If you allways leave your ps3 on standby all the time then its most likely one of your electrolitic capasitors wich are about 20 cents from radio shack or 17p from maplins, your looking for a black or blue cylinder shaped part that is stood upright near the transformer, if its black it will have gold writting on it and say something like '' 16v 2200uf '' and '' RLS 105oc 0628 '' And if its blue the writting will be in silver. On the top part of it you'll see shiney metal with a cross shape in it, if this is rounded on the top and not flat then its blown. or if its pushed up loads there will be some brown type black stuff seeping out the top, if so then it needs changing.
If you want to see a picture of what I mean then just put the codes I gave you that may be wrote on it into a search engine and click images it will come up and you can see what im on about.
But if nothings turning on at all its gonna be a 99 % chance its this.