View Full Version : Power Mac G5 won't turn on with board switch?
April 5th, 2012, 07:21 AM
I have a Power mac G5 1.6Ghz model, and 2 days ago it was working fine but the drive had bad sectors and replaced it with a new one. Now it won't switch on with the switch on the board. I reset PRAM, changed battery and RAMS. Out of furstration I press the apple monitor power and I hear the chime. But no light on the LED near the power switch and it won't switch on if I try the front power button. Can you guys help?
April 5th, 2012, 07:41 AM
Have you tried resetting the PMU?
April 5th, 2012, 07:49 AM
@ElDiabloConCaca: Yes I tried that but still it won't turn on. When I press the power button from my screen I hear the chime and then it shows a folder with a question mark. But the power on the box does nothing and it is connected to the board properly and tight. I am really getting nervous now.
April 5th, 2012, 07:49 AM
Just so I understand - your PowerMac G5 will not turn on when you press the front panel power button. Is that correct?
But, it will turn on when you press the power button on your Apple display...
Is that also correct?
And, you also say that when the PowerMac does turn on, you still don't see any light near that front panel power button.
And, is that also correct?
Does that front panel light ever come on, or start flashing?
Did your PowerMac work to get OS X installed on your new hard drive?
If yes, does your PowerMac boot and run OK now, except for the power button?
The ? flashing on your screen means that there's no boot system, so I assume that you have not installed OS X yet. If you CAN boot to your installer after getting power through the display power, then you should be able to install OS X.
Last question - What did you mean by the 'board switch?"
Do you mean a power button on an old Apple USB keyboard?
That can't work - your G5 is too new for that.
April 5th, 2012, 07:59 AM
@Deltamac: yes, when I press the front panel power button it won't turn on, but turns on via the apple display power button. There is not any type of light at all in the front panel. I was just about to install Tiger OS X on the new hard drive, so no there wasn't any OS yet. And when I press "Option" or "C" to boot from disc nothing happens but the folder icon appears. And when I said (the board switch) I meant the front panel power button.
April 5th, 2012, 09:31 AM
Check carefully inside directly behind the front panel - there's a short cable (cased in a black braid) which connects from the front panel to the logic board. It's only about 3 or 4 inches long. Make sure that's connected securely on both ends.
Make sure your USB keyboard is plugged into one of the rear USB connectors, because that same little cable also connects the front USB connectors (and the front connectors may be dead, too!) Then, try to restart while holding the Option key.
April 11th, 2012, 03:48 AM
Sorry for the late response, I managed to install Tiger OS X and it works fine.
But still powers with the apple display switch, I checked behind the front panel and the cable is connected securely and everything you guys suggested did not resolve.
I don't know if this may help but what I noticed: when I press the power switch on my tower and the one on the screen at the same time there front panel shows a white light but as soon as I release the button (front panel) it goes off again. But the mac still runs. Could there be a solution to this?
April 11th, 2012, 07:01 AM
Yes, use the power button on your display, if that works.
It's likely that the front panel board has failed. The power button is also separately replaceable. You could search for those at one of the sites that sells replacement parts. Another method would be to find a complete replacement case, or a complete PowerMac G5 just for spare parts.
April 11th, 2012, 07:23 AM
The USB, Firewire and headphones jack work perfectly though...
So you don't think this will be an issue or see the machine fail in the near future?
Plus I don't like the Apple CRT display I have bought 2 LED monitors but it wont power with them. I will look around for mac spares and see what happens.
April 11th, 2012, 07:43 AM
Right! - it will be difficult if you lose the only method that you still have for powering your G5.
The power button plugs in to the front panel board, and there is some electronics on that board which provide that power on signal - so other functions can work, but the power button does not.
April 11th, 2012, 08:40 AM
I've seen this same behavior on at least a couple of occasions with old G4 towers where the cinema display power button will power on the machine but not the front panel board button. It's almost like they become trained to only power on one way? It was a while ago and many repairs ago and I can't remember what happened with those machines? But as it turned out the customers didn't want to spend the money to figure it out as long as the machine still powered on.
April 11th, 2012, 08:54 AM
djackmac: I am worried that this might get worse and make the machine to refuse to power at all. And this situation forces me to use the CRT monitor that takes a lot of space on my desk, but hey what can I do?
Do you think it may mess things up in future? It's a very unusual scenario and can't seem to get any solutions besides replacing parts.