check all plugs,back left button to turn on/put to sleep.
If a G4 iMac is working but starting up without the chime it may have been shutdown with the sound muted or there may be headphones plugged in. If it is not starting up at all then it will need repairing.
The iMac G4 is able to run any version of Mac OS X up to and including, version 10.5 (Leopard).
To load a disc in an iMac G4, locate the slot-loading optical drive on the front of the computer. Gently insert the disc into the slot with the label facing up; the drive will automatically pull it in. Ensure that the iMac is powered on, as it will not accept a disc when off. If the disc doesn't load, check for obstructions or ensure the disc is clean and undamaged.
The G4 can shoot up to 25 bps
I own an iMac and don't have that error. This should no happen and you should look into memory allocation before you next start it up.
You can plug up your 2012 iMac when you are finished using it. Nothing will happen to the iMac. After the iMac is fully charged, make sure to unplug it.
No. The slot-loading drives on all current iMac models (and most previous iMac models) will only accept standard 12cm (120mm) diameter discs. Smaller discs may (and usually do) cause problems with the drive, up to and including complete drive failure. Smaller discs require tray-loading optical drives; the only iMac models that included tray-loading optical drives were the early iMac G3 (CRT) models, and the iMac G4 ("Sunflower," or "Desk Lamp" style) models.
This seems to be more of a technical problem. You should take your iMac into the nearest Apple Authorised Service Centre for help.
If there is a power cut then the Mac will be off. The Start Up Automatically.... option will automatically restart your Mac when the power comes back back on.
The Six iMacsThere have been six iMacs in the time of Apple's history up to now. First, there was the Egg-shaped G3 with a multicolored translucent plastic coating and CRT monitor.Then there was the G4, the half-dome shaped computer with a freely attached LCD monitor.Next there was the G5. The G5 is a slim, rectangular box on a stand with a LCD monitor.After that, there was the G5 with a built-in iSight camera and Front Row. This retained the shape of the first G5.Finally there is the Intel iMac. This retains the shape of the previous iMac but as an aluminum and class casing rather than a plastic one. This iMac also has a built-in iSight and Front Row.
You cannot run the newest OS on an older iMac with the Power PC processor. It must be running on the Intel processor. You can however update an older Mac with all the updates available for that model iMac. Just click the Apple icon and choose Software Update.
One can see old iMac Commercials in Youtube which features the different types of commercial about old iMac such as All Mac vs. TV adds, Apple iMac vs. HP, and iMac G3 starting up.