CAPACITOR CHECKING ↓↓↓

VISUAL INSPECT
Most defective capacitors especially electrolytic type can be easily detected through visual check. The typical defects include the following:
♦ Bulged appearance
♦ Split vents
♦ Fluid leaking
Image on the left are examples. 



USING CAPACITANCE/ESR METER
We have Peak atlas model on the left and on the right is the B&K Precision 889B that can help the job in checking capacitors more easy and accurate.
Safety first, must discharge the capacitors before checking. Use a resistor with 1K 10W rating to discharge, don't use screwdriver as it may result a huge sparks that can damage small traces or components. Note that some defective capacitors can still make the system run for a period of time and produce good capacitance reading despite ESR goes out of specs. Technically a higher ESR reading than specs signify a bad capacitor. Must replace it immediately to avoid further failures to other components. 

 OPEN  the links below for capacitor ESR table reference.




ESR Capacitor Table (vectron)
ESR Capacitor Table (rmccurdy)
ESR Capacitor Table (eevblog)


ELECTRICAL TESTING FOR CAPACITOR
A simple circuit shown below can be used to check capacitors output wave-forms. Used a diode 1N400x series. Adjust the desired AC inputs, I used 5V AC on my experiment.



Below are the sample of good and bad capacitor wave-forms using the above circuit.




 OPEN  links below for different types of capacitors.




Types of Capacitor 1
Types of Capacitor 2
Types of Capacitor 3