Apple imac 20 inch mid 2009 User Manual

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 21 2010-11-24
2. Remove front bezel and locate 
diagnostic LED’s on logic board. 
Plug power cord into system. 
Verify whether diagnostic LED 
#1 turns ON. Yes
Trickle voltage being supplied 
by power supply. Go to step 3.
No Replace power supply.
3.   Press power button while 
monitoring diagnostic LED’s. 
Does diagnostic LED #2 turn 
ON and remain ON after 
pressing the power button? Yes
Power supply functioning and 
logic board detects...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 22 2010-11-24
Won’t Start Up
Quick Check
SymptomsQuick Check
Won’t Start Up
•  No startup chime.
•  Error tones during startup.
•  Grey screen with fan noise, or 
other noise.
•  Will not progress beyond  
Apple logo or spinning gear.
1.  Isolate OS by starting up from original install 
media for the computer, the same make and 
model computer in Target Disk Mode, or 
compatible known-good OS on an external drive. 
Both AirPort and...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 23 2010-11-24
3.  Remove the coin battery on 
the logic board, and leave out 
for approximately 1 minute. 
Then reinstall the battery. This 
will reset the logic board. Does 
the computer startup properly 
now? YesIssue resolved by logic board 
reset. Measure DC voltage 
on the battery touching the 
battery with the red probe, 
and grounding with the black 
probe. If voltage is 2.7v or less, 
replace the battery. See KBase 
article...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 24 2010-11-24
Intermittent Shutdown
Quick Check
SymptomsQuick Check
Intermittent Shutdown
•  Powers off during startup.
•  Powers off during desktop use.
•  Computer restarts 
spontaneously.
•  Powers off when waking from 
sleep.
1.  Isolate OS by starting up from original Install 
media for the computer, the same model 
computer in Target Disk Mode, or compatible 
known-good OS on an external drive. Both 
AirPort and Bluetooth services...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 25 2010-11-24
2. With known-good AC power 
cord and AC outlet, does the 
unit continue to shutdown? Yes
Go to step 3.
No AC power cord/ outlet issue. 
Issue resolved. X03
3.   Disconnect the hard drive 
power cable from the hard 
drive and start the machine 
from the Install DVD, the same 
make and model computer 
in Target Disk Mode, or 
compatible known-good OS 
on an external drive. Does 
the computer continue to 
shutdown? Yes
Go to...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 26 2010-11-24
Kernel Panic, System Crashes
Quick Check
SymptomsQuick Check
Kernel Panic, System Crashes
•  Kernel panic on startup or 
desktop use.
•  System freeze during use.
•  System freeze upon wake from 
sleep.
1.  Isolate OS by starting up system from original 
Install media for the computer, the same make 
and model computer in Target Disk Mode, or 
compatible known-good OS on an external drive. 
Both AirPort and Bluetooth services...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 27 2010-11-24
3.  Use known-good SDRAM in 
the system. Does the computer 
start without kernel panic now? Yes
Install user’s SDRAM and test. 
If kernel panic repeats, replace 
SDRAM. Verify that the correct 
SDRAM is being used. X01
No Go to step 4.
4.  Remove AirPort card and 
test. Does the computer start 
without kernel panic now? Yes
Go to AirPort Card Kernel 
Panic.
No Go to step 5.
5.   Disconnect the hard drive SATA 
cable and...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 28 2010-11-24
No Video
Unlikely cause:  hard drive, optical drive, speakers, camera, microphone
Quick Check
SymptomsQuick Check
No Video
•  No image.
•  Backlight failure.
1.  Check brightness setting.
2.  For no-video issues, connect an external 
display to verify whether iMac video circuitry is 
functioning. If image appears on external display 
go to Backlight Issue/No Backlight.
3.   Reset SMC.
Deep Dive
Check ResultAction Code
1....

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 29 2010-11-24
Corrupted Video
Unlikely cause:  power supply, hard drive, optical drive, fans, speakers, camera, microphone
Quick Check
SymptomsQuick Check
Corrupted Video
•  Text and graphics appear fuzzy
•  Image corrupted 1.
  Set System Preferences/Display LCD panel to 
native resolution. Non-native resolutions are 
unable to produce optimal clarity.
2.  Make sure all relevant software updates have 
been applied. Graphics driver updates...

iMac (20-inch, Early/Mid 2009) Symptom Charts — Startup and Power 30 2010-11-24
3.  Remove logic board, inspect 
connectors for damage or 
corrosion then reinstall. Verify 
whether issue still occurs. Yes
Replace logic board.  
Go to step 4. M04
No Issue likely caused by poor 
connection. Return computer 
to user. M04
4.  Verify whether issue is still 
present with replacement logic 
board installed. Yes
Return to step 1 and retest. X04
No Issue resolved with 
replacement logic board. 
Return computer to...