Apple Led Cinema Display 24 Service Manual
Apple Technician Guide
LED Cinema Display (24-inch)
Updated: 2010-02-08
Apple Inc.
© 2010 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.
LED Cinema Display (24-inch)
Contents
About This Manual
Updates 7
Updated 8 February 2010 7
Updated 28 October 2009 7
Updated 2 December 2008 7
Feedback 7
Basics
Overview 9
Identifying Features 9
System Requirements 9
Product Congurations 9
Rear View 10
Ports 10
All-In-One Cable 10
Serial Number Location 11
Serial Number on Stand 11
Serial Number on Mechanism 11
Troubleshooting
General Troubleshooting 13
Troubleshooting Theory 13
Hardware vs. Software 13
Functional Overview 14
Block Diagram 15
Test Points Diagram 16
Symptom Charts 17
Startup and Power Issues 17
Dead Unit / No Power 17
Burnt Smell/Odor 19
MagSafe Adapter – No Power 20
Sleep/Wake Issue 21
Uncategorized Symptoms 22
Display Issues 23
Blank / No Video, No Backlight 23
Noise / Unstable Flicker 24
LCD Image Issues 26
Physical Damage 30
Uncategorized Symptoms 30
Input/Output Issues 31
USB Issues 31
Camera Issues 32
Audio Issues 33
Uncategorized Symptoms 36
Mechanical Issues 37
Noise, Hum or Vibration 37
Fan Failures / Thermal Issues 39
Mechanical Physical Damages 40
Uncategorized Symptoms 40
Take Apart
General Information 42
Opening the Unit 42
Required Tools 42
Required Special Tools for Glass Panel 42
Cleaning Tools Starter Kit 43
Cleaning Tool Resources 43
Cleaning & Handling the Glass Panel 43
Do’s and Don’ts 43
Handling a Broken Glass Panel 44
How to Remove a Broken Glass Panel 44
Safety 45
Reassembly Steps 45
Note About Images in This Guide 45
Glass Panel 46
Removal 47
Replacement 48
LCD Panel 51
Removal 52
Replacement 54
Logic Board 55
Removal 56
Replacement 58
Power Supply 59
Blower 61
Removal 62
Replacement 63
Camera 64
Subwoofer 66
AC Inlet 68
All-in-One Cable 70
Speakers 72
Removal 73
Replacement 73
Stand 74
Mechanism 77
Rear Housing 79
Additional Procedures
VESA Mount 81
Retrieving Mechanism 84
Views
Exploded View 89
Cable Routing Diagram 90
Photo of Interior 91
Screw Chart 92
Apple Technician Guide
About This Manual
LED Cinema Display (24-inch)
© 2010 Apple Inc. All rights reserved.
Updates
Updated 8 February 2010
Troubleshooting: General: Test Points Diagram, added TP61•
Troubleshooting: Symptom Charts: “Dead Unit / No Power”:•
Step 5: changed “Yes” Action to lead to Blank/No Video, • Step 3;
Step 8, corrected voltage for TP11 to 24.5VDC (was incorrectly noted as 15VDC); •
Step 9, corrected “TP11” to “TP13”.•
Troubleshooting: Symptom Charts: “Camera Issues”: added link to • kBase #HT3957: “About
the LED Cinema Display iSight Camera Firmware Update 1.0”.
Updated 28 October 2009
Added new section: About This Manual•
Basics: replaced Technical Specications (p. 9) with a link to AppleCare Tech Specs•
Troubleshooting: General: updated Troubleshooting Theory section•
Troubleshooting: Symptom Charts: corrected hyperlink at top of p. 17•
Take Apart: General: replaced ESD section with hyperlinks to current ESD articles & training; •
added section for handling and removing a broken glass panel
Take Apart: Stand: added image showing removal of rear housing from stand; added note •
about VESA Mount procedure
Added new sections: Additional Procedures: VESA Mount and Retrieving Mechanism•
Updated 2 December 2008
Feedback
We want your feedback to help improve this and future Technician Guides!
