Completely Black Screen - No chime on boot
I have an old 2006 iMac (A1174; EMC 2105), it hasn't really been used since 2010 because it was having several issues mostly shutting down with no warning. I knew the issue was the power supply so I thought it would be a fun project to replace it. After putting the display on i plugged it in to test the Computer, it starts up but with a blank display, I hear the ODD spinning and the LED indicator under the right speaker lights up, 2 seconds later the HDD fan starts spinning at full speed (Note: there is no Hard Drive connected and i don't believe the sensor is either, so i think that is normal) the ODD fan spins as well. I went back to make sure everything was connected but still nothing. I read online that there are diagnostic LEDs but i cannot find them on this model. I think the problem might be the Logic Board (Because no boot Chime) but i don't know if it could be the display, GPU, Inverter or a broken cable.
I Would like to know where the Diagnostic LEDs are located (i checked to the right of the RAM slots and there is a silver connecter but no LEDs).