How do I diagnose a power supply?

One day all was well and the next the machine would not turn on. There is no sound at all -- no chime -- no fans -- nothing.

I opened the computer and plugged the power cord in. There are 4 diagnostic lights on the motherboard. Only light #1 is on. This indicates that the motherboard sees the power supply. The Apple guides show this area containing 2 buttons on the motherboard. This particular G5 only has one button. The Apple description says to press the upper button to restart the computer (with the back off) I only have one button and it seems to do nothing. However, I did push the button -- then I put the back on the machine and tried using the start up button. Nothing happened.

I cannot find another button to push on the motherboard.

Because the one diagnostic light comes on may mean the power supply is functioning. (I thought that was going to be the problem before I started this project.)

What is next?

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Deck the Halls
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Diagnostic light no 1 means trickle power is supplied. That happens when you put the cord in. When you press the power button light no 2 should come on, otherwise your power supply neede attention/replacement. No 3 and 4 refer to the video subsystem.

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When you say "press the power button" is where I get into trouble. I can not find a power button except on the case --- which I means I must put the back on the machine and then cannot see any lights at all. There should be a power button inside the machine -- with the case open --- but I cannot find that button. Every reference shows 2 buttons but my machine only has one button. Should I try shorting across the wires that show in about the proper area?'

Thank you for considering my problem.

Jim

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teeitup98 will be eternally grateful.
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