Blown Electrolytic and SM Regulator Chip

[itdontgo]

I have a board with a burst electrolytic which is connected over the 24V DC input terminals (through a diode).  The switch mode regulator chip on board has also blown open - this comes after the capacitor i.e. it regulates the 24V to a lower voltage.  There is no input protection on this board unfortunately!

I would assume the only way an electrolytic capacitor will fail is through over voltage or perhaps through longest of long shots ripple if it was exposed to some severe AC currents (in this case it isn't though).  It's also a low power cool running board.  Plus the diode will stop reverse voltage.

My possibly stupid question is can it possibly be anything else apart from over voltage?  It is 35V cap and the diode has a reverse voltage of 40V.

[dannyf]

perhaps through longest of long shots ripple if it was exposed to some severe AC currents (in this case it isn't though).

If it is a switching mode regulator, the electrolytic capacitor by definition sees "severe AC currents" all the time. No way around it, not by a long shot.