Apple iMac 27 late 2009 Service Manual
Apple Technician Guide
iMac (27-inch, Late 2009)
2009-12-15
Apple Inc.
© 2009 Apple Inc. All rights reserved.
Under the copyright laws, this document may not be copied, in whole or in part, without the
written consent of Apple.
Every eort has been made to ensure that the information in this document is accurate. Apple
is not responsible for printing or clerical errors.
Apple
1 Innite Loop
Cupertino, CA 95014-2084
USA
+ 1 408 996 1010
www.apple.com
Apple, the Apple logo, Mac, and Macintosh are trademarks of Apple Inc., registered in the U.S.
and other countries.
iMac (27-inch, Late 2009)
Contents
About This Guide
Updates 10
15 December 2009 10
20 November 2009 10
11 November 2009 10
28 October 2009 11
27 October 2009 11
Apple Technician Guide introduced 20 October 2009 11
Feedback 11
Basics
Overview 13
Identifying Features 14
Product Congurations 14
Wireless Troubleshooting 14
Safety Precautions 15
Serial Number Location 16
Troubleshooting
General Troubleshooting 18
Wireless Troubleshooting 18
Update System Software & Firmware 18
Troubleshooting Theory 18
Hardware vs. Software 19
Power On Self Test (POST) 19
Resetting the System Management Controller (SMC) 19
Resetting Parameter RAM (PRAM) 20
Starting Up in Safe Mode 20
Diagnostics 21
Diagnostic LEDs 23
Location of Diagnostic LEDs 24
LED Startup Sequence 26
Logic Board Test Points 27
Sensor and Fan Connector Locations 28
Block Diagram 29
Symptom Charts 30
Startup and Power 30
No Power, Dead Unit 30
Won’t Start Up 32
Intermittent Shutdown 34
Kernel Panic, System Crashes 36
No Video 38
Corrupted Video 40
Burnt Smell/Odor 43
Uncategorized Symptoms 44
Display 45
Backlight Issue/No Backlight 45
Noise / Unstable Flickering 47
LCD Image Issues 49
Incorrect/Missing Colors 50
Distorted/Blurred Image 51
Pixel Anomalies 53
Vertical/Horizontal Lines 54
Non-Uniform Brightness 56
Cosmetic Defects 57
Uncategorized Symptoms 57
Mass Storage 58
Hard Drive Not Recognized 58
Hard Drive Noisy 61
Optical Drive Not Recognized 63
Optical Drive Won’t Accept/Eject Media 64
Optical Drive Read/Write Error 65
Optical Drive Not Performing to Specications 67
Optical Drive Noisy 68
SD Card Will Not Insert Into Slot 69
SD Card Not Recognized 70
Uncategorized Symptoms 71
Communications 72
AirPort/Bluetooth Issues 72
AirPort Card Kernel Panic 74
Ethernet Port/Device Issue 75
Wireless Input Device Doesn’t Pair 76
Wireless Input Device Loses Connection 78
Input/Output Devices 81
Apple Remote Inoperable 81
Audio: Microphone 83
Audio: Built-in Speakers Have Distorted Sound 84
Audio: Built-in Speakers Have No Audio 85
Camera Issues 87
FireWire Device Not Recognized 88
USB Device Not Recognized 90
Wired Keyboard Does Not Function Properly 92
Keyboard: Specic Keys Do Not Respond 94
Wired Keyboard/Mouse Not Recognized 94
Uncategorized Symptoms 96
Mechanical 97
Noise/Hum/Vibration 97
Fan Failures / Thermal Issues 100
Stand/Hinge Issues 101
Physical Damage 102
Uncategorized Symptoms 102
Take Apart
General Information 104
Opening the Unit 104
Required Tools 104
Cleaning & Handling the Glass Panel 106
Do’s and Don’ts 106
Handling a Broken Glass Panel 107
Safety 112
Logic Board Handling 113
Reassembly Steps 113
Note About Images in This Manual 113
Screw Sizes 113
Access Door 114
Memory 116
Removal 117
Reassembly 117
Glass Panel 118
Removal 119
Reassembly 120
Camera 123
LCD Panel 125
Removal 126
Reassembly 129
Vertical Sync Cable 131
LCD Temp Sensor Cable 132
DisplayPort Cable 133
Audio Ports and Cable 134
Bluetooth Antenna 136
AirPort Antenna 138
Bluetooth Board 140
AirPort Card 142
AirPort Cable 144
AirPort Carrier Board 146
LED Backlight Board 148
Power Supply 150
Removal 151
