do you have the original power adapter for it? what are the specs of the adapter?
usually, pc devices like that are only expecting 12.0 v and don't fare too well when the voltage fluctuates more then 0.2-0.3v..
also, i have seen that plug before--on a couple of external hdd's i have, and the ones i have, the power adapter actually outputs both 12v and 5v. so you'll also want to try to confirm that the power adapter is 12v only.