Question : Problem: What is the function of capacitors within power supply units?

Hi Everyone;

          From a recently closed post, I was advised to check the capacitors within the power supply and on the motherboard.  It is my understanding the capacitors look like small cylinders which should be flat on top with an x at the top.  If the top of the capacitor bulges out, then, the power supply or motherboard is bad or defective.  In any case, what exactly is the function of capacitors?  Do they store reserved electrical current for components which is furnished upon demand?

            Any shared thoughts to this question will be appreciated.

           Thank you

           George

Answer : Problem: What is the function of capacitors within power supply units?

Capacitors act as a filter in electrical / electronic circuits.  In a DC power supply they help keep the voltage level constant.  Most power supplies have AC sources, that is rising and lowering voltage levels which will affect DC output, so the capacitor is used to smooth out these changes.

http://www.play-hookey.com/dc_theory/components_capacitors.html

http://www.gaep.com/tech-bulletins/precision-ccs-power-supplies.pdf