When testing caps you should get ?

[JasonG]

Hi
I have been testing some caps for a booster I am trying to make. When I test them on my multimeter the resistic goes up till the meter says "over" its out of its range. ( Its auto ranging) I have read up on it but the sites I have seen just talk about analog meters.
My conclusion is that the caps are still good. Right ?
thanks!

[GibsonGM]

I dunno about your meter, but my DMM is similar. It's pretty accurate for caps of say 1nF up thru 100uF.   Go into pF or high uF, and I get weird readings.  I'm assuming if you're reading higher & higher, then into the out of range, the cap is good.  That is how they behave.

One good way to test caps is to put it on a breadboard in series with something like a 1K resistor (esp. for small value caps, say <1uF).  Set your meter for resistance and connect the leads to the resistor and other side of the cap.  It should slowly rise and top out at infinity as the cap charges thru the resistor (providing the RC time constant).  The formula is R in megohms and C in farads = seconds to charge, IIRC.  The resistor slows it down for the smaller caps.  Try using the resistance rather than the cap function on larger caps to check them.  They never really fully charge - 1 time constant is equal to 63% of the charge capacity of the cap.