Chosen Solution
Hi, I’ve got a 21.5" iMac that will not power on, there is no sign of life (no fans starting up etc). I’ve taken it apart and have noticed that only one of the diagnostic leds lights up but when the power button is pressed the led goes off. So far I’ve re-seated the PSU, motherboard, tried disconnecting everything bar the power button from the motherboard, bypassing the power button, resetting the SMC and Pram but nothing seems to work. I’ve been in touch with the guys at Apple and they have told me to try a new PSU first then if that doesn’t work try a new motherboard. As you may well know this is a rather expensive suggestion, so what I ask is, has anyone else had the same problem and what was the outcome? Thanks
Most techs use the swap out method as just being quicker when you get a dead system. One could also use the meter/scope method. Where you use a Volt/Ohm/Current meter and/or oscilloscope, then using a good set of schematics and good electronics knowledge tracing out the paths and checking things out. I would swap out of the power supply first - Sorry
