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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > PowerMac G4 shuts off 5 seconds into the start up

PowerMac G4 shuts off 5 seconds into the start up
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mlancerv
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Jun 29, 2002, 03:25 PM
 
It's 350mhz model and it has 512 mb of RAM running on OS X; the computer repeatedly shuts down every time I start it up. Can anyone help me solve this issue?
     
Leonis
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Jun 29, 2002, 03:29 PM
 
Power Switch problem I think
MacPro 2.66, 5GB RAM, 250GB + 160GB HDs, 23" Cinema Display
MacBook Pro 1.83GHz, 2GB RAM (from work)
MacBook (White) 1.83GHz, 2GB RAM
     
mlancerv  (op)
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Jun 29, 2002, 08:02 PM
 
How can I fix this problem?
     
mlancerv  (op)
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Jun 29, 2002, 08:03 PM
 
How can I fix this problem?
     
rootonimac
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Jun 29, 2002, 08:43 PM
 
How can mlancerv fix this problem!?
     
RBattin
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Jun 29, 2002, 11:50 PM
 
Try these steps until solved:

System shuts down almost immediately after startup
1 Power Macintosh G4 (PCI Graphics): Reset the Cuda chip.
2 Reset the logic board
3 Check the modem connector (J27). If the connector has any
bent pins, replace the logic board.
4 Replace the processor module.
5 Replace the power supply.
6 Replace the logic board.

<small>[ 06-29-2002, 11:51 PM: Message edited by: RBattin ]</small>
     
reader50
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Jun 30, 2002, 11:28 AM
 
It sounds like a problem in the little board behind the front panel buttons. Every modern Mac will shut down if you press and hold the power button for 5 seconds. If the button is not being released when you power on, the system will indeed turn off 5 seconds after starting.

The power button may be slightly misaligned and sticking on the edge of the front panel, this has happened before. You should be able to spot this (the button will be off-center in it's hole), and may even be able to correct it. The button board is held on from behind by a snap-in metal shield, there may also be screws under the shield. If there is any play to work with, you could nudge the board a bit until the buttons are recentered.

The other possibility is that the power button is sticking electrically, a relay or transistor on the button board is not letting go, and is telling the system that the button remains pressed. If so, the only practical solution is to replace the button board.

Finally, a fault on the motherboard or in the power supply could be simulating the same problem. Try the CUDA switch, like RBattin suggests.

My advice: check the button alignment followed by the CUDA switch. If that does not do it, it is time for Apple Support (if the system is in warranty) or a Mac repair shop (if you are out of warranty).
     
mlancerv  (op)
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Jun 30, 2002, 01:44 PM
 
Thanks for the help guys.
     
Dan Szwarc
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Jun 30, 2002, 03:58 PM
 
There could be something wrong internally overloading the power supply and causing a forced shutdown (do macs do this?).

Try disconnecting the CD/DVD, modem, airport, PCI cards, etc. (everything except the HD for booting) and see what happens. If it boots, add them back one by one until you find the culprit. <img border="0" alt="[Hmmm]" title="" src="graemlins/hmmm.gif" />

It's a thought. I had two of them today. <img border="0" title="" alt="[Wink]" src="wink.gif" />
Dan
"I guarantee that I am correct."
(not a guarantee)
     
   
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