light (built in battery) and a test light.

Don't ever use ohm (resistance) settings on a live circuit. Be very careful measuring current. For current measurements, meter goes in-line (in the circuit) unless you have a clamp-on meter(which I recommend)

[911pcars]

Originally Posted by Neel

........Test lights.. If you must use a test light, buy one that has high impedence.. A regular test light plugged into a computer circuit can cause more damage than the cost of a good multimeter..

Some folks insist on using a regular test light (incandescent bulb) to troubleshoot. That's fine if there isn't a low-voltage ECU within sight. Potential is high to let smoke out of the system in the hands of an inexperienced tech.

OTOH, a high-impedance LED test light is pretty safe, with some caveats:
TechOne: Basic automotive service ... - Google Books

Sherwood

[HawgRyder]

The reason the fuse was blown....you had it on "Ohms" when you checked a live circuit.
It's a common mistake with new users...and some old ones too.
The fuse protects the resistance circuit.
Replace the fuse....make sure the circuit is dead before checking resistance...and have fun.
Bob