Reassembly 152
Backlight Pressure Wall 153
Power Supply/Hard drive Pressure Wall 155
Removal 156
Reassembly 15 6
Hard Drive 158
Removal 159
Reassembly 160
Hard Drive Sensor Cable 161
Removal 162
Reassembly 162
Optical Drive 163
Removal 164
Reassembly 166
Optical Sensor Cable 168
Optical Drive Fan 170
SD Board 172
SD Card Cable 174
IR Board 176
Removal 177
Logic Board 178
Removal 179
Reassembly 183
Video Card 187
Hard Drive Data Cable 190
Removal 191
Optical Drive Data Cable 193
Removal 194
Battery 195
Removal 196
Reassembly 196
Optical Pressure Wall 197
Right Speaker 199
CPU Fan 201
Removal 202
Reassembly 203
Ambient Temp Sensor 204
Removal 205
Reassembly 205
Left Speaker 206
Removal 207
Reassembly 207
Hard Drive Fan 209
Mechanism Cover 211
Mechanism 213
Bluetooth Cable 215
Cable, AC/DC Power/Backlight/SATA 217
Camera Cable 219
Microphone Cable 222
Rear Housing 223
Stand 224
Removal 225
Reassembly 226
Additional Procedures
Retrieving Mechanism 229
Views
Exploded Views 234
Exploded View #1 234
Exploded View #2 235
Exploded View #3 236
External Views 237
Rear View 237
Ports 238
Internal Views 239
Components Below LCD 239
Inside Rear Housing 239
Logic Board, Top Side 240
Logic Board, Bottom Side 240
Screw Chart 241
Apple Technician Guide
About This Guide
iMac (27-inch, Late 2009)
© 2009 Apple Inc. All rights reserved.
Updates
15 December 2009
Troubleshooting:
General Troubleshooting: Updated Apple Service Diagnostic and Apple Hardware Test •
version numbers, updated Apple Hardware Test error code table.
Startup Power and Display chapters: Updated Flickering/No Video/ Backlight Issue/•
Corrupted Video topics to alert technicians to check:
Mac OS X version installed is the build version supported on the hardware. See • kBase
#TS3101: Mac (Late 2009): Using the correct Mac OS X system software.
Cable connections • on back of LCD panel; check for signs of damage, corrosion,
or pinched wires. Reseat/replace DisplayPort cable and Vertical sync cable when
instructed.
20 November 2009
Troubleshooting:•
Mechanical: Fan noise issues: updated two topics, “Noise/Hum/Vibration” and “Fan •
Failures/Thermal Issues” with the following information:
Check: Verify if any tape, gasket, cable label, or cable is touching the fan blades and •
causing a ticking noise.
Actions: Secure the material so it doesn’t touch fan blades. If tape adhesive has lost its •
stickiness, replace that section of tape.
11 November 2009
Take Apart:
General Information: Added graphics to topic, “How to Remove a Broken Glass Panel.”•
Hard drive: Added information on the Western Digital drive and sensor cable. Orient the •
drive with its circuit board facing up and connect the sensor cable to the hard drive pins,
leaving the 2 left pins unconnected (exposed).
Views, Exploded Views:
Added AirPort (922-9286) and Bluetooth(922-9285) antennas•
Added parts unique to the iMac (27-inch, Quad Core, Late 2009) •
Skin temp sensor 922-9287•
SDRAM DIMMs, 661-5453 and 661-5454•
Power supply, 661-5468•
Logic boards, 661-5428 and 661-5429•
Optical drive,• 922-5284
2009-12-16
iMac (27-inch, Late 2009) About This Guide — Updates 10
28 October 2009
Take Apart: Added backlight cable to list of items included with replacement panel
27 October 2009
Formatting changes throughout manual•
Troubleshooting: added new LED Location graphic on page 22 •
Apple Technician Guide introduced 20 October 2009
Feedback
We want your feedback to help improve this and future Technician Guides! Please email any comments to smfeedback2@
apple.com
2009-12-16
iMac (27-inch, Late 2009) About This Guide — Feedback 11
Apple Technician Guide
Basics
iMac (27-inch, Late 2009)
© 2009 Apple Inc. All rights reserved.
