Short answer, there's a short someplace downstream of that fuse.
Long answer... how good are you with electronics?
Could be a transistor blown, cap, resistor... everything down to a transformer. Take a look at all the boards and see if you see signs of obvious distress (or to word it in a way that may be more familiar to you, destruction) to any of the discreet components.
For instance, you may be able to see a blown up transistor, although it's more likely to be that several components went at the same time. If you can determine the part number (in the case of a transistor) or the rating (in the case of a resistor or cap) of the defective component, and you may likely have to scour for a schematic, you really don't have much to lose if you feel like firing up the iron and trying to replace whatever looks burned up.
Again, even if you replace what seems to be an obvious problem component there may be something else going on down the like that caused to to go, but what the hell, right?