Hi friends. I have a doubt about capacitor that if a capacitor has burned out, would it get short circuited or open circuited?

 

They can fail either way; open or shorted. Frequently, one (or more) other components in the circuit are destroyed along with the capacitor. A capacitor that failed shorted might get burned open during the failure.

 

Most caps will dome on the top when they go out, but the biggest problem is ESR (equivalent series resistance). There is a unit called the Capacitor Wizard which is a good unit for a quick test and accurate test for both value and ESR. Its also good in circuit testing, but not always. I use this and the LC103 by sencore.

Another an even less accurate is using a VOM or Digital Meter. I don't bother with this type of test at all. Price wise the Capacitor Wizard is a good unit for the price, around $200.00.

Most of the time they don't short or open, they just change value and show a increased ESR.

 

Failing electrolytic capacitors may bulge or even leak fluids, but they may also fail by slower evaporation of the electrolyte without obvious visible signs. The bulging capacitors may sometimes be poor quality devices which have failed prematurely. Alternatively, they may have been subject to excessive voltage or ripple current, or they may have suffered voltage reversal, all of which can lead to quite dramatic failure.

Other types of capacitors such as ceramic or plastic are less likely to look obviously damaged, unless there has been a substantial release of energy in which case cracking, bulging, or burning are all possible. Wax or oil filled capacitors may fail without anything leaking out, but clearly any part which is leaking anything should be regarded with suspicion, even if apparently operational.