WTF did I do to my multimeter?

[Feydd]

OK I have this analog multimeter I built myself in an EET class. Yesterday I was messing around with it trying to measure the amps in one of those battery packs that plugs into a cordless phone. I noticed while I was doing this a small spark was being generated between the two test leads. So I go try to measure something else to see if I messed something up. Now the thing won't measure anything. No volts, ohms, or amps. I took the cover off to check if I blew the fuse but the fuse is fine. Any clues as to how I should go about fixing it?

This is one of the first electronic devices I built by hand and don't want it going in the trash so soon.

 

[four4875]

look for burnt resistors? or other components? might have sent too much to the gauge's coil and burnt that up

 

[GigaForce310]

Check resistances with a digital multimeter. I'm assuming that you didn't burn anything up otherwise I'm sure you would have noted that. You probably opened a resistor or unsoldered some joint on accident.

If you actually try, you might be able to make your first fix to something you built.

 

[johan851]

Checking amperage and seeing sparks...but the fuse isn't blown. Yeah, you could've fried a resistor or something, I guess...

 

[GigaForce310]

On that note, I've seen fuses that are open but appear to still be intact.

 

[maelstromracing]

On that note, I've seen fuses that are open but appear to still be intact.

Yup, I have seen fuses that looked good but weren't. Check the fuse with another multimeter.

 

[Skeith]

yeah check the fuse.
You shouldent use a multimeter to mesure battery current, batteries, when shorted will load over 30A. Even a small 1.5v 1000mah rechargeable batt will put out over 20 instantaneous amps for a short period. Batteries should be messured by using their printed rating, or if none is available draw a known amperage from the battery from fully charged to dead. mesure the time and you have your current rating.
ex.
If 1 amp is drawn from a battery and it lasts 30 min. the battery is 500mah.

 

[Moto7451]

If you didn't use a resister between the battery and the device that could be why. We were doing this exact thing in our physics class and our teacher warned us that when using the particular analog multimeters we had, if you connected the leads without a resistor, or tried to measure the current of a battery without a resistor in between, the device would draw "infinite current" and fry.

 

[four4875]

its not actually INFINITE current, its justa whole lot, with like .1 ohms resistance

 

[hitokiri_808]

Yeah the meter most likely drew max current and burnt up.