iMac does not boot, wheel spins forever

[ChrisA]

Looks like I have a broken iMac. First I unplug all the USB/FW devices I have except the keyboard. I hit the power switch, I get the "chime" sound, grey screen then grey Apple logo and then the little circle icon that rotates. It will rotate like that for hours so I turn it off.

So my question is What is the Mac doing while the wheel is spinning? Looking for a boot device? Then why not say "can't find boot device?" I think the problem might be even more basic than a dead disk drive. How to figure this out?

 

[vlasciar]

boot on safe mode?

Try to boot on safe mode and see if that will access the main harddrive.

To boot in safe mode, turn on your computer and immediately hold "Shift" button, and once the grey screen appear with the spinning wheel you could release the "Shift" button.

In safe mode, go to your Application/Utilities folder and run Disk Utility and select your harddrive and run "Repair Disk Permissions"

Usually the procedure above will fix the iMac on my workplace.

Good Luck!

 

[steelrod]

i have the same problem in my imac

yet i cant get into safe mode or anything, ive tried diferent keypresses

it wont even read my cd all the player does is make a noise and kicks out the cd, so cant try and re-install

thanks

percy

 

[Kasalic]

Looks like I have a broken iMac. First I unplug all the USB/FW devices I have except the keyboard. I hit the power switch, I get the "chime" sound, grey screen then grey Apple logo and then the little circle icon that rotates. It will rotate like that for hours so I turn it off.

So my question is What is the Mac doing while the wheel is spinning? Looking for a boot device? Then why not say "can't find boot device?" I think the problem might be even more basic than a dead disk drive. How to figure this out?

The grey spinning icon is the Kernel stage of mac startup. The official troubleshooting technique is to start in Safe Mode (hold down SHIFT whilst booting). If this allows you to get to the login window then it is likely that a third party Kernel Extension is causing the issue. You would then need to boot into Verbose mode (CTRL + V) and wait for the text to stop scrolling up. This should then tell you which KEXT is causing the issue (it will be the last item on screen), and you can then boot into Single User mode (CTRL +S) and move the offending KEXT to a quarantine folder.

If Safe Mode doesn't work then you are looking at an OS reload.

 

[ChrisA]

The grey spinning icon is the Kernel stage of mac startup.....

Thanks. This was what I needed to know. I had assumed it was a much earlier stage.


I miss the days when all computers first booted to a ROM based monitor. You then had good diagnostic tools even if major parts of the machine had failed. Remember Sun's "openboot" Forth prompt?

 

[Kasalic]

Thanks. This was what I needed to know. I had assumed it was a much earlier stage.


I miss the days when all computers first booted to a ROM based monitor. You then had good diagnostic tools even if major parts of the machine had failed. Remember Sun's "openboot" Forth prompt?

Never played with any of that stuff I'm afraid. I've seen two or three Mac OS X installs go belly up due to a corrupt system Kernel in the last few months, and in a couple of cases I've spent an hour or so trying to replace the file remotely using Target Disk Mode only to end up backing up and reinstalling. I charge £45 per hour +VAT so it quickly becomes more economical for the end user to reinstall.

Hope you get it sorted quickly.