Apple imac 20 inch late 2006 User Manual

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 161
 
 
 
  
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 162
Open the Energy Saver System Preferences and temporarily set the display to sleep after 
1.  
one minute. Set the computer to sleep after ten minutes. Once the Energy Saver preferences 
have been set, wait for the display to go to sleep.
Wake the display from sleep and observe the display. Does the image on the display 
2.  
shimmer or fill with horizontal or vertical lines when waking from sleep?
Ye s : Replace the main logic board
No : Continue troubleshooting using appropriate symptom charts
Note: To ensure optimal image quality the system should be left unplugged for approximately 
two hours after reproducing this failure. Once the logic board has been replaced wait until the 
system has been off for approximately two hours before powering up the system. Be sure to 
restore the customer’s Energy Saver preferences to their previous values before returning the 
system to the customer. 
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 16 3
Display
The display does not remain in its intended position when tilted.
The iMac (20-inch Late 2006) display should move and stay in an intended position for it’s range 
of motion.Verify that the display is not keeping position.
1.  
Verify that the computer stand is not propped up in the rear (resting on its power cord, for 
2.  
example).
Verify that the work surface is also flat as in relation to the floor. A tilted work surface (such 
3. 
as a drafting table) could cause the display not to keep position as described above.
Remove all the interior components and replace the clutch mechanism, part 922-7002. If 
4.  
necessary, cover this component with a CS Code 
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 16 4
When displaying a single color over the screen area, the LCD panel shows one or more pixels 
that are not properly lit
Active-matrix LCD technology uses rows and columns of addressable locations (pixels) that 
render text and images on screen. Each pixel location has three separate subpixels (red, green, 
and blue) that allow the image to be rendered in full color. Each subpixel has a corresponding 
transistor responsible for turning the subpixel on or off.
There are typically millions of these subpixels on an LCD display. For example, the LCD panel used 
in the Apple Cinema HD display is made up of 2.3 million pixels and 6.9 million red, green, and 
blue subpixels. Occasionally, a transistor does not work perfectly, which may result in the affected 
subpixel being turned on (bright) or turned off (dark). With the millions of subpixels on a display, 
it is quite possible to have a low number of faulty transistors on an LCD. Therefore, a certain 
number of subpixel anomalies is considered acceptable. Rejecting all but perfect LCD panels 
would significantly increase the retail price for products using LCD displays. These factors apply 
to all manufacturers using LCD technology—not just Apple products.
To determine whether or not the display has an acceptable number of pixel anomalies, follow the 
steps below:
Set the display image to one of the following colors: all-white display, all-red display, all-green 
1.  
display, or all-blue display.
Using a jeweler’s loupe, pocket microscope, or other magnifying device, identify and count 
2.  
each subpixel anomaly:  
• Bright subpixel anomaly = subpixel that is always on 
• Dark subpixel anomaly = subpixel that is always off 
Important: 
3.  Check the number of subpixel anomalies with the following chart:  
 
