Testing cap using ohm meter?

[upthepunxxx]

I was gonna test some large value electos (2200uf) on the cap setting of my dmm but it doesn't seem to want to work. I checked their resistance and the new and old one are reading all over the place. If the caps are reading like a couple hundered k to a couple mega ohms that means they are bad right? I'm having trouble getting a good ohm reading on the ones I'm replacing as well as the new ones.  Anyone know of a good way to test larger value electrolytics?

[kothoma]

that means they are bad right?

No. Caps block DC. Having a high (infinity) DC resistance is expected. Never tried to measure it though...

[copachino]

that means they are bad right?

No. Caps block DC. Having a high (infinity) DC resistance is expected. Never tried to measure it though...

You can use an analog multimeter... And use continuity... If the caps are ok then the neddle goes up fast then comes back slowly.. If they stay up they are bad

[blearyeyes]

If your meter has a capacitor setting use that..
Caps are strange creatures... It's worth taking some time and researching them on the net.

Dan

[flanagan0718]

What multimeter are you using, I think that will determine if you can test them or not.


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[RobA]

I was gonna test some large value electos (2200uf) on the cap setting of my dmm but it doesn't seem to want to work. I checked their resistance and the new and old one are reading all over the place. If the caps are reading like a couple hundered k to a couple mega ohms that means they are bad right? I'm having trouble getting a good ohm reading on the ones I'm replacing as well as the new ones.  Anyone know of a good way to test larger value electrolytics?

My DMM's cap setting never worked. Everything on it works except for the frequency counter and the caps. I don't know why either.

There are a couple of things you can do to check to see if the cap is working. You can charge the cap with a battery and then measure the voltage across it. It should charge up and store the voltage and then slowly discharge it through the meter. You can even charge the cap with the DMM by putting it resistance mode and connecting the meter across the cap. Then turn the meter to volts and read the voltage. Although, this method is slower than just doing it with a battery.

If you wanted to do some math, you could discharge the cap and then hook it up in a circuit with a resistor and measure the time it takes for the voltage to rise to a set value. Here's a link to the example circuit an a calculator to do the math, http://ladyada.net/library/rccalc.html.

[upthepunxxx]

Anything over 100uf freaks out my cap setting on my dmm. I'll do some more reading and see what I come up with. Thanks homie!

If your meter has a capacitor setting use that..
Caps are strange creatures... It's worth taking some time and researching them on the net.

Dan

[upthepunxxx]

Its a decent ex tech I got for work. I think it was like 120 new. Can't remeber the model number as it's at home today.

What multimeter are you using, I think that will determine if you can test them or not.


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[upthepunxxx]

Thanks for the tip man! I'm gonna give the battery test a shot tonight when I get home! 

I was gonna test some large value electos (2200uf) on the cap setting of my dmm but it doesn't seem to want to work. I checked their resistance and the new and old one are reading all over the place. If the caps are reading like a couple hundered k to a couple mega ohms that means they are bad right? I'm having trouble getting a good ohm reading on the ones I'm replacing as well as the new ones.  Anyone know of a good way to test larger value electrolytics?

My DMM's cap setting never worked. Everything on it works except for the frequency counter and the caps. I don't know why either.

There are a couple of things you can do to check to see if the cap is working. You can charge the cap with a battery and then measure the voltage across it. It should charge up and store the voltage and then slowly discharge it through the meter. You can even charge the cap with the DMM by putting it resistance mode and connecting the meter across the cap. Then turn the meter to volts and read the voltage. Although, this method is slower than just doing it with a battery.

If you wanted to do some math, you could discharge the cap and then hook it up in a circuit with a resistor and measure the time it takes for the voltage to rise to a set value. Here's a link to the example circuit an a calculator to do the math, http://ladyada.net/library/rccalc.html.

[blearyeyes]

Yea I guess your meter has to have enough juice to charge them up.