No Screen, LED #2 Off, No Chime
Hi so the iMac will not turn on, the screen stays black and there is no chime.
I opened the iMac and noticed that LED #1 stays on but when I press the power button to try and turn on the iMac, LED #2 never turns on.
I can hear the HDD spin up when I power on the iMac but no fans turn on. So I’m not sure if the PSU is bad or not.
I tried to power on the iMac with everything put together, without an HDD, and without RAM, LED #2 never lit up.
I ran a test on the RAM and HDD and both passed, so my question is if it is more likely to be the PSU being bad, the cable to the logic board being bad, the logic board being bad, or the CPU being bad.
Questa è una buona domanda?
It’s most likely not the CPU. Have you tried holding different boot keys? if everything leads to a black screen and single led. I would try pulling the cmos battery, reseating the video cable, cleaning it out and disconnecting as many components that are not necessary for the machine to post, Such as the webcam, DVD drive, etc. Try different memory. Power supplies are cheaper than Motherboards, and either could be the issue. However, be thorough with your checks first.
as far as I know, I don't think the iMac has a CMOS battery. I've already checked the display cable. I also believe even with the display cable unplugged and memory removed you should still be able to see the diagnostic LEDs go from 1-4 if everything is working?
da Dylan Nguyen
This series does indeed use a CMOS battery!