Please email any comments to: smfeedback6@apple.com
2010-02-08
LED Cinema Display (24-inch) — Updates 7
Apple Technician Guide
Basics
LED Cinema Display (24-inch)
© 2010 Apple Inc. All rights reserved.
Overview
Identifying Features
The LED Cinema Display (24-inch) is an active-matrix LCD with LED backlight that includes a
built-in iSight camera, a 2.1 speaker system, and a microphone. The native resolution is 1920 x
1200 pixels. The all-in-one cable creates a docking station for portable computers, providing a
MagSafe power connection, Mini DisplayPort video connection, and a 3-port USB hub.
The unit has no buttons. Power is controlled by the state of the connected computer. It is
OFF if it detects the DisplayPort source is powered o. It is in Sleep if it detects the DisplayPort
source is powered but does not send a video signal (i.e., Display Sleep). It is ON when the
DisplayPort source sends a valid video signal. Brightness and speaker volume are controlled via
System Preferences in the Mac OS.
System Requirements
The LED Cinema Display (24-inch) works with Mac computers running Mac OS X 10.5 or later
that have a high-performance Mini DisplayPort.
Product Congurations
For product congurations, refer to AppleCare Tech Specs: http://support.apple.com/specs/
2010-02-08
LED Cinema Display (24-inch) Basics — Overview 9
Rear View
The stand is removable in
order to allow the use of a
VESA mount.
Ports
The 3-port USB 2.0 hub
can power three ports at
1.1A each, or up to two
ports at 1.5A each.
All-In-One Cable
Includes (left to right):
USB, Mini DisplayPort, and
MagSafe power.
2010-02-08
LED Cinema Display (24-inch) Basics — Overview 10
Serial Number Location
Serial Number on Stand
The LED Cinema Display (24-inch)’s serial number is located on the base of the stand. When
replacing a stand, transfer the serial number to the new stand.
Serial Number on Mechanism
The LED Cinema Display (24-inch)’s serial number is also located on the hinge mechanism
inside, for users who remove the stand to use a VESA mount. When replacing a mechanism,
transfer the serial number label to the new mechanism.
2010-02-08
LED Cinema Display (24-inch) Basics — Serial Number Location 11
Apple Technician Guide
Troubleshooting
LED Cinema Display (24-inch)
© 2010 Apple Inc. All rights reserved.
General Troubleshooting
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
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
2010-02-08
LED Cinema Display (24-inch) Troubleshooting — General Troubleshooting 13
Functional Overview
LCD Function Interface
• No power to LCD
• No LED backlight
DC In
• No power
Camera
• Not detected in USB Device Tree
• No green camera LED
• No camera video
Fan (1) & LCD (2) Temp Sensors
• Fan runs fast if sensor is:
° disconnected
° connected to wrong location on MLB
° not properly mounted or located
° faulty
Microphone
• Not detected in Sound Pref pane
• No, low, distorted audio input
Subwoofer
• No, low, distorted bass
Right & Left Speakers
• Not detected in Sound Pref pane
• No, low, distorted channel(s)
Blower (Fan)
• No rotation leading to overtemp condition
• Excessive noise/vibration due to faulty fan
* Also see Fan (1) & LCD (2) Temp Sensors
symptoms below.
LED Driver (Backlight)
• No LED backlight
• Dim or low brightness
Upstream USB
• Not detected in USB Device Tree or
System Preference panes
° iSight camera
° Sound output
° Microphone input
° LED calibration &
brightness control
° 3 x USB ports
A guide to possible symptoms as they relate to ports on the main logic board:
2010-02-08
LED Cinema Display (24-inch) Troubleshooting — General Troubleshooting 14
Block Diagram
Refer to this diagram to see how modules are interrelated:
2010-02-08
LED Cinema Display (24-inch) Troubleshooting — General Troubleshooting 15
Test Points Diagram
Below are main logic board test points that you can use
to verify proper power flow in LED Cinema Display (24-inch).
