Solved Led 1 Turns On With One Blink And Stays On Imac Intel 27 Emc 2390

Chosen Solution

Imac doesn’t turn on, all other LEDs 2.3.4 stay off, only turns on by bypassing the SMC with full speed of fans and no display no Chime, # 2,3,4 LEDs stay off even when bypass the SMC. Tested With:'

1. Different RAM.
2. Different Processors intel i5.
3. Tried to Turn without Graphic Card.
4. Without RAM. NO Luck! Have no idea about Output Voltages of Power Supply. Any help Would Appreciate thanks.

That LED only indicates startup voltage is present (power from mains to cord to board). I do not have any schematics or information about output voltage from the PSU. Maybe some who does will chime in. If this answer is acceptable please remember to return and mark it.