Advent t100 all in one screen blank

I have a advent all in one t100,My problem is a complete blank screen, When I switch on all lights and computer starts up.. you can even hear xp startup but the screen stays blank!! I also think the fan is not coming on!! I have read that this model More akin to a laptop than a desk computer has underpowered psu and that I should replace it with a Delta 220w sadp-220db b psu or a Dell da-2 d220-01(have to alter the wiring but basically similer to the Delta),

My question is:- would the psu be causing the problem 2. does anyone know where I could buy one ( as I seem to be having trouble locating either). 3. or is it something to do purely with the screen ie light ect.. or any thin else??
I really would apreciate all the help I could get..
cpu intel pent 4,chipset intel 865pe