iMac G3 motherboard repair

IFIXIT doesn't offer any guides or parts for this model because of the risks with a built-in CRT and the age of the unit.

The CRT's are the first things to go given its age. So you may have more than one problem here.

Opening these systems does put you at risk of electrical shock, so be very careful! I would strongly recommend not trying to work on this system if you don't understand how to bleed off the charge on the CRT & power supply correctly.

You will need to look at eBay or google for parts and your choices will be limited. Given the age & costs I would think you may want to put your money into a new unit. This system can't run any newer OS or apps (OS-9) and the early versions of OS-X (max 10.3.9) as its a PowerPC based system not Intel which is used today.

In any case make sure you dispose of your unit carefully as the amount of lead in it can damage the environment if put into a land fill.