Overview
2009-12-16
Introducing the iMac (27-inch, Late 2009) with a new edge-to-edge glass design and seamless
all aluminum enclosure. The new iMac line is the fastest ever with Intel Core 2 Duo processors
starting at 3.06 GHz, and Core i5 and i7 quad-core processors for up to twice the performance.
iMac (27-inch, Late 2009) Basics — Overview 13
Identifying Features
The iMac (27-inch, Late 2009) computer features include:
LED-backlit 27-inch display•
Increased processor speeds: •
3.06GHz and 3.33GHz Intel Core 2 Duo•
2.66GHz quad-core Intel Core i5 •
2.8GHz quad-core Intel Core i7•
Four RAM slots, each of which can accept a 2 GB or 4 GB SO-DIMM up to 16GB•
SD card reader slot•
Mini DisplayPort output (DVI, VGA, and dual-link DVI) and supports input from external •
DisplayPort sources (adapters sold separately)
Graphics and video support: •
ATI Radeon HD 4670 graphics processor with 256MB of GDDR3 memory (dual-core)•
ATI Radeon HD 4850 graphics processor with 512MB of GDDR3 memory (dual-core)•
ATI Radeon HD 4850 graphics processor with 512MB of GDDR3 memory (quad-core)•
Hard drive: 1TB, 2TB (CTO only) •
New Apple Magic Mouse and Apple Wireless Keyboard (2009), standard with all •
congurations
Ships with and requires at least Mac OS 10.6.1 (Snow Leopard)•
Product Congurations
For product congurations, refer to Apple Support Tech Specs: http://support.apple.com/
specs/
Wireless Troubleshooting
If you’re having issues with Bluetooth and wireless connectivity issues, refer to the following
Knowledge Base articles:
Desktop computers: Troubleshooting wireless mouse and keyboard issues • http://support.
apple.com/kb/TS3048
AirPort and Bluetooth: Potential sources of interference • http://support.apple.com/kb/
HT1365
Apple Wireless Keyboard and Mouse: How to install batteries • http://support.apple.com/
kb/HT3903
2009-12-16
iMac (27-inch, Late 2009) Basics — Overview 14
Safety Precautions
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.
WARNING: If the computer is shut down by removing 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.
2009-12-16
iMac (27-inch, Late 2009) Basics — Overview 15
Serial Number Location
The iMac (27-inch, Late 2009) serial number is located on the base of the stand. When
replacing a stand, transfer the serial number to the new stand.
2009-12-16
iMac (27-inch, Late 2009) Basics — Overview 16
Apple Technician Guide
Troubleshooting
iMac (27-inch, Late 2009)
© 2009 Apple Inc. All rights reserved.
General Troubleshooting
Wireless Troubleshooting
If you’re having issues with Bluetooth and wireless connectivity issues, refer to the following
Knowledge Base articles:
Desktop computers: Troubleshooting wireless mouse and keyboard issues • http://support.
apple.com/kb/TS3048
AirPort and Bluetooth: Potential sources of interference • http://support.apple.com/kb/
HT1365
Apple Wireless Keyboard and Mouse: How to install batteries • http://support.apple.com/kb/
HT3903
Update System Software & Firmware
Important: Ensure the correct version Mac OS X and latest software and rmware updates have
been applied before you begin troubleshooting. Computers sometimes exhibit symptoms that
indicate the wrong Mac OS X system software is installed. Refer to the following article about
using the correct Mac OS X ystem software:
kBase # TS3101: iMac (Late 2009): Using the correct Mac OS X system software
Firmware is the name given to software that is written into memory circuits such as ash
memory, that will hold the software code indenitely, even when power is removed from
the hardware. Firmware on Intel Mac computers is designed to be updated if necessary by
running the Mac OS X Software Update check (available in the Apple menu) while computer is
connected to the Internet. For more information about rmware updates, refer to:
kBase # HT1557: About rmware updates for Intel-based Macs
Troubleshooting Theory
For general information on troubleshooting theory, go to GSX and nd the Service Training
course menu link. From there you can access the Troubleshooting Theory self-paced course.
