G5 iMac Will Not Turn On - Power Supply Diagnosis?
My A1145 20" iSight PPC G5 iMac will not turn on - it doesn't respond to the power button. It had been shut down for a few days, I turned on the power and it booted up as normal, the desktop appeared and I was about to open the web browser when it suddenly went dead; the screen immediately turned off with no warning or noise. There is no fan or disk noise coming from it when the power lead is plugged in, just a very, very faint electronic hum from inside.
From reading various webpages, it seems possible that the power supply could have failed. Is there a simple way that I can diagnose this before deciding whether to attempt to replace it myself or not? I understand that there should be some diagnostic LEDs which could help identify a problem - I've removed the surround from the iMac and peeled back the black EMI film below the display but I'm not sure for what or where I should be looking (they seem to be easier to find on the 17" models).
Whilst I know a repair might not be cost-effective on such an old machine, I have 220GB of photographs, documents and music on it - none of which is backed-up - so I am very keen to get it working and backed-up as soon as possible.
Could anyone suggest how to diagnose the problem?
iMac G5