Peterson 520 strobe tuner

Hello. I know this isn't a pedal, but close enough (har har). I just got this for free from my band director since he was going to throw it out and it does not work. It blows a fuse every time it's turned on, and gives of a bit a of smoke from the "power" circuit board from some of the resistors. I assume there is a short to ground somewehre in it, but I can't figure it out. What are the possible causes? Thanks!