All voltages assume that the display is plugged into
a power outlet, and NOT into the host computer (unless
otherwise noted).
• Turn the dial of your voltmeter/multimeter to measure
DC (direct current) . If your voltmeter requires that
you set a voltage range, choose a DC range that includes
the voltage that you are measuring.
• Connect the black probe to ground by gently inserting into
any of the LCD screw posts closest to the logic board.
Keep in mind that the threading in the screw posts is fragile
and can be easily destroyed.
• Touch the red probe to appropriate test point.
• Verify voltage.
DC In
TP 11: 24.5 VDC
TP 12: 24.5 VDC
TP 13: 12.0 VDC
*TP 14: 5.0 VDC
*only if USB plugged into host
USB Hub 1 for 3 ports
*TP 21: 3.3 VDC
*TP 22: 5.2 VDC
*TP 23: 5.2 VDC
*TP 24: 5.2 VDC
*only if USB plugged into host
USB Hub 2 for camera & audio
*TP 31: 3.3 VDC
*only if USB plugged into host
LED Backlight Driver
TP 81: 24.5 VDC
TP 82: 1.0 VDC
TP 61: 3.3 VDC
Warning:
HIGH VOLTAGE: Use extreme caution
when live testing.
• Never touch the power supply.
• Do NOT lean over or accidentally touch
power supply area during live testing.
• Keep your fingers behind the finger
guards on the test probes when making
measurements on main logic board!
Refer to this diagram to see the location of test points and instructions for their use:
2010-02-08
LED Cinema Display (24-inch) Troubleshooting — General Troubleshooting 16
Symptom Charts
Follow steps in the order indicated below. If an action resolves the issue, retest 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 Issues
Dead Unit / No Power
Unlikely cause: LCD panel, blower, subwoofer, speakers, camera, microphone
Quick Check
Symptoms Quick Check
Dead Unit / No Power
No power•
No image•
No fan spin•
Non-operational•
Verify power source.1.
Verify USB/display/power connectors are fully 2.
seated.
Verify display is used with supported system.3.
Use with known-good system. 4.
If used as second display, check display
preferences to see if display is recognized.
Check brightness setting.5.
Deep Dive
Check Result Action Code
Verify display’s USB hub and 1.
built-in camera are listed in the
System Proler’s USB device
tree.
Yes
No Go to step 2.
Power supply OK. Go to
Blank/No Video symptom
code ow.
2010-02-08
LED Cinema Display (24-inch) Symptom Charts — Startup and Power Issues 17
Unplug and replug the Mini 2.
DisplayPort connector into a
supported system and monitor
the portable’s display. Verify
that the portable’s display
briey turns o then back on.
Yes Logic board OK. Go to
Blank/No Video symptom
code ow.
No Go to step 3.
Remove LCD panel and 3.
disconnect LCD function
interface cable. Verify voltage
on logic board between test
point TP11 (24.5VDC) and
chassis ground (GND) is
23.3–25.7 VDC.
Verify voltage on logic board 4.
between test point TP61
(3.3VDC) and chassis ground
(GND) is 3.1–3.5 VDC.
Verify voltage on logic board 5.
between test point TP13
(12VDC) and chassis ground
(GND) is 11.4–12.6 VDC.
Ve6. rify all connections between
power supply, all-in-one cable,
and logic board are secure. See
Functional Overview.
Yes 24.5VDC from power supply
OK. Go to step 4.
No No power or incorrect power
at logic board.
Go to step 6.
Yes 3.3VDC power on logic board
OK. Go to step 5.
No No power at logic board.
Go to step 9.
Yes All DC voltages present on
logic board; power OK. Go to
Blank/No Video symptom
code ow, Step 3.
No No power at logic board.
Go to step 9.
Yes If connections are secure and
display still does not function
correctly, go to step 8.
No Reseat connectors and retest.
2010-02-08
Disconnect power supply cable 7.
from logic board. Verify cable
voltage at connector between
Pin 1 and chassis ground
(GND) is 14.3–15.8 VDC.
