Will not power up but try's

HI i have an iMac A1224 that wont power up it try's but doesn't quite make it the fans and hard drive kick on for just a few seconds. I checked the voltage on the power supply and pin 1, is at 0v / pin 2,8.3v / pin,3 0v pin / 4, 8.26v pin / 5, ol pin / pin 6, 0v / pin 7, 8.3v / pin 8, 8.3v / pin 9, 12.27v / and pin 10, 0v... is that good or bad? as far as the power goes?? light at the leds number one is lit all the time and when you press the power number 2 comes on for a few seconds the shuts off along with the fans number 3,4 don't light.