In article , Roger R
writes

The mains input fuse on the board has blown but nothing is burnt.

I'm hoping someone can advise on the likely faulty component.

Agreed with Arfa. If the mains fuse is silvered/blackened on the inside
of the glass (hard to tell from the photo), it's a short in the primary
side, most likely one of D1/2/3/4. D2[obscured] looks like it's been
farted about with, have you had someone look at this supply already?

There's no primary-side switching transistor, which is unusual. Maybe
it's inside IC1, but your picture isn't clear enough for me to read the
markings on IC1 to look up the spec.

IC1 also looks slightly brown on the surface, as if it's overheated.
It's certainly a suspect.

There also appear to be two D2s, unless the green capacitor C4 is
obscuring another number of diode D2x, the one I refer to as
D2[obscured] above.

Nasty cheap design, intended to just get you past the warranty period
before expiring.

--
Fred Bloggs