My iMac G3 overheated pretty badly earlier on in its life. The cooling wasn't obstructed, but the drive in it ran hot and the machine was positioned in direct sunlight for a lot of its life (being a former education system). It also had the usual wear and tear from school kids, coin in the optical drive, pins in the speakers, all that.
The PAV was toasted. System would power up but couldn't sustain a constant voltage to the Cathode Ray Tube, so it had this nice dimming and then suddenly over-brightening effect that got worse with age.
I ended up changing out the PAV Board, CRT, Hard Disk, Speakers, Internal Frame (which was baked and cracked) and Optical Drive. It's not actually the same iMac anymore, with only a few parts remaining from the original system, including the lower EM shield, the drive cage, the logic board, down converter and the Graphite plastics. Now some of the graphite plastics need to be replaced.
Bah. Time to let it go I think.
Strangely the Tray Loader iMac, which was known for heat issues even more than the Slot Loader, has always been a more solid machine in every case i've come across one. They do heat up, but I don't often see one with power issues, the cases are stronger, the plastics last longer. Drive mechanisms don't fail as often. The Slot Loader may have been a refinement of the original design (as Steve Jobs suggested) but it was a major step backward overall when it came to the engineering.
As for the OPs issue... I can almost guarantee that the hard disk was failing considering the sudden nature of the fault. Good move on opting for replacement.
The PAV was toasted. System would power up but couldn't sustain a constant voltage to the Cathode Ray Tube, so it had this nice dimming and then suddenly over-brightening effect that got worse with age.
I ended up changing out the PAV Board, CRT, Hard Disk, Speakers, Internal Frame (which was baked and cracked) and Optical Drive. It's not actually the same iMac anymore, with only a few parts remaining from the original system, including the lower EM shield, the drive cage, the logic board, down converter and the Graphite plastics. Now some of the graphite plastics need to be replaced.
Bah. Time to let it go I think.
Strangely the Tray Loader iMac, which was known for heat issues even more than the Slot Loader, has always been a more solid machine in every case i've come across one. They do heat up, but I don't often see one with power issues, the cases are stronger, the plastics last longer. Drive mechanisms don't fail as often. The Slot Loader may have been a refinement of the original design (as Steve Jobs suggested) but it was a major step backward overall when it came to the engineering.
As for the OPs issue... I can almost guarantee that the hard disk was failing considering the sudden nature of the fault. Good move on opting for replacement.