Q: my emac was working, now turning on for 1 minute and stop.

Is you computer really an eMac or is it an iMac? If you don' know then please click the Apple symbol in the upper left of the display and click About this Mac. Then please post what it says in that box.

Well this is an iMac forums. Considering the age of your computer I suggest that you retire it and get a new machine.

I still use my eMac everyday, not as fast as my Mac Pro, but far more useful for my purposes.

Anyway, shutting down after one minute sounds a bit like a heat issue off hand... anyway you can blow some dust out?