multimeter help

[bleeder]

I have this old analogue mm I'm figuring out how to use.

I learned how to measure dcv so far.
The black probe is in (-)COM and the red in (+)V-ohm-A
between them it says 250ma max

would some things be higher than .25 amps though?

I was trying to measure dc amps on a psu I'm testing with.
My function nob has these for DCA: 250m, 50u <--(cursive u) (250mV)

So I was trying to measure the 12v rail, but set on 250m, when I have the black probe on ground and the red probe on the 12v, it simply kills the psu. When its on the other 50u, it just shoots all the way to 0 (dont know what scale they are using in these settings)

What does this mean, whats going on?


Also, I have two more plugs for the probes, they are OUTPUT and (+)DC 1000V
When would I use these?

One last thing, is that the tips of my probes are a little thick, not very pinpoint precise. Would it affect anything if I filed/sharpend them to a finer point for more presision?

Thanks :)
I'll probly be buying a cheaper dmm at radio shack next time I go there too :cool:

[STEvil]

get a digital one, and dont measure amps unless you have a device hooked up.

[Ragnarok]

rofl, u r trying to measure the voltage with the multmeter set on amps? u r short circuiting ur psu..

got a pic of the unit???

[bleeder]

ah no, I was trying to measure the amps set on amps

i figured it must have shorted it. just don't get how measuring amps works. I guess it isn't a good idea measuring the rail since this is 250ma max :S yeah it makes sense to have a device connected
:am:

i'll try to find a pic of the unit somewhere, or borrow a dcam sometime soon

[koensa]

amps = reading in serie
voltage = reading in parralel

[phobos]

ah no, I was trying to measure the amps set on amps

*rofl* that is a full short circuit! You MUST apply load to the PSU and measure the current in series to the load.
You can't just plug a MM to the PSU and measure the max current.

[Hell-Fire]

Guys...be aware that he may be learning electronics and thats why he is asking his question.

It may sound funny to us, but for those who dont know electric circuits, its a common mistake. I bet if you ask people how they would check the ampage of something using a DMM, I figure most would say to set it to read AMPS.

Lets keep the kidney punches to a miminum and the guidance to a max...know what I mean.