Disconnect all connectors from 8.
the logic board EXCEPT the
power supply cable.
Verify voltage on logic board
between test point TP11
(24.5VDC) and chassis ground
(GND) is 23.3-25.7 VDC.
LED Cinema Display (24-inch) Symptom Charts — Startup and Power Issues 18
Yes Go to step 8.
No
No power or incorrect power
to logic board.
Replace power supply.
Yes Power supply OK. Suspect
possible short, damaged
connector, or faulty sensor/
fan/speaker. Reconnect
connectors one at a time and
retest for 24.5VDC at TP11.
Replace aected part that
causes the 24.5VDC voltage to
disappear.
No
Replace power supply. P01
P01
L14
Disconnect all connectors from 9.
the logic board EXCEPT the
power supply cable.
Verify voltages on logic
board between test points
TP61 (3.3VDC) and chassis
ground (GND) is 3.1–3.5 VDC,
and between TP13 (12VDC)
and chassis ground (GND) is
11.4–12.6 VDC.
Yes Power supply OK. Suspect
possible short, damaged
connector, or faulty sensor/
fan/speaker. Reconnect
connectors one at a time
and retest for 3.3VDC at TP61
and 12VDC at TP13. Replace
aected part that causes the
3.3VDC or 12VDC voltages to
disappear.
L14
No
Replace logic board. L01
Burnt Smell/Odor
Unlikely cause: LCD panel, blower, subwoofer, speakers, camera, microphone
Quick Check
Symptoms Quick Check
Burnt Smell/Odor
No power•
No image•
No fan spin•
Non-operational•
Deep Dive
Verify source of smell/odor is emanating from the 1.
display.
Verify display is functional.2.
Remove air vent obstructions.3.
2010-02-08
Check Result Action Code
Verify by visual inspection of 1.
each module the location the
source of burnt smell/odor
Verify no other modules or 2.
internal cables are aected or
the root cause.
LED Cinema Display (24-inch) Symptom Charts — Startup and Power Issues 19
Yes Located aected module.
Go to step 2.
No
Yes Replace all aected module(s)
No Return unit to user.
Not able to locate aected
module. Go to
Dead Unit / No Power
symptom code ow.
and/or cable(s).
P08
MagSafe Adapter – No Power
Unlikely cause: LCD panel, logic board, blower, subwoofer, speakers, camera, microphone
Quick Check
Symptoms Quick Check
MagSafe Adapter – No Power
No power to MagSafe •
connector
MagSafe connector status LED •
does not illuminate
No power to portable •
computer without battery
Verify power source. 1.
Verify display is operating.2.
Ensure MagSafe connector and receptacle are 3.
clean.
Verify LED glowing amber or green when 4.
MagSafe connector attached to compatible
portable computer.
Deep Dive
Check Result Action Code
Attach MagSafe cable to 1.
known-good compatible
system. Verify connector status
LED illuminates amber or
green.
Visually inspect MagSafe cable 2.
and user’s portable MagSafe
receptacle for physical damage,
stuck pins, debris, or metal
fragments.
Yes LED color illuminates amber
or green depending on
charging state. Go to step 4.
No Go to step 2.
Yes
No Go to step 3.
See kBase #HT2315.
Go to step 4.
2010-02-08
Verify after unplugging and 3.
replugging the display’s AC
power cord, the MagSafe
connector LED color illuminates
amber or green depending
charging state.
Verify a known-good 4.
compatible system operates,
and charges a discharged
battery to 100% simultaneously
from MagSafe cable.
LED Cinema Display (24-inch) Symptom Charts — Startup and Power Issues 20
Yes Go to step 4.
No
Yes Repair complete.
No
Replace all-in-one cable. P15
Replace power supply.
If needed afterwards, refer
to Dead Unit/No Power
symptom code ow.
P01
Sleep/Wake Issue
Unlikely cause: LCD panel, blower, subwoofer, speakers, camera, microphone
Quick Check
Symptoms Quick Check
Sleep/Wake Issue
Won’t go to sleep or wake up •
from sleep
Verify display is being used with supported 1.
system.
