Skeleton Man wrote:

These are rarely repaired, however often the problem is bad electrolytic
capacitors. Occasionally one will grenade in such a way as to cook
virtually every semiconductor in it, but often they just refuse to start up.
Check
thestandby power supply, if that's ok then try to figure out why the main
one
won't start up.

I think you may be onto something.. I took a closer look and several
capacitors appear to be bulging a bit at the top.. one does have brown
stuff around the edge, but I figured this was rust or crap that collects
like dust, etc.. (but none of the others have this).. all the capacitors
in question are 1000uF - 2200uF, 10 - 16V.. the small ones look fine..

Replace ALL the larger caps even if they aren't bulging. Looks like you have a
PSU made with 'bad caps'.

http://www.badcaps.net/pages.php?vid=5

NB - the caps on the secondary side MUST be 'low ESR' types made for smps use.

Graham