Swapping the Power Supply on an iMac G5 ALS 20 inch
The computer ran fine except for intermittently shutting down. I read about the common problem with power supplies on these models. May as well get a few more years service out of the machine!
Fine. I had done it once before on a 17 inch model. It is a tight fit and offers some challenges in patience, but it went well. Total time about 30 minutes.
While inside take the time to blow the dust out of the machine, upgrade the RAM, and replace the PRAM battery.