LCD Size 
(inches) Acceptable Number of Subpixel 
Anomalies Replace the Display
Bright Dark Both Bright Dark Both 
17 to 20 up to 4 up to 6up to 85 or more 7 or more9 or more
If the number of subpixel anomalies exceeds the acceptable number listed in the chart, 
4.  
replace the LCD panel.
If the number of subpixel anomalies is acceptable, explain to the customer that the pixel 
5. 
anomalies are within specifications, and no repair is necessary. 
Important:  Do not release the specifications to customers. Instead, inform them that a 
certain number of subpixel anomalies is considered acceptable, and these factors apply to all 
manufacturers using LCD technology—not just Apple products. 
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 165
Hard Drive
Flashing question mark, or an alternating question mark and Mac OS (face or a 
folder)
Note: When troubleshooting hard drive problems it is a good idea, if possible, to back up any 
important data. Some troubleshooting steps may require erasing the contents of the hard drive.Boot from the system CD that came with the computer, and open Disk Utility. Does the hard 
1.  
drive show in Disk Utility? 
Yes: Run Repair Disk and Repair Permissions to correct any directory and permissions issues. 
Go on to Step 2.  
No: Go to Step 3.
Did Disk Utility successfully repair directory or permissions? 
2.  
Yes: Restart the computer to the hard drive. Go on to Step 3.  
No: Go to Step 3.
Did the computer successfully start to the internal Hard Drive? 
3. 
Yes: Run Apple Hardware Test version 3A108 or later for this machine and return to the 
customer if it passes.  
No: Boot the machine to Apple Hardware Test, version 3A108 or later, or to Apple Service 
Diagnostic for iMac, version 3S106 or later.
Did the machine successfully boot to the Diagnostic? 
4.  
Yes: Run the test suites.   
No:  Make sure you’re using the correct version of the Diagnostic, and that the disc is able to 
boot another machine that it supports. If so, then try booting from an external optical drive. 
If this is successful, you should replace the optical drive and retest the machine booting to 
the diagnostic disc.   
Did the tests pass? 
5. 
Yes: Reinstall the System Software that came with the computer and test.   
No: Replace the component (s) indicated by the test results.  
Hard Drive Issues
Note: The following information is for Intel-based and PPC Macintosh drive compatibility
Drives to be used in booting Intel-based Macintosh hardware should be formatted and 
• 
partitioned with an Intel-based Macintosh disk utility running on Intel-based Macintosh 
hardware. That should ensure you get the correct default partition map and structure for 
reliable booting.
Intel-based Macintosh CPUs in Target Disc Mode will only mount on PPC machines running 
• 
Mac OS X 10.4 or later, and may show one contiguous partition rather than separate 
partitions on the host machine.
Always make sure to use the OS that came with the machine if you need to reinstall software 
• 
(ask the customer for the discs if necessary), and the diagnostics specifically designated for 
that hardware. 
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 166
System hangs during normal startup process
Boot from the system CD that came with the computer. Use Disk Utility to verify the hard 
1.  
drive.
Using Disk Utility, reformat the hard drive.
2.  
Check all cable connections to and from the hard drive.
3. 
Replace the hard drive data cable.
4.  
Replace the hard drive.
5. 
Replace the logic board.
6.   
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 16 7
Optical Drive 
CDs or DVDs don’t show up on the Desktop.
Select Preferences from the Finder menu and make sure the option to show CDs, DVDs and 
1.  
iPods is checked: in the General window as shown below.   
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 168
Select System Preferences from the Apple menu and open the CDs & DVDs preferences 
2.  
window. Make sure that audio CDs are set to launch iTunes and movie DVDs set to launch 
DVD Player when those media are inserted, as shown below.  
Check that the drive can read discs normally. Insert an audio CD and check whether it shows 
3. 
up on your desktop or launches iTunes.  
Does the audio CD mount on the desktop or in iTunes? 
Yes: The drive seems to read CD discs okay. Go on to Step 4.  
No: Make sure the disc is readable by other computers. Try other CD discs. If none mount or 
no audio CDs launch iTunes, replace the optical drive.”
Eject the audio CD and insert the iMac Software Install and Restore DVDs that came with the 
4.  
customer’s computer, or insert a DVD movie.  
Does this disc show up on the desktop, or does the movie launch DVD Player?  
Yes: The computer is reading CD and DVD media. This may be related to a specific disc or 
discs the customer is using and you should examine those discs.  
No: The optical disc is reading CD media, but not DVD media. Try other DVD discs. If none 
mount or movie DVDs do not launch DVD Player, replace the optical drive flex cable.
If after replacing the optical drive flex cable the drive still won’t mount any optical media, 
5. 
replace the optical drive. If the issue persists, then replace the logic board.  
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 16 9
The computer won’t burn discs.
Check whether the drive can read CDs and DVDs normally. Perform the steps above for “CDs 
1.  
or DVDs don’t show up on the Desktop.”
Try a test burn by creating a Burn Folder, as follows.  
2.  
• In the Finder, choose “New Burn Folder” from the File menu.  
 
• Open the Burn Folder, drag an item inside for testing, and click “Burn” in the upper right 
corner of the window.  
  
• When prompted, insert a blank disc and follow the dialog instructions.  
Does the disc burn successfully (problem solved), fail with an error, or is the disc ejected?
If the disc fails to burn with an error, check for these error messages.  
3. 
Unknown Error -2147352480. See Knowledge Base article 25480 and 25750 for more 
information.  
Buffer	underrun	error. 	See Knowledge Base articles 25480 and 25750 for more information.  
Unknown Error. If you see “Unknown Error” without “-2147352480”, you will want to see 
Knowledge Base article 152224 for more information.  
If the blank disc is ejected, try another blank disc. If the issue persists, try another brand and 
4.  
speed of blank media; if you’re using blank CD media, see if this happens with blank DVD 
media. If the drive consistently rejects all blank media, or only rejects blank CD media while 
accepting blank DVD media or vice versa, replace the optical drive flex cable and test.  
Does the drive successfully burn to disc after replacing the optical flex cable? 
Yes: Problem solved.   
						

							iMac (20-inch Late 2006) Troubleshooting — Symptom Charts 170
No: Replace the optical drive. Does it burn correctly now? 
 
Yes: Problem solved.  
  No: Replace the logic board.
Discs won’t insert.
Is there a disc already in the drive? 
1.  
Yes: Eject the disc before inserting another. Refer to Knowledge Base article 106752, 
“Macintosh: How to Eject a Disc When Other Options Do Not Work”. If none of these options 
will eject the disc, you may have to disassemble the drive to recover the disc. See Knowledge 
Base article 86382 - Macintosh: How to Remove a Stuck Disc From a Slot-Loading Drive.  
No: Reseat the optical drive. Perform the “Optical Drive” procedure in Take Apart to reseat the 
drive in the mounting aperture and reconnect the optical flex drive cable connector.
After reinstalling the optical drive, can you now insert a disc? 
2.  
Yes: Issue resolved. Run diagnostics and return the system to the customer.   
No: Replace the optical drive flex cable.   
Yes: Problem solved. Run diagnostics and trying inserting a disc again.
After replacing the optical drive flex cable, can you insert a disc now? 
3. 
Yes: Issue resolved. Run diagnostics and return the system to the customer.   
No: Replace the optical drive.