Use with known-good system. If used as second 2.
display, check display preferences to see if display
is recognized by system.
Verify USB/display/power connectors are fully 3.
seated.
Check brightness setting.4.
Deep Dive
Check Result Action Code
Verify display’s USB hub and 1.
built-in camera are listed in the
System Proler’s USB device
tree.
Verify voltage on logic 2.
board between J0121 Pin 1
(24.5VDC) and Pin 3 (GND) is
23.3–25.7 VDC.
Yes Power supply OK.
Go to step 3.
No Go to step 2.
Yes Power supply OK.
Go to step 3.
No No power at logic board.
Go to step 4.
2010-02-08
Unplug and replug the Mini 3.
DisplayPort connector into
a supported powered-up
portable system and monitor
the portable’s display. Verify
that the portable’s display
briey turns o then back on.
Verify all connections between 4.
power supply, all-in-one cable,
and logic board are secure. See
Functional Overview.
LED Cinema Display (24-inch) Symptom Charts — Startup and Power Issues 21
Yes Logic board OK.
Go to step 6.
No Go to step 4.
Yes If connections are secure and
display still does not function
correctly, go to step 5.
No Reseat connectors and retest.
Disconnect DC power cable 5.
from J0121 on logic board.
Verify cable voltage at
connector between Pin 1
(24.5VDC) and Pin 3 (GND) is
23.3–25.7 VDC.
Yes Power to logic board.
Replace logic board.
No
No power to logic board.
Replace power supply.
M01
P01
Verify all connections between 6.
logic board and LCD are secure.
Visually inspect cables and
connectors for any debris,
damage, or bent pins.
Yes
No
If connections are secure and
display still does not function
correctly, go to Blank/No
Video symptom code ow.
Reseat connectors and retest.
For damaged AIO cable,
replace all-in-one cable.
Uncategorized Symptoms
Deep Dive
Check Result Action Code
Verify whether existing 1.
symptom code applies to the
issue reported by the user.
Yes Jump to appropriate
symptom code ow.
No
Document reported failure
and send feedback to
smfeedback6@apple.com
stating that a suitable
symptom code wasn’t found.
X04
N99
2010-02-08
LED Cinema Display (24-inch) Symptom Charts — Startup and Power Issues 22
Display Issues
Blank / No Video, No Backlight
Unlikely cause: power supply, blower, subwoofer, speakers, camera, microphone
Quick Check
Symptoms Quick Check
Blank / No Video, No Backlight
No video•
No backlight•
Dim backlight•
Verify display being used with supported system.1.
Verify USB/display/power connectors are fully 2.
seated.
Use with known-good system. If used as second 3.
display, check display preferences to see if display
is recognized by system.
Check brightness setting.4.
Deep Dive
Check Result Action Code
Verify display’s USB hub and 1.
built-in camera are listed in the
System Proler’s USB device
tree.
Unplug and replug the Mini 2.
DisplayPort connector into
a known-good, supported,
powered-up portable system
and monitor the portable’s
display. Verify that the
portable’s display briey turns
o then back on.
Yes Power supply and USB
communication OK.
Go to step 3.
No Go to step 2.
Yes Display detected by system.
Go to step 3.
No
Go to Dead Unit/No Power
symptom code ow.
2010-02-08
Darken room and connect to a 3.
known-good supported system.
Verify backlight by looking for
faint glow from display.
LED Cinema Display (24-inch) Symptom Charts — Display Issues 23
Yes Video signal from host system
OK. Backlight ON.
Go to step 5.
No Go to step 4.
Verify that the LCD function 4.
interface cable and LED driver
cable connections are secure.
See Functional Overview.
Yes If connections are OK and
secure and the display is still
blank, go to step 5.
No
If cable is damaged,
replace all-in-one cable or
replace function cable.
L14
Shine bright (low heat) 5.
ashlight into the front of the
LCD. Verify if an image is being
displayed.