Hardware vs. Software
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 18
Hardware vs. Software
For information on how to isolate a hardware issue from a software issue, refer to:
kBase #TS1388: Isolating issues in Mac OS X
For information on how to troubleshoot a software issue, refer to:
kBase #HT1199: Mac OS X: How to troubleshoot a software issue
kBase #TS1394: Mac OS X: Troubleshooting installation and software updates
kBase #HT2956: Troubleshooting Mac OS X installation from CD or DVD
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-specication or no SDRAM, or if the RAM installed does not •
meet the appropriate specications, the screen will remain black but the computer will
beep This error condition may be due to physically damaged RAM, installing the incorrect
type of RAM, or not having RAM installed.
Some RAM may appear to pass the Power-On-Self-Test (POST) but still cannot be used by •
the operating system. In this case, the computer will display a gray screen, sound three
tones and repeat the tones until the computer is turned o.
The solution to both of these situations is to rst re-seat the memory and test the computer •
again. If the memory fails the POST test again, remove all installed memory and test by
installing one by one each memory that has been veried to work correctly on another
system (i.e., “known-good”) or order new memory.
Resetting the System Management Controller (SMC)
The System Management Controller (SMC) is a chip on logic board that controls all power
functions. If computer is experiencing any power issue, such as not starting up, not displaying
video, sleep issues, or fan noise issues, resetting SMC may resolve it. To reset SMC on an iMac:
From Apple menu, choose Shut Down (or if the computer is not responding, hold power 1.
button for approximately ten seconds until it powers o).
Unplug all cables from computer, including power cord.2.
Wait at least 15 seconds. SMC reset occurs automatically once iMac has been unplugged 3.
from AC power source for several seconds.
Plug power cord back in, making sure power button is not being pressed.4.
Press power button on back to start up computer.5.
For more information, refer to:
kBase #HT1543: Intel-based iMac: How to reset the System Management Controller
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 19
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:
Shut down the computer.1.
Locate the following keys on keyboard: Command, Option, P, and R. You will need to hold 2.
these keys down simultaneously in Step 4.
Note: If the keyboard does not have an Option key, use the Alt key instead.
Press power button.3.
Immediately press and hold Command-Option-P-R keys. 4.
Important: You must press this key combination before the gray screen appears.
Hold down keys until the computer restarts, and you hear the startup chime a second time.5.
Release keys.6.
For more information, refer to:
kBase #HT1242: Mac OS X: What’s stored in PRAM
kBase #HT1379: Resetting your Mac’s PRAM and NVRAM
Starting Up in Safe Mode
A Safe Boot is a special way to start Mac OS X when troubleshooting. To start up in Safe Mode:
Make sure computer is shut down.1.
Press power button.2.
Immediately after you hear the startup tone, press and hold Shift key. 3.
Note: The Shift key should be held as soon as possible after startup tone but not before.
Release Shift key when you see the screen with the gray Apple and progress indicator (looks 4.
like a spinning gear). During startup, ”Safe Boot” appears on the Mac OS X startup screen.
To leave Safe Mode, restart computer normally, without holding down any keys during startup.5.
For more information, refer to:
kBase #HT1564: Mac OS X: What is Safe Boot, Safe Mode?
kBase #TS1884: Safe Boot takes longer than normal startup
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 20
Diagnostics
Run Apple Service Diagnostic version 3S135 to determine if any thermal sensors or blowers are malfunctioning. If
ASD is not available, run Apple Hardware Test version 3A188 by holding down the D key during startup. When a test
reports an error, reseat appropriate connections. If issue persists, replace the corresponding part (sensor, blower, logic
board, video card, or power supply). See Apple Hardware Error code chart below for correlation between error code,
aected sensor, sensor location, and additional checks to perform.
AHT Error code Suspected part and
Location
4SNS/1/C0000008:TA0P - xxx Ambient temp sensor
damaged or disconnected
from logic board.
4SNS/1/C0000008 T00p-xxx ODD temp sensor
damaged or disconnected
from logic board.
4SNS/1/C0000008 TH00--xxx HDD temp sensor
damaged or disconnected
from logic board. Use the
correct sensor cable, each
drive vendor has a unique
sensor cable.
Suggested Action Notes
Verify sensor cable is
securely connected to the
top edge of the logic board
and attached to the left
speaker housig. Replace
sensor cable if damaged.
