I bought the power supply a year ago and have only used it for 4-8 hours until now. I've just started using it again and it's blowing my 5A fuses let and right. I thought maybe it was the fuse holder, so I wired the AC in directly to the power supply. The power supply just hums and won't output any DC power. The power supply be fried or what? Does kelinginc have an exchange policy?