2006 Intel iMac Startup Command Key

2006 iMac Intel



Recently I repaired a 20-inch 2006 iMac and was reminded of how much things have changed since the arrival of the Intel-based iMacs. Repairing or upgrading an iMac got a little more complicated. Apple used to make it possible for you to upgrade the RAM and hard drive of your iMac with relative ease, even with the 2002 “Snowball” iMac. It might have been somewhat of a jigsaw puzzle but it was doable, even for someone working on their first iMac. Taking apart an iMac (2006) model now requires quite a bit of nerve and careful skill to get at the hard drive, now mounted behind the screen and surrounded by flimsy heat shields. RAM is something you can still do yourself, except you need strong fingers. What hasn’t changed are the number of Startup key combinations you need to remember when working on your Mac regardless of the model or operating system.


Startup Key Combinations

I have listed startup key combinations that you can use to at startup on all Intel-based Macs. These are the basis of most repairs and troubleshooting paths and it is good to know them.

Press/Hold During Startup Description
C Start up a bootable CD or DVD such as a Mac OS X Install disk or repair utility.
D Start up in Apple Hardware Test (AHT) with the Install Disk 1 is in computer
Option+Command+P+R Reset Nonvolatile Memory (NVRAM).
Option Start up into System Manager. You can select and start up from any Mac OS X volume or CD/DVD disk.
Eject, F12, or mouse/click or Trackpad Button Eject any removable media, such as a optical disk.
N Start up from a compatible Network Server (NetBoot)
T Start up in FireWire Target Disk Mode.
Shift Start up in Safe Boot mode and temporarily disable login items.
Command+V Start up in Verbose Mode
Command+S Start up in Single-User Mode. You can run disk utility from here by typing “/sbin/fsck -fy”
Option+N Start up from a Network Server (NetBoot) using the default boot image.



Locating the iMac G5 logic board SMU

iMac G5 Reset Button


Locating the iMac G5 logic board SMU


Recently a series of 20-inch iMac G5s I manage had either their power supply or graphics card fail due to a bad iMac G5 logic board controller. In one case I was able to reset the System Management Unit (SMU) and to correct the power supply issue I was having. The iMac G5’s advanced System Management Unit (SMU) manages the thermal and wattage conditions, while at the same time keeping the iMac’s noise to a minimum by regulating the speed of each fan. The SMU reset button (shown below) is similar to the PMU button on previous iMac, G4 and G3 computers.

The SMU supports the following functions:

  • Initial configuration of system clocks.
  • All power button and environmental user events.
  • Controls fan speed (RPM).
  • Provides processor Mode Ring and thermal data store.
  • Monitors processor temperature and power consumption.
  • Monitors VRD10-compliant processor power supply digital interface.




Resetting the SMU

Resetting the SMU will not resolve issues when your Macintosh is unresponsive – in these situations, restarting your Mac will generally resolve the issue. If your Mac isn’t responding, perform these steps one at a time, in this order, until the issue has been resolved:

  1. 1. Force Quit (Option-Command-Escape If Applications are unresponsive If Applications are unresponsive).
  2. 2. Restart (Control-Command-Power).
  3. 3. Force Shut Down (press the power button for 10 seconds).

[Note: Resetting the SMU does not reset the PRAM. ]

iMac G5 Reset SMU: No longer termed iMac PMU reset button

Resetting the SMU can resolve some computer issues such as not starting up, not displaying video, sleep issues, fan noise issues, and so on. If your Macintosh still exhibits these types of issues even after you’ve restarted the computer, try resetting the SMU. To reset the SMU on an iMac G5:

  1. 1. Turn off the computer by choosing Shut Down from the Apple menu, or by holding the power button until the computer turns off.
  2. 2. Unplug all cables from the computer, including the power cord.
  3. 3. Wait 10 seconds.
  4. 4. Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer.
  5. 5. Let go of the power button.
  6. 6. Press the power button once more to start up your iMac.

The original iMac G5 (2005) model has a small button on the main logic board next to the SMU, allowing you to reset both the SMU with the back cover removed and start up when pressing this button.


Macintosh Problems Finding Results

I recently came across two completely unrelated installations of Mac OS X 10.5.6 where Spotlight had failed to index any new searches and was either holding onto a previous index or contained nothing at all. If you’re encountering Mac Spotlight problems, you might find the following useful.

The two macs I was dealing with were a 24 inch iMac – Intel Core 2 Duo 2.93GHz with 4GB RAM and 640GB hard drive installed. Spotlight seemed to be working properly with the iMac. You could perform a search and find a file, BUT if the file was newer it would not find it. The other was a Xserve with two 2.66GHz Quad-Core Intel Xeon Nehalem with 3GB RAM, 160GB Hard Drive installed and had a Promise VTrak E-Class RAID subsystems attached via Fiber Channel. I installed this Xserve out of the box with Mac OS 10.5.5 installed and updated it to Mac OS 10.5.6. Once the XServe was configured I attached it to the Promise VTrak subsystems and began transferring the companies archive files to it. After this was complete I began searching with Spotlight to see if I missed anything. I found that spotlight worked locally on the first and second Hard Drive but failed when asked to search the Promise VTrak.


There are two ways of handling this type of problem, either through the System Preferences or Terminal. Before starting either option please remember to always REPAIR PERMISSIONS before starting. The System Preferences route is mainly for those who have not used Terminal before and want to use something that is already part of the Mac OS 10. Simply launch System Preferences and Click on Spotlight. Once open, click on the Privacy Tab and then on the “+” (plus) button and add the volume you are trying to index. Wait a few minutes (5-10) and select the volume again on the Privacy Tab and click on the “-” minus button to remove it again. This will force Spotlight to perform a clean re-index of the volume.

In both cases I used the mdutil command in Terminal to resolve the issue. If you are not familiar with mdutil, its the command used to manage the metadata stores of mounted volumes that are used by Spotlight. The mdutil options include:

-p Publish metadata.

-i (on|off) Turn indexing on or off.

-E Erase and rebuild index.

-s Print indexing status.

-a Apply command to all volumes.

-v Display verbose information.

To perform this command you will need to launch Terminal and type the following to turn off indexing:

username$ sudo mdutil -i off /Volumne
Password: (your password here)

With Terminal still open, type the following to get an index of the volume you are trying to repair spotlight on.

username$ cd/
(This gets you into the volumne structure)
username$ sudo ls
(This give you an index of all the hidden files on your Hard Drive)

You should see something similar to the following:

.DS_Store      Library      home

.Trashes      mach_kernel

.fseventsd       Shared Items      mach_kernel.ctfsys

.hotfiles.btree     System      net

.vol       Users      private

Applications      Volumes      sbin

bin      tmp      cores      usr

dev      var

Groups      etc

The two files you are after here are the .metadata_never_index and .Spotlight-V100. In one of my cases the .metadata_never_index was missing as in the example above. Don’t freak out if it is. The next two commands will remove these two files.

username$ sudo rm -r /.Spotlight-V100
username$ sudo rm .metadata_never_index

the sudo rm of the .metadata_never_index might return the following as mentioned about. Not to worry – that’s why we are working through these steps to get everything up and running again.

rm: .metadata_never_index: No such file or directory

Now let’s get everything back up and running. Type the following:

username$ sudo mdutil -i on /
/:
Indexing enabled.
username$ sudo mdutil -E /
/:
Indexing enabled.
username$ exit

That should do it. You will see the Spotlight icon in the upper right corner start pulsing a small dot in the center and if you click on it you can find out how long it will take to re-index.

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