how to check cap with voltmeter?

how would i go about checking my cap to see if it is working?  i have a voltmeter.....do i just put in on the + and - or should i go+ to ground??? any help greatly appreciated1 JL 12 w3 D4

1 MTX 421 D Monoblock

1 Sony Xplod 75x4

Front: Alpine SPX-177A

Rear: JL audio VR690-CXI

take the cap off line, be careful not to ground the + side. put your voltmeter + to+ and -to - If it is woking it should  show 12volts and hold a charge until discharged. once again caps can be fire works show if you ground that  + side.Big Dave

Be very careful handling a charged capacitor, as they can hurt you.  I have a scar across my right elbow where one discharged through me when I brushed against it years ago.  Burned the skin right off it did.  And if you connect a meter across charged terminals in ohms or current mode, the meter can blow up in your hand.  Why do you think it's not working?

DYohn wrote:   Why do you think it's not working?

because the led light is not lighting up, i just want to check voltage to make sure its working before i go taking it back to the person i bought it from1 JL 12 w3 D4

1 MTX 421 D Monoblock

1 Sony Xplod 75x4

Front: Alpine SPX-177A

Rear: JL audio VR690-CXI