Verify voltage on logic board 6.
between test point TP81
(24.5VDC) and chassis ground
(GND) is 23.3–25.7 VDC.
Yes Image present but backlight
is not ON. Go to step 6.
No
Yes LED backlight power present.
No
Replace LCD panel. L03
Replace LCD panel.
Poor or no LED backlight
power at logic board.
Replace logic board.
Noise / Unstable Flicker
Unlikely cause: blower, subwoofer, speakers, camera, microphone
Quick Check
Symptom Quick Check
Noise / Unstable Flicker
Image icker•
Audible noise•
Verify display being used with supported system.1.
Verify USB/display/power connectors are fully 2.
seated.
L03
L07
2010-02-08
Use with known-good system. If used as second 3.
display, check display preferences to see if display
is recognized by system.
Verify known-good source sound le not causing 4.
speaker distortion.
Deep Dive
Check Result Action Code
Verify if issue is due to video 1.
ickering coming from display.
LED Cinema Display (24-inch) Symptom Charts — Display Issues 24
Yes Suspected ickering issue.
Go to step 2.
No Audible noise issue.
Go to step 8
Verify display’s USB hub and 2.
built-in camera are listed
in the System Proler’s USB
device tree is not disappearing
intermittently (refresh System
Proler to observe).
Yes Power supply OK.
Go to step 3.
No
Go to Dead Unit/No Power
symptom code ow.
Unplug and replug the 3.
Mini DisplayPort and USB
connectors into a supported
powered-up portable system
and monitor the portable’s
display. Verify that the
portable’s display briey turns
o then back on.
Verify all connections between 4.
power supply, all-in-one cable,
LCD, and logic board are secure.
See Functional Overview.
Disconnect all-in-one cable 5.
and LCD function interface
cable from logic board and
system. Verify connectors and
cable under magnication for
pinched cables and damaged/
bent pins.
Disconnect LED driver cable 6.
from logic board. Verify
connectors and cable under
magnication for pinched cable
and damaged or bent pins.
Yes If connections are secure and
display still shows unstable
ickering, go to step 4.
No Reseat connectors and retest.
Yes If connections are secure and
the display is still unstable
ickering, go to step 5.
No Reseat connectors and retest.
Yes
If cable is damaged,
replace all-in-one cable or
replace LCD function
interface cable.
No Go to step 6.
Yes
Damaged LED driver cable.
Replace LCD panel.
No Go to step 7.
L14
L14
2010-02-08
Shine bright (low heat) 7.
ashlight into the front of the
LCD. Verify if an image is being
displayed during ickering.
Verify the source of the noise 8.
is the electrical as opposed to
mechanical
LED Cinema Display (24-inch) Symptom Charts — Display Issues 25
Yes
Image present but backlight
is ickering.
Replace logic board.
No
Replace LCD panel. L06
Yes Noises that are not audible
from the normal user position
are considered acceptable.
No
Noise from another source.
Go to Noise, Hum, Vibration
symptom code ow.
L06
LCD Image Issues
Quick Check
Symptom Quick Check
LCD Issues
Pixel anomalies•
Non-uniform brightness•
Incorrect/missing colors•
Distorted/blurred image•
Vertical/horizontal lines•
Allow display to reach normal operating 1.
temperature for about 15 minutes before
evaluating front-of-screen performance.
Verify display being used with supported 2.
system. If used as second display, check display
preferences to see if display is recognized by
system.
Verify USB/display/power connectors are fully 3.
seated.
Check display preferences for use of custom 4.
display prole.
Check brightness setting.5.
Clean glass panel while checking for dust/debris.6.
Deep Dive: General
Check Result Action Code
Verify if issue is blank/no video.1. Yes
Go to blank/no video.
2010-02-08
Verify if issue is bright or dark 2.
dot pixel anomalies.
Verify if issue is non-uniform 3.
brightness.
Verify if issue is incorrect/4.
missing colors.
Verify if issue is distorted/5.
blurred image.
