Which is the main component of the PSU
We need to know what's in there so we can suggest what to test. 'If' it's a 50/60Hz mains transformer, then there's a decent possibility that it's internal heat fuse has died - but if it's a switch mode PSU in there, it will read much like a blown heat fuse if it's good.
It looks like there's only a single rectifier on the board, as well as a soldered in fuse - half wave rectification would be no good, so it could be DC coming up, and the rectifier is a polarity protection diode?.
But basically we're all blindly guessing, because the bits we need to see are in the bottom.