How to check a capacitor with a Multimer
Capacitor is a basic components that use a lot on PCB. Film capacitor and ceramic capacitor has not polarity , but tantalum capacitor and electrolytic capacitor has polarity. Always discharge big capacitor and high voltage capacitor before testing and test it when there is not voltage present at the circuit. Unplug and remove power from circuit before measuring. Failure to provide those condition before testing it is a high risk of electric shock and the multimeter will damage too.
Step to check a capacitor with Digital Multimer.
1. Must remove power , switch off and discharge big capacitor , high voltage capacitor before testing. Test capacitor is performed when it is not on PCB ( not connected on circuit).
2. Turn the switch range to capacitor test function.
3. Connect the multimeter test leads with capacitor terminals.
4. Read the measured value.
Good capacitor will get measured value closet to it's value that print on label.
Shorted capacitor will display OL.
Open capacitor will display nF value which is capacitance of test leads only.
Degrade capacitor , measured value is too low and amount is different from original value.
Step to check a capacitor with Analog Multimer.
1. Must remove power , switch off and discharge big capacitor , high voltage capacitor before testing. Test capacitor is performed when it is not on PCB ( not connect on circuit).
2. Turn rotary range switch to appropriate range as list below.
X10K for capacitor value : less then 10uF
X1K for capacitor value : 10uF - 47uF
X100 for capacitor value : 47uF - 470uF
X10 for capacitor value : 470uF - 4700uF
X1 for capacitor value : 4700uF and more value
The good capacitor , the needle will move forward then backward at the end of scale. Electrolytic capacitor has very little leaked current so the needle will not fully move backward for some capacitor.
The needle will move forward then backward at ∞ for a good capacitor.
