Powers on then off immediately, bad PSU?
Ok I have a imac a1145 that I bought broken, and initially it would turn on randomly and sometimes the fans would speed up to max rpm. So I took out the logic board and noticed 2 6.3v 1500uf bad caps. I replaced them with good ones, but now the imac will turn on for a split second and turn back off. I noticed on the logic board that the #1 green led indicator is on once the power cord is plugged in and #4 red led indicator turns on after I try to start it. I have looked online for what they mean and have gathered that the #1 is tricky voltage (that's vague), and #4 is overheating. Is the #1 indicator specifically for the PSU or does it cover the logic board too? Any ideas or suggestions would be great, I am at my wits end with it and really don't want to start buying unnecessary parts. Thanks for the help.
Here is a link to a previous post with the guide to what the lights mean. From what you describe I wonder if you don't still have one or more bad caps. Are you certain you installed the new caps with the correct polarity? Good luck