Verify if issue is vertical or 6.
horizontal lines.
No Go to step 2.
Yes
No Go to step 3.
Yes
No Go to step 4.
Yes
No Go to step 5.
Yes
No Go to step 6.
Yes
No LCD functioning OK.
LED Cinema Display (24-inch) Symptom Charts — Display Issues 26
Go to pixel anomalies.
Go to non-uniform
brightness.
Go to incorrect/missing
colors.
Go to distorted/blurred
image.
Go to vert/horiz lines.
Deep Dive: Pixel Anomalies
Unlikely cause: logic board, power supply, blower, subwoofer, speakers, camera, microphone
Check Result Action Code
Determine if “defects” are dust/1.
debris on surface of glass panel
or LCD panel.
Determine if bright pixel 2.
defects exceed the acceptable
number. See kBase #HT1721
Determine if dark pixel defects 3.
exceed the acceptable
number. See kBase #HT1721
Determine if the combination 4.
of bright/dark pixel defects
exceed the acceptable
number. See kBase #HT1721
Yes
No Go to step 2.
Yes Replace LCD panel. L08
No LCD meets bright pixel defect
Yes Replace LCD panel. L08
No LCD meets dark pixel defect
Yes Replace LCD panel. L08
No Explain to user that LCD is
Deep Dive: Non-Uniform Brightness
Clean glass/LCD panel.
Note: If debris is inside LCD, it
can’t be cleaned, therefore
replace LCD panel.
specications. Go to step 3.
specications. Go to step 3.
within specications for pixel
defects. Do not replace LCD.
Unlikely cause: logic board, power supply, blower, subwoofer, speakers, camera, microphone
Check Result Action Code
Determine if brightness 1.
uniformity issue is visible after
display has warmed up for
approximately 15 minutes.
Display user-provided 2.
examples showing brightness
uniformity issue. Determine if
issue appears excessive when
compared to a similar unit.
Remove front bezel and 3.
loosen screws securing LCD.
Determine if brightness
uniformity improves.
Yes Go to step 2.
No Display backlight can take
several minutes to stabilize.
Yes Go to step 3.
No Explain to user that
LCD appears to meet
specications.
Yes Inspect for mechanical
interference with screws/
chassis/wires making contact
with back of LCD. Retest
No
Replace LCD panel. L07
2010-02-08
LED Cinema Display (24-inch) Symptom Charts — Display Issues 27
Deep Dive: Incorrect/Missing Colors
Unlikely cause: power supply, blower, subwoofer, speakers, camera, microphone
Check Result Action Code
Verify display’s USB hub and 1.
built-in camera are listed in the
System Proler’s USB device
tree.
Verify System Preferences: 2.
Displays: Color is using a valid
display prole for this display.
Verify that the glass panel and 3.
LCD are free of contaminants.
Verify all connections between, 4.
all-in-one cable, LCD, and
logic board are secure. See
Functional Overview.
Yes Power supply and USB
communication OK.
Go to step 2.
No
Yes If display prole is valid and
No Calibrate display by creating a
Yes Go to step 4.
No
Yes Go to step 5.
No Reseat connections, replace
Go to USB Issues symptom
code ow.
the colors are still incorrect or
missing, go to step 3.
manual prole using calibrate
feature in System Preferences:
Displays: Color. Retest.
Clean glass/LCD panel.
Retest.
damaged cable(s) as needed.
Retest.
2010-02-08
Set desktop pattern in System 5.
Preferences to “solid gray light.”
Verify if incorrect/missing color
issue aects entire display.
Set up user’s display side-by-6.
side with a known-good display
showing the same image. Verify
if issue is noticeably worse on
the display being tested.
LED Cinema Display (24-inch) Symptom Charts — Display Issues 28
Yes
No Go to step 6.
Yes
No Small variations in color
Suspect poor video
connection.
Replace all-in-one cable.
Replace LCD panel. L02
uniformity are normal and do
not warrant replacement or
repair of the display.
L14
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