Hey there friends,
How to check an electrolytic capacitor ? and why ? I mean for both analog and digital multimeter.
How to check an electrolytic capacitor ? and why ? I mean for both analog and digital multimeter.
Practically, you can't really.
You can get a feel for how fast it charges or discharges and some indication (maybe) of leakage, but you can't actually measure the capacitance or the ESR.
You need a meter capable of measuring these.
You can get a feel for how fast it charges or discharges and some indication (maybe) of leakage, but you can't actually measure the capacitance or the ESR.
You need a meter capable of measuring these.
I just have an analog multimeter.
I just want to test whether my capacitor is working or not and not on determine the capacitance
Then you need a capacitance meter. A number of digital multimeters do have a capacitance function.. do some google searching
Dave
Then you need a capacitance meter. A number of digital multimeters do have a capacitance function.. do some google searching
Dave
Capacintance meter is to check the capacitance value of the capacitor and this is not I want to.
I just want to check whether the capacitor is working or not
jackorocko
- Apr 4, 2010
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I am sure you searched on google first, right?
if it is a significantly large capacitor, you might be able to use your meters ohm setting. Knowing that a capacitor is a short when the voltage across it is zero. Remember that on an analog meter the polarity is reversed for the leads in the ohm setting.
But even that will not tell you if the capacitor is good. A lot of different factors go into whether a capacitor is good for a given scenario.
if it is a significantly large capacitor, you might be able to use your meters ohm setting. Knowing that a capacitor is a short when the voltage across it is zero. Remember that on an analog meter the polarity is reversed for the leads in the ohm setting.
But even that will not tell you if the capacitor is good. A lot of different factors go into whether a capacitor is good for a given scenario.
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Then I need a capacitance meter ? Or how can I exactly know my capacitor is in good condition ?
There are many factors that can affect a capacitor's function. Not all are easily tested for, and there is no single piece of equipment that can test them all.
For some functions the capacitor's ESR may not matter, but its capacitance may. In other cases the reverse is true. Sometimes stability over temperature is an issue, sometimes it's not. Sometimes leakage is a concern, sometimes not.
So a capacitor may be a total failure in one circuit, but entirely OK for another. If one defines "Good Condition" as meeting all its specs, then you may have a hard time testing that. If you know what specs are important, then you can get test equipment to help you test those particular ones.
The easiest option is often just to get a new capacitor and assume it is OK. If it fixes the problem then your original capacitor was (by definition) faulty is some respect.
If you can tell us what value your capacitor is then we may be able to tell you what you might see if you place it across your multimeter on several ranges.
For instance, a capacitor over (say) 100uF placed across an analogue meter on the x1000 ohms range should have the meter swing almost to zero, then swing back across to infinity -- the speed ot swings back to infinity is related to the capacitance -- it will be slower for increasing capacitance.
If you then change the meter to a voltage range you should see a voltage across the capacitor. You may or may not see it slowly decay back toward zero.
These tests will not tell you that the capacitor is good, but they will tell you that it is exhibiting some fairly significant "capacitor action"
For some functions the capacitor's ESR may not matter, but its capacitance may. In other cases the reverse is true. Sometimes stability over temperature is an issue, sometimes it's not. Sometimes leakage is a concern, sometimes not.
So a capacitor may be a total failure in one circuit, but entirely OK for another. If one defines "Good Condition" as meeting all its specs, then you may have a hard time testing that. If you know what specs are important, then you can get test equipment to help you test those particular ones.
The easiest option is often just to get a new capacitor and assume it is OK. If it fixes the problem then your original capacitor was (by definition) faulty is some respect.
If you can tell us what value your capacitor is then we may be able to tell you what you might see if you place it across your multimeter on several ranges.
For instance, a capacitor over (say) 100uF placed across an analogue meter on the x1000 ohms range should have the meter swing almost to zero, then swing back across to infinity -- the speed ot swings back to infinity is related to the capacitance -- it will be slower for increasing capacitance.
If you then change the meter to a voltage range you should see a voltage across the capacitor. You may or may not see it slowly decay back toward zero.
These tests will not tell you that the capacitor is good, but they will tell you that it is exhibiting some fairly significant "capacitor action"
In many cases - just applying the NP Voltage ( with correct polarity) will do the job, if anything has gone wrong it may not hold full voltage ( wear Eye Protection - they can fail in interesting ways).
If it is a older Cap that has been out of service - it may need to be reformed ( look up reforming electrolytic capacitors).
-- Also - if an older cap - just replace it if this is for anything critical or valuable. Electrolytics have the shortest life span of most circuit element.
If it is a older Cap that has been out of service - it may need to be reformed ( look up reforming electrolytic capacitors).
-- Also - if an older cap - just replace it if this is for anything critical or valuable. Electrolytics have the shortest life span of most circuit element.
Shyamal796
- Mar 19, 2012
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Capacitance meter is needed.
You can test electrolytics with the ohm meter on the 2M scale. Just multiply the 2MX the capacitance and it will give you the time in seconds for it to charge to 63% Example: 2MX10uf=20sec. But like Steve said, it could still be bad. If you don't have an esr meter, you can apply like a 100KHZ signal and observe the voltage on a scope. Take a known good one and a known bad one to note the voltage difference across the cap.
I have never actually tried the O scope trick.
I have never actually tried the O scope trick.
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Shyamal796
- Mar 19, 2012
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So many thanks
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