Apple imac 20 inch early 2008 User Manual

							iMac (20-inch Early 2008)  Take Apart — Optical Drive Fan 111
Replacing the Optical Drive Fan
Lower the fan onto the guide posts in the rear cover. 1. 
Connect the fan cable to the logic board.2.  
3.  
						

							iMac (20-inch Early 2008)  Take Apart — Optical Drive Fan 11 2
Connect the optical drive cable connector to the audio board and replace the metal cable 4. 
clip over the cable connector. Make sure the straight side of the clip is facing the audio 
board.
Replace the right speaker if it was removed.
5. 
Replace the display panel6. .
Replace the front bezel.
7.  
Clean and replace the glass panel8.  . Note: This step is very important. Follow the procedures 
to ensure the glass is clean and free of particles.
Replace the access door
9. . 
						

							iMac (20-inch Early 2008)  Take Apart — CPU Fan 113
CPU Fan
Tools
No tools are required to remove the cpu fan.• 
Preliminary Steps
Before you begin, remove the following:
A
• ccess door
Glass pane
• l
F
• ront bezel
LCD display pane
• l
L
• eft speaker
Part Location 
						

							iMac (20-inch Early 2008)  Take Apart — CPU Fan 11 4
Removing the CPU Fan 
1. Disconnect the CPU fan cable from the lower left corner of the logic board.
Lift the fan off the guide posts on the rear housing. 2.   
						

							iMac (20-inch Early 2008)  Take Apart — CPU Fan 11 5
Replacing the CPU Fan
Lower the fan onto the guide posts in the rear housing. Push it down snug onto the posts.1. 
Connect the CPU fan cable to the third connector from the left, in the lower left corner of the 2.  
logic board.
Replace the left speaker3. . 
Replace the display panel
4.  .
Replace the front bezel.
5. 
Clean and replace the glass panel6.  . Note: This step is very important. Follow the procedures 
to ensure the glass is clean and free of particles.
Replace the access door
7.  . 
						

							iMac (20-inch Early 2008)  Take Apart — Power Supply, AC/DC 11 6
Power Supply, AC/DC
Tools
Torx T10 screwdriver• 
Preliminary Steps
Before you begin, remove the following:
A
• ccess door
Glass Pane
• l
F
• ront bezel
LCD display pane
• l
Part Location 
						

							iMac (20-inch Early 2008)  Take Apart — Power Supply, AC/DC 11 7
Removing the AC/DC Power Supply 
WARNING:  HIGH VOLTAGE: The AC/DC power supply PCB remains powered up whenever the 
system is plugged in, whether or not the system has been turned on. Use extreme caution 
when troubleshooting the system with the front bezel removed. 
Don’t work alone. In the event of an electrical shock it is important to have another 
• 
individual present who can provide assistance.
Keep one hand in your pocket when working on any iMac system that is plugged in. 
• 
This will help ensure that your body does not provide a path to ground in the event 
that you accidentally make contact with the line voltage.
Don’t wear jewelry, watches, necklaces, or other metallic articles that could present a 
• 
risk if they accidentally make contact with the power supply circuitry. 
Use extreme caution when working around the power supply. The power supply contains 
1. 
a high voltage capacitor that may remain charged for several minutes even when the 
computer is unplugged. Never touch the leads on the top side of the power supply, 
especially the capacitor leads located near the warning sign.  
Note: If the computer is shut down by pulling the power cord, allow the power supply a 
good 2-3 minutes to discharge the capacitors before handling it.  However, if you select “Shut 
Down” via the Apple menu, the computer will discharge the power supply capacitor almost 
immediately.
Using a Torx T10 
2.  screwdriver, remove the four screws from the AC-DC power supply board.  
Replacement Note: Install the machine screws on the right side and the self tapping screws 
on the left side.
922-6800
922-6842 
						

							iMac (20-inch Early 2008)  Take Apart — Power Supply, AC/DC 11 8
After removing the screws, lift the power supply up a bit and disconnect the DC power 
3. 
supply cable and the small two-pin ground connector in the top left corner.
Disconnect the AC power inlet cable tucked neatly between the right pressure wall (black 4.
 
plastic piece along the right side of the power supply). 
Lift the power supply from the rear housing.5.  
						

							iMac (20-inch Early 2008)  Take Apart — Power Supply, AC/DC 11 9
Replacing the AC/DC Power Supply
WARNING: The AC/DC power supply PCB remains powered up whenever the system is 
plugged in, whether or not the system has been turned on. Use extreme caution when 
troubleshooting the system with the front bezel removed.  Don’t work alone. In the event of an electrical shock it is important to have another 
• 
individual present who can provide assistance.
Keep one hand in your pocket when working on any iMac system that is plugged in. 
• 
This will help ensure that your body does not provide a path to ground in the event 
that you accidentally make contact with the line voltage.
Don’t wear jewelry, watches, necklaces, or other metallic articles that could present a 
• 
risk if they accidentally make contact with the power supply circuitry.  
1. Make sure the right pressure wall is in place. If it was removed, slip the pressure wall over the 
two posts on the chassis and replace the two machine screws. 
						

							iMac (20-inch Early 2008)  Take Apart — Power Supply, AC/DC 120
2. Route the AC inlet cable under the pressure wall as shown.
Connect the AC inlet cable to the power supply and tuck the connector under the bottom 3. 
right corner of the power supply.