Last night, I heard a spark noise while my mac power adaptor was connected, and the charger stopped charging my machine. There was no light on the connector. I should also say that the cable attaching to the adaptor was torn. So after reading instructions for dismantling the charger, I cracked it open and cut the cable before the plastic piece inside the charger. Then, I tested if the AC charger was having any output DC voltage with a multimeter. But it did not detect any. Now, do I have to assume that the unit is dead or is there some fuse which needs to be replaced?