Apple imac 20 inch early 2009 User Manual

iMac (20-inch, Early/Mid 2009) Basics — Overview 11 2010-11-24
Overview
Product Features
The iMac (20-inch, Early 2009) and iMac (20-inch, Mid 2009) computers have the same overall 
look as the previous generation aluminum iMac.  Distinguishing exterior features are Mini 
DisplayPort (instead of mini DVI port) and 4 USB ports (instead of 3) on the rear, and a tapered 
front edge on the stand.
New features:
• Increased processor speed: 2.66GHz
•  Mini DisplayPort
•  4 USB 2.0 ports
•  Increased RAM...

iMac (20-inch, Early/Mid 2009) Basics — Overview 12 2010-11-24
Product Configuration
To confirm the configuration from the Apple menu, choose About This Mac.  The processor 
listing will show the speed of the processor followed by the processor type.  The following table 
shows the configuration at introduction:
FeatureSpecification
Processor 2.66 GHz Intel Core 2 Duo 
6MB shared L2 cache, 1066MHz frontside bus
Memory 2GB (2 x 1GB) 1066MHz DDR3 (optional 4GB, 8GB CTO)
Hard Drive Early 2009: 320GB Serial...

© 2009-2010 Apple Inc. All rights reserved.
 Apple Technician Guide 
Troubleshooting
iMac (20-inch, Early/Mid 2009)   

iMac (20-inch, Early/Mid 2009) Troubleshooting — General Troubleshooting 14 2010-11-24
General Troubleshooting
Update System Software & Firmware
Important: Ensure the correct version Mac OS X and latest software and firmware updates have 
been applied before you begin troubleshooting. Computers sometimes exhibit symptoms that 
indicate the wrong Mac OS X system software is installed. 
Firmware is the name given to software that is written into memory circuits such as flash 
memory, that will hold the...

iMac (20-inch, Early/Mid 2009) Troubleshooting — General Troubleshooting 15 2010-11-24
Apple Service Diagnostic
The correct version for all iMac (20-inch, Early/Mid 2009) is Apple Service Diagnostic 3S131.
Common Reset Procedures
Power On Self Test (POST )
Intel-based Mac computers such as the iMac 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...

iMac (20-inch, Early/Mid 2009) Troubleshooting — General Troubleshooting 16 2010-11-24
Resetting Parameter RAM (PRAM)
PRAM stores certain system and device settings in a location that Mac OS X can access quickly. 
Exactly which settings are stored in the computer’s PRAM varies depending on the type of 
computer as well as the types of devices and drives connected. To reset PRAM:
1.  Shut down the computer.
2.  Locate the following keys on keyboard: Command, Option, P, and R. You will need to hold 
these...

iMac (20-inch, Early/Mid 2009) Troubleshooting — General Troubleshooting 17 2010-11-24
Diagnostic LEDs
The iMac has built-in diagnostic LEDs on the main logic board that can help you to 
troubleshoot the computer. The LEDs are located to the right of the battery (see photo below). 
LED #1 Indicates the trickle voltage from the power supply has been detected by the logic board. 
This LED will remain ON whenever the iMac is connected to a working AC power source. 
The LED will remain on even when the...

iMac (20-inch, Early/Mid 2009) Troubleshooting — General Troubleshooting 18 2010-11-24
Sensor and Fan Connector Locations
Ambient temp sensor and fan connector locations are shown below.  Ensure cables are 
correctly routed and the sensors and fans are properly connected.  If a sensor or fan is faulty or 
not connected, Apple Hardware Test will generate an error code.  

iMac (20-inch, Early/Mid 2009) Troubleshooting — General Troubleshooting 19 2010-11-24
Block Diagram
Refer to this diagram to see how modules are interrelated.   
Note: The iMac (20-inch, Mid 2009) does not have IR or Bluetooth.
MLB
Ambient 
Temperature Sensor
802.11n
Antenna
Bluetooth
Antenna
Display
Temperature Sensor
AC/DCTemperature Sensor
Hard Drive
Temperature Sensor
Optical Drive
 HD Fan
ODD Fan
CPU FanSO-DIMMSO-DIMM
Speaker
Speaker
IR Sensor
Audio Board
Power Button
AC Inlet
CameraMicrophone...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 20 2010-11-24
Symptom Charts
Follow the steps in the order indicated below. If an action resolves the issue, retest the system 
to verify. 
Note: A compilation of Quick Check tables is available at:
http://service.info.apple.com/QRS/en/quickreference.pdf
Startup and Power
No Power, Dead Unit
Unlikely cause:  speakers
Quick Check
SymptomsQuick Check
No Power, Dead Unit
•  No power
•  No fan spin
•  No startup chime
•  No image on external...