HELP My Imac (White) wont turn on

[imac10]

Please help me out. My imac wont turn on. It started about six months ago when suddenly our house was hit with a power outage and she automatically turned off. Then after that moment it continued powering on and working fine but sometimes when I have her turned off and I unplug the power cable and then try replug it and put it back on it wont start. She will then be like this for hours or days. Please help me out.

[Hellhammer]

http://guides.macrumors.com/Mac_doesn%27t_boot

[maril1111]

Have you tried using a different PSU and see if it makes a difference maybe the outage somehow made your psu to be faulty.

[kbfr08]

Check the fuses in your PSU, if they're popped, you'll need to buy a new one of the same value (should be printed on the pcb), and solder it to the board. I usually keep old electronics and pcbs to salvage chips from, so check any old PSUs for identical fuses.