Apple imac 20 inch early 2008 User Manual

iMac (20-inch Early 2008)  — Symptom Charts  271
Keyboard is not discoverable
To pair your aluminum Apple Wireless Keyboard with your Macintosh computer, the keyboard 
needs to be in a ‘discoverable mode.’
Note: If you need to put the older Apple Wireless Keyboard in a discoverable mode for pairing, 
see the previous topic.
Follow these steps to put the aluminum Apple Wireless Keyboard in a discoverable mode:
Open the Bluetooth Setup Assistant on your Mac:1. 
For Mac OS X 10.4.10 or late•	r
For Mac OS X...

iMac (20-inch Early 2008)  — Symptom Charts  272
Some keys are working on the Wireless keyboard
If some keys are working, but others behave as if the Caps Lock is “ON”, and the customer was  
using an extended keyboard (with a number pad),  but switched to an Apple Wireless keyboard, 
check the following setting and try the wireless keyboard again.
Turn “Off” Mouse Keys under System Preferences-->Universal Access-->Mouse. •	
Additional Wireless Topics
Can’t wake the computer with the wireless keyboard or...

iMac (20-inch Early 2008)  — Symptom Charts  273
Bluetooth: How to Set Up Your Apple Wireless Mouse
Refer to Knowledge Base document 86468 - Follow the instructions in this document to set up 
your Apple Wireless Mouse.
Bluetooth: How to Se Up your wireless Mighty Mouse
Refer to Knowledge Base document 303921 - Follow the instructions in this document to set up 
your Apple Wireless Mighty Mouse. 

iMac (20-inch Early 2008)  — Symptom Charts  274
Error Beep(s)
Power On Self Test (POST) Tones
Intel-based Mac computers such as the iMac (20-inch Mid 2007) rely on a combination of tones 
and blinking LEDs to display Power On Self Test (POST ) error codes.
If the computer detects out-of-specification or no SDRAM or the RAM installed does not • 
meet the appropriate specifications, the screen will remain black but the computer will beep  
This error condition may be due to physically damaged RAM,...

iMac (20-inch Early 2008) 
 — Symptom Charts   275
USB
USB port is not recognizing known devices
Please unplug all of your USB devices from your iMac except your Apple Keyboard and Apple 1. 
mouse.
Now plug your device directly into the back of your iMac. Does it work as expected now? 2.  
 
Yes: Your device works when plugged directly into the computer. This indicates a conflict 
with one of the other USB devices. You can test by gradually adding your devices back and 
seeing where the issue occurs,...

iMac (20-inch Early 2008) 276 

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iMac (20-inch Early 2008) 

iMac (20-inch Early 2008)  Take Apart 278
iMac (20-inch Early 2008)—Upper Exploded View
LVDS Cable
922-8197
LCD Assembly, 20”
661-4671Front Bezel
922-8582
Glass Panel, Cover
922-8514
LCD Temp Sensor 922-8235
Cable, LCD Temp Sensor 922-8234
Clip, Temp Sensor
922-8183
Power Supply
661-4670, 180W
Hard Drive
661-4632, 250 GB, 7200, SATA
661-4633, 320 GB, 7200, SATA
661-4634, 500 GB, 7200, SATA
661-4635, 750 GB, 7200, SATA
Optical Drive, 8x 
661-4637
Optical Sensor Cable
922-8194
Cable, Optical Flex, DATA...

iMac (20-inch Early 2008)  Take Apart 279
iMac (20-inch Early 2008)—Lower Exploded View
Video Card
661-4672, ATI Radeon HD 2600XT
661-4673, ATI Radeon HD 2400XT
SDRAM Access Door
922-8186
Logic Board
661-4674, 2.4 GHz
661-4675, 2.66 GHz
Cable, 
Ambient Temp Sensor 922-8191
Stand
922-8518 Microphone Cable
922-8190
Mechanism, 20”
922-8221 Camera Cable
922-8189
Rear Cover
922-8515 Cable, AC / DC / 
SATA Power / Inverter
922-8188
IR Board
922-8169
Cable, IR
922-8504
SDRAM 
661-4661 1 GB, DDR2-800, SO-DIMM...

iMac (20-inch Early 2008)  Take Apart — Screw Chart 280
Screw Chart
Screw Chart: Page 1 of 3 
Note: Screws are not to scale.
922-6800
T10
- Logic board to rear cover (4)
-Power supply to rear cover 
(2)
- AC power inlet to rear cover 
(3)
- Cable guide to rear cover
922-6850
T10
Chassis to rear cover (6)
922-8250 
T10
Chassis to rear housing, at 
top of chassis (3)
922-7010 
T6
- Bluetooth card to Logic 
- AirPort card to Logic
- LVDS cable to Logic 
- Audio board
922-8256
T6
IR board to heatsink (2)...