iMac G5 vintage SPU

Roberto · 02-16-2013, 10:15 AM

Hi
I have an old iMac G5 vintage that does not turn on. I saw images online of internal power buttons. Mine only has 1 button, but does not have the SPU one. How can I try to switch it on from the internal button?
Thanks!

DeltaMac · 02-16-2013, 10:49 AM

The earliest G5 iMac has two buttons.

If yours has only one button, near the large fan, that is the "other" power button, and not a reset button at all.
You can try an SMU reset, by removing ALL external cords, including the power cord.
Wait 10 seconds.
Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer.
Release the button, then press it again to start your iMac.
You can do this with the back open - the single button is an internal power button.
You should notice the fans start running, and you can watch the row of 4 lights, about 5 cm to the right of the internal power button.

If nothing happens, do any of those lights come on? The first light tells you that the power supply is getting good power from the AC outlet.
After pressing the power button, the second light should appear, telling you that the power supply is supplying 12 volts. Does that #2 light stay on - or immediately go off again?

agentx · 02-18-2013, 04:44 AM

And could be the dreaded bad Capacitors and PSU on that model.
Looking at board lights will tell you ;-)

02-16-2013, 10:15 AM	#1
Roberto Prospect Join Date: Feb 2013 Posts: 1	iMac G5 vintage SPU Hi I have an old iMac G5 vintage that does not turn on. I saw images online of internal power buttons. Mine only has 1 button, but does not have the SPU one. How can I try to switch it on from the internal button? Thanks!

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02-16-2013, 10:49 AM	#2
DeltaMac League Commissioner Join Date: Jan 2002 Posts: 7,954	The earliest G5 iMac has two buttons. If yours has only one button, near the large fan, that is the "other" power button, and not a reset button at all. You can try an SMU reset, by removing ALL external cords, including the power cord. Wait 10 seconds. Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer. Release the button, then press it again to start your iMac. You can do this with the back open - the single button is an internal power button. You should notice the fans start running, and you can watch the row of 4 lights, about 5 cm to the right of the internal power button. If nothing happens, do any of those lights come on? The first light tells you that the power supply is getting good power from the AC outlet. After pressing the power button, the second light should appear, telling you that the power supply is supplying 12 volts. Does that #2 light stay on - or immediately go off again?

02-18-2013, 04:44 AM	#3
agentx Hall of Famer Join Date: Feb 2003 Location: Brighton, UK Posts: 3,807	And could be the dreaded bad Capacitors and PSU on that model. Looking at board lights will tell you ;-)