Verify sensor cable is
securely connected to the
logic board and the sensor
is properly attached to the
ODD mechanism. Replace
sensor cable if damaged.
Verify sensor cable is
securely connected to top
left side of logic board and
it’s connected to hard drive.
Check for damaged cable
on logic board.
All fans ramp at full
speed if sensor is
disconnected.
The ODD fan will run
at full speed if sensor is
disconnected.
The HD fan may run at
full speed if the sensor
is disconnected.
2009-12-16
4SNS/1/C0000008 TL0p LCD temp sensor on LCD
is damaged or
disconnected from top of
logic board
4SNS/1/C0000008 TS2P-xxx Skin temp sensor (Quad-
core models only) is
damaged or disconnected
from top of logic board.
Verify that the LCD sensor
cable is securely connected
to the logic board and the
sensor is attached to the
LCD. Replace the sensor
cable if damaged
Verify that the skin temp
sensor cable is securely
connected to the top
of the logic board and
sensor is attached to rear
housing (near the camera).
Replace the sensor cable if
damaged.
iMac (27-inch, Late 2009) — General Troubleshooting 21
The CPU fan will run at
full speed if the sensor
is disconnected.
AHT Error code Suspected part and
Location
Suggested Action Notes
4SNS/1/40000000 TC0H CPU temp sensor located
on back side of logic
board; this sensor is not
available as a service part
4SNS/1/40000000:TG0H GPU temp sensor is
disconnected or faulty
(located on back side of
logic board)
Check CPU sensor cable
connection to logic board.
It requires removal of the
logic board.
Check GPU sensor cable
connection to logic board.
It requires removal of the
logic board.
4MOT/4/40000002 :ODD-xxx Optical fan/blower Verify that the ODD
blower/fan cable is securely
connected to the right side
of the logic board and that
there are no obstructions
that would prevent the
blower/fan from rotating.
Replace fan if the error
continues.
4MOT/4/40000002 :HDD-xxx Hard drive fan/blower,
located below logic board,
near hard drive
Verify that the HDD
blower/fan cable is securely
connected to the top of the
logic board and that there
are no obstructions that
would prevent the blower/
fan from rotating. Replace
fan if the error continues.
4MOT/4/40000002 :CPU-xxx CPU fan/blower, located
next to left speaker (logic
board has to be removed
to replace CPU blower)
Verify that the CPUblower/
fan cable is securely
connected to the left side
of the logic board and that
there are no obstructions
that would prevent the
blower/fan from rotating.
Replace fan if the error
continues.
If the sensor is
disconnected, the
CPU fan will run at full
speed.
If sensor is
disconnected the CPU
fan will run at full
speed.
Normal fan operation,
except the ODD blower
Normal fan operation,
except the HDD blower
Normal fan operation,
except the CPU blower
Note: Make sure black
mylar tape along the
bottom of LCD panel
is not obstructing fan
blades, if so, cut tape
and re-stick to LCD.
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 22
Diagnostic LEDs
The iMac (27-inch, Late 2009) computer has four built-in diagnostic LEDs on the main logic
board that can help you to troubleshoot the computer. The LEDs are located on the bottom left
edge of the logic board (under a piece of black mylar tape) and can only be seen when looking
through the lower vents of the enclosure. Refer to the next page for a close up graphic of the
troubleshooting LEDs.
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 23
Location of Diagnostic LEDs
The LEDs are located under the mylar tape, on the bottom, left corner of the logic board. They
can only be seen when looking through lower vents of rear housing.
LED Functions
2009-12-16
LED #1
Indicates that the trickle voltage from the power supply has been detected by the main •
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 computer has been shut down or
put to sleep. The LED will turn o only if the AC power source is disconnected or the power
supply is faulty.
iMac (27-inch, Late 2009) — General Troubleshooting 24
LED #2
Indicates that the main logic board has detected proper power from the power supply •
when the computer is turned on and that logic board voltage regulators are functioning
properly. This LED will be ON when the computer is turned on and the power supply is
working correctly.
LED #3
Indicates that the computer and the video card are communicating. This LED will be ON •
when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON
and you heard the startup sound, but LED 3 is OFF, then the video card might be installed
incorrectly or need replacement.
