My old 10" JBL subwoofer blew out like that, on a few occasions. The first time, it woke up in the middle of the night, making whining noises. I went and unplugged it, then plugged it back in... It start blasting 150watt shots full blast into our apartment BOOM BOOM BOOM BOOM... heh
I found on a forum the bad capacitor that had blown, and fixed it for a whole 39 cents, and it was good to go for another 2 or 3 years. I did put a switch on the back of it at that point, to turn off the power completey. It went out again the other day, and I fixed it one last time, then jacked it up and ran a new JBL Sub12 under it.. hehe Now, it's someone else's problem: I gave it to my dad and he sold it at the flea market.
