testing caps less than 1uF

[shaunbt123]

Hi there can someone tell me if there is a way to test capacitors below
1uF i have a peak atlas esr meter but the minimum it will read is 1uF.i recently needed to test some caps below this value.
thank you.
shaun.

[mariushm]

Re: testing caps less than 1uF

Capacitors under 1 uF are usually ceramic or tantalum capacitors. You don't find often the problems electrolytic capacitors have in these types of capacitors.

Those capacitors either fall short and burst in flames (tantalums) or fall short or most often crack open (in case of ceramics).

So check for those and when in doubt, replace them.. you can purchase rolls of 5000 ceramic capacitors for 10-30$ so few people waste time checking 0.1uF ceramic capacitors.

[euromatlox]

Re: testing caps less than 1uF

Many cheap multimeters can read smaller capacitors, up to about a few microfarads. Also available are electric capacitance meters, which are better for capacitance only measurements (they can read very small pF caps and bigger uF caps too). There is also a pretty popular USB-powered measuring device for inductances and capacitances, see youtube video below.

http://www.youtube.com/watch?v=cpxbwjDny0E

[Mrx3750]

Re: testing caps less than 1uF

I have a capacitance meter. It doesn't test for ESR, but it reads capacitance from 200 pf, to 20,000 uf.

[PeteS in CA]

Re: testing caps less than 1uF

Adding to what mariushm posted, large form-factor SMT ceramic capacitors tend to fail leaky or short-circuit. The leaky ones can be tricky to diagnose, unless they are visibly cracked (burned through 1.5-2 man-days yesterday and the day before doing just that!). The shorted ones can be pretty nasty, suddenly glowing orange or cherry red when power is applied, sometimes severely damaging or destroying PCBs.

Large form-factor SMT monolythic ceramic capacitors are evil! Necessary and unavoidable, but EVIL.