LED #4
Indicates that the computer and the LCD panel are communicating. This LED will be ON •
when the computer is turned on and video signal is being generated. If the LED is ON and
there is no image on the display, then the LCD panel, the LED backlight board, or the cables
between might be installed incorrectly or need replacement.
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 25
LED Startup Sequence
LED #1 = Power available.
If no LED is visible:
Verify AC source •
Verify known-good AC cable is connected•
Verify cable connection between AC inlet and power supply•
Verify cable connection between power supply and logic board•
Verify power supply•
LED #1 + LED #2 = Power available, and system is powered on.
If second LED is not visible when power button is pressed:
Verify power button connection to logic board•
Verify power button functionality•
Verify cable connection between power supply and logic board•
Verify power supply•
Verify logic board•
LED #1 + LED #2 + LED #3 = Power available, system is powered on, and video card found.
If third LED is not visible after power on:
Verify that the MXM video card is seated properly•
Verify logic board•
LED #1 + LED #2 + LED #3 + LED #4 = Power available, system is powered on, video card
found, and internal LCD found.
If fourth LED is not visible after power on:
Verify cable connections between LCD panel and logic board•
Inspect LCD display cables for cable damage •
Verify external video functionality, and according to result check the following items:•
-If external display works then verify/replace the LED backlight board
-If external display works then verify/replace the LCD panel
-If external display does not work verify/replace the logic board
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 26
Logic Board Test Points
Some test points are accessible on the logic board when the LCD panel is removed. The test
points are dened below.
Logic Board Test Point Function
Pin 1 Ground
Pin 4 Standby 12V power (permanent power coming from power supply
and present as long as AC cable is connected, even if computer is
o); corresponds to LED #1
Pin 6 Backlight Control pulse width modulated signal (from logic board
to LED backlight board, to adjust the backlight level setting
according to user setup)
Pin 11 12V Run-Mode power to logic board (coming from power supply,
present as long as system is on or asleep); corresponds to LED #2
Pin12 Power On Request signal (from logic board to power supply when
power button is pressed)
Pin 13 Backlight Enable (signal from logic board to Backlight Controller
board, to enable backlight
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 27
Sensor and Fan Connector Locations
Ambient temp sensors and fans connectors 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 and Apple Service Diagnostic will generate an error code.
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 28
Block Diagram
SO-DIMM
Antenna
Antenna
Antenna
SO-DIMM
Temperature
Sensor
Temperature
Sensor
Fan
MLB
SO-DIMM
Display
AC/DC
Power
Button
Bluetooth
Speakers
Hard Drive
Optical Drive
AC Inlet
Temp
Sensor
Camera
Microphone
Speakers
Backlight
Controller
Fan
Fan
MXM
802.11n
Ambient
Temperature
Sensor
K22/K23 System Block Diagram
09/01/2009
David Cox
Apple Confidential
IR Sensor
SD Card
Reader
SO-DIMM
Refer to this diagram to see how modules are interrelated.
2009-12-16
iMac (27-inch, Late 2009) — General Troubleshooting 29
Symptom Charts
Follow steps in the order indicated below. If an action resolves the issue, retest system to verify.
Startup and Power
No Power, Dead Unit
Unlikely cause: speakers
Quick Check
Symptoms Quick Check
No Power, Dead Unit
No power•
No fan spin•
No startup chime•
No image on external display•
No hard drive or optical drive •
activity
Caps Lock LED on wired •
keyboard doesn’t light when
pressed.
Verify power source.1.
Verify power cable.2.
Listen closely for signs of activity from system 3.
including: rotating fans, hard drive or optical drive
activity, startup chime, etc.
Deep Dive
Check Result Action Code
Power ON system. Verify if 1.
there is any indication that the
system has powered up (fan
rotation, hard drive or optical
drive noise, backlight turns on).
Locate diagnostic LEDs in 2.
bottom case vents. Plug AC
cord into system. Verify if
diagnostic LED #1 turns ON.
You may alternately check for
presence of a 12V DC signal
between pin 4 and pin 1 of
logic board.
Yes The symptom is powering
up. Go to Won’t Start Up
symptom ow.
No Go to step 2.
Yes Standby power voltage being
supplied by power supply.
Go to step 3.
No Replace power supply.
2009-12-16
iMac (27-inch, Late 2009) Symptom Charts — Startup and Power 30
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