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iMac G5 crashing - hardware?

D

Dave00

macrumors 6502a
Original poster
Dec 2, 2003
884
119
Pittsburgh
Kind of a weird iMac problem. I have an original iMac G5, System 10.3.9, with built-in airport & bluetooth. In the middle of booting (during the spinning logo part of the cycle), the iMac just shuts off. Boom, like the power was cut. So I tried booting with the shift key held down, boots into Safe Mode without problem, but then I can't access my bluetooth keyboard/mouse, so I have to shut down using the power button on the back of the iMac. Now here's the weird part. After rebooting, everything works fine. But if I repeat the process - shut down normally, reboot - I get the catastrophic crash again. Not until I boot into Safe Mode, then reboot using the power key, does everything go back to normal.

With the abrupt loss of power, I'd have to think there was a hardware issue, but I can't explain the workaround noted above. Any ideas?

Thanks,
Dave

ps - since when did the term "Safe Mode" come to the mac? Last I tried to troubleshoot (years ago) it was always "extensions off."
 
"Safe Mode" came along with OSX.

Powering down in the process of starting up is a fairly common symptom of an unbootable Mac (although why it becomes bootable after a Safe Mode start is mysterious). If it were me, I'd reboot into Single User Mode and run fsck. If you don't know how that's done, restart on the install/restore DVD and run Disk Utility. The bottom line is, find out if your hard drive is in good shape before doing anything else.
 
Yeah, a disk check is always a good idea, and if you're a nerd like me then you might even enjoy it. Here is an Apple document on Safe Mode.


  • It forces a directory check of the startup volume.
  • It loads only required kernel extensions (some of the items in /System/Library/Extensions).
  • In Mac OS X 10.3.9 or earlier, it runs only Apple-installed startup items (some of the items in /Library/StartupItems and /System/Library/StartupItems - and different than login items).
  • Mac OS X 10.4 Tiger only: It disables all fonts other than those in /System/Library/Fonts .
  • Mac OS X 10.4 Tiger only: It moves to the Trash all font caches normally stored in /Library/Caches/com.apple.ATS/(uid)/ , where (uid) is a user ID number such as 501.
  • Mac OS X 10.4 Tiger only: It disables all startup items and any Login Items.


From this we should be able to narrow down the list of possible causes. What startup items do you have?
 
mad jew said:
Yeah, a disk check is always a good idea, and if you're a nerd like me then you might even enjoy it. Here is an Apple document on Safe Mode.
[...]
From this we should be able to narrow down the list of possible causes. What startup items do you have?
Click to expand...

Startup items, I'm not sure, although I know I haven't installed or updated anything recently, so I wouldn't think it'd be a conflict there. If Safe Mode does a directory check, then i wonder if there's something corrupt there that gets fixed every time I startup in safe mode, and carries over to the first restart after that. Is there any way to startup in safe mode and still use bluetooth? From my old days as "the mac guy" at my undergrad institution (my how technology changes and you can go from expert to novice) there were a number of things you could press to boot into different modes - "C" key got you a CD boot, for instance.

Dave
 
I dunno how to get Bluetooth in Safe Mode, but I know that C at startup still boots you from the CD/DVDs. If you don't have separate Apple Hardware Test discs then you can boot the OSX discs and hold D to get the tests going all the same. This might show us something.

Also, there's a feature called Archive & Install which basically reinstalls your system but lets you keep your settings. IJ Reilly will probably chew my balls off for mentioning it, but it's worth a look in all the same in my opinion (as lowly and irrelevant as it is).

Have you tried the disk check yet? :)
 
mad jew said:
I dunno how to get Bluetooth in Safe Mode, but I know that C at startup still boots you from the CD/DVDs. If you don't have separate Apple Hardware Test discs then you can boot the OSX discs and hold D to get the tests going all the same. This might show us something.

Also, there's a feature called Archive & Install which basically reinstalls your system but lets you keep your settings. IJ Reilly will probably chew my balls off for mentioning it, but it's worth a look in all the same in my opinion (as lowly and irrelevant as it is).
Click to expand...

Ahem. No thank you. :eek:

If I read the description of the problem correctly, he can do a standard reboot after a safe mode boot, which is an odd one. If such a thing happened to me, I'd be very interested to know if my hard disk had any problems, before I tried anything else, especially a reinstall. You know my policy on reinstalls in general, but I'd be even more adamantly opposed in this case because a person could very well be trying to install OSX on a drive with a hosed directory. Not a good thing. First things first...
 
Yeah, sorry if I didn't make that clear. Definitely check the drive first.


  1. Check the drive using the OSX discs.
  2. Repair if necessary.
  3. IJ Reilly can now chew my balls, or those of a close friend.
  4. Back everything up via the post-Safe Mode boot.
  5. Start thinking about an Archive & Install.
 
I went into Disk Repair and repaired permissions, which did change some files. Should I restart using the install DVD (will this allow me to use my bluetooth only keyboard? - if I can't then it'd be hard to run any utilities).

I am reluctant to use fsck because of my general uneasiness with running command-line utilities I don't understand (been burned with this a number of times back in the day when I used to know how to run shell scripts.) Also, I'm not sure how to go into single-user mode.

Any other thoughts? (And thanks for the help thus far.)

Dave
 
Single User Mode is painless. The steps:

Boot holding down the cmd-s keys. Hold them down until you see white characters on a black screen. When the scrolling text stops, at the command line, type:

fsck -f [including the space, return]

If anything is repaired (wait a few minutes), run fsck again until no repair is reported. Then, at the command line, type:

reboot [return]

That's it!
 
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