Apple led cinema display 27inch User Manual

LED Cinema Display (27-inch) Symptom Charts — Startup and Power Issues 21 2010-11-18
Sleep/Wake Issue
Unlikely cause:  LCD panel, fan, camera, speakers, subwoofer, microphone
Quick Check
SymptomsQuick Check
Sleep/Wake Issue
•  Won’t go to sleep or won’t 
wake from sleep 1.
  Verify display is being used with supported 
system with up-to-date system software.
2.  Verify USB/Mini DisplayPort/MagSafe connectors 
are fully seated.
3.   Check brightness setting.
4.  Use with known-good system. If used as...

LED Cinema Display (27-inch) