Apple imac 20 inch early 2009 User Manual

iMac (20-inch, Early/Mid 2009) Symptom Charts — Input/Output Devices 81 2010-11-24
Deep Dive
CheckResultAction Code
1.   Does the computer recognize 
at all the keyboard or mouse 
when plugged into the rear 
USB ports on the back of the 
iMac? Yes
Test in all USB ports to ensure 
all USB ports working as 
expected. Replace logic board 
for any rear port failures. 
Replace keyboard for any 
keyboard USB port failures. 
Go to step 2.
No
Go to USB Devices Not 
Recognized.
2.  Is keyboard working as...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Input/Output Devices 82 2010-11-24
Uncategorized Symptoms
Quick Check
SymptomsQuick Check
Uncategorized Symptoms
•  Unable to locate appropriate 
symptom code. 1.
  Verify that external I/O device (where applicable) 
works on another system. 
2.  For third party I/O devices make sure necessary 
software is installed and up to date, and that the 
device is supported with the user’s system.
Deep Dive
Check ResultAction Code
1.   Verify whether existing...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Mechanical 83 2010-11-24
Mechanical
Noise/Hum/Vibration
Unlikely cause:  LCD panel, glass panel, enclosure, cables
Quick Check
SymptomsQuick Check
Noise/Hum/Vibration
•  Buzzing noise
•  Rattling noise
•  Ticking noise
•  Squeaking noise
1.  Verify the vents on the bottom and back of the 
computer are free of dust and other obstructions 
that might inhibit proper airflow. 
2.  Launch Applications/Utilities/Activity Monitor. 
Determine whether an application...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Mechanical 84 2010-11-24
Deep Dive
CheckResultAction Code
1.   Run Apple Hardware Test from 
system or Install DVD. Did AHT 
generate any errors? Yes
Go to Apple Hardware Test 
(AHT ) Error Codes table 
to decode error. Follow 
instructions in table for 
resolving error, then retest.
No Go to step 2.
2.  Does noise sound like one or 
more fans running faster than 
expected? Yes
Reset SMC by disconnecting 
power cord for ~15 seconds, 
then retest. If issue...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Mechanical 85 2010-11-24
7.  Reinstall fans while carefully 
ensuring that there are no 
cables routed under or near 
fan assembly that might 
cause interference with the 
fan blades. After reassembling 
system verify that the noise 
issue is resolved. Yes
Noise issue resolved. Suspect 
issue cause by interference 
from wiring or possible 
distortion or fan housing 
when installed in system. 
Proper reassembly resolved 
issue. P04
No Go to step 8.
8....

iMac (20-inch, Early/Mid 2009) Symptom Charts — Mechanical 86 2010-11-24
Fan Failures / Thermal Issues
Unlikely cause:  speakers
Quick Check
SymptomsQuick Check
System Runs Hot
•  System feels very hot
•  Fan(s) not operating
•  Fan(s) running fast
•  System is noisy 1.
  Verify the vents on the bottom and back of the 
system are free of dust and other obstructions 
that might inhibit proper airflow. 
2.  Verify the computer is not exposed to direct 
sunlight which may heat up the enclosure, 
making it...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Mechanical 87 2010-11-24
3.  Remove fans and rotate 
the blades. Verify that fan 
blades spin smoothly without 
interference from fan housing 
and that the fan blades are all 
intact. Yes
Go to step 7.
No Replace affected fan(s). P06
Stand/Hinge Issues
Symptoms Quick Check
Stand/Hinge Issues
•  Bent stand
•  Broken hinge
•  Stripped screw/head
•  Stripped screw boss
1.  Determine whether damage caused by user /
technician environment, accidental damage, or...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Mechanical 88 2010-11-24
Uncategorized Symptoms
CheckResultAction Code
1.   Verify whether existing 
symptom code applies to the 
issue reported by the user. Yes
Jump to appropriate 
symptom code flow.
No
Document reported failure 
and send feedback to 
[email protected] 
stating that a suitable 
symptom code wasn’t found. 
Provide as much detail as 
possible. N99  

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

iMac (20-inch, Early/Mid 2009) Take Apart — General Information 90 2010-11-24
General Information
Opening the Unit
• The iMac (20-inch, Early/Mid 2009) has a glass panel that attaches to the front, which must 
be removed prior to replacing any module on the unit.
•  Important: The glass panel should only be removed by Apple-authorized technicians.  
Follow all cleaning and handling instructions to prevent damaging glass panel or LCD panel.
•  Follow ESD precautions when glass panel is removed.
For more...