I have an old iMac G4 (USB 2.0) that I would like to get up and running again. The problem is, the iMac won't power on, much less boot up. I've tested the power cable, it works fine; and I've reseted the PMU (see the article: http://docs.info.apple.com/article.html?artnum=95165). None of this has helped. How would I get this old 2003 iMac working again?
applemaz
Registered
Unplug the power cord from the computer. Look at the back and keep your eye on the fan. Plug in the power cord. Did the fan move at all? Next, attempt to turn on the computer while looking again at the fan. Did the fan attempt to spin when you tried to turn it on?
Next, open the case. While it is plugged in, but not on, do you see a glowing LED on the logic board? Watch the logic board and try to turn the computer on. Does anything on the board light up for even a second? Check that the cables from the power supply are connected snug to the logic board and try starting it again.
If you do all this and see no signs of life, then either the power supply or the logic board are bad. On such an old machine, finding a replacement part isn't going to be worth it.
Next, open the case. While it is plugged in, but not on, do you see a glowing LED on the logic board? Watch the logic board and try to turn the computer on. Does anything on the board light up for even a second? Check that the cables from the power supply are connected snug to the logic board and try starting it again.
If you do all this and see no signs of life, then either the power supply or the logic board are bad. On such an old machine, finding a replacement part isn't going to be worth it.
DeltaMac
Tech
Small clarification for this (I guess applemaz didn't realize which Mac this is 
)
The fan for an iMac G4 (the one with the chrome swivel neck), is in the top of the round base, and not too easy to see, but you should be able to feel the airflow, and hear the fan running.
There would be a power LED visible (only with power on) by removing the bottom access plate, no need to open the case just for that. You really can't see much of the logic board then, but the power LED will be visible, assuming the system does power on, otherwise, it will probably be off even with power cord plugged in.
You can't check any cables, unless you continue with opening the bottom case, which is a little tricky to open because you have to break to seal created by the heat sync compound. Once inside, you can also check the battery, etc.
)The fan for an iMac G4 (the one with the chrome swivel neck), is in the top of the round base, and not too easy to see, but you should be able to feel the airflow, and hear the fan running.
There would be a power LED visible (only with power on) by removing the bottom access plate, no need to open the case just for that. You really can't see much of the logic board then, but the power LED will be visible, assuming the system does power on, otherwise, it will probably be off even with power cord plugged in.
You can't check any cables, unless you continue with opening the bottom case, which is a little tricky to open because you have to break to seal created by the heat sync compound. Once inside, you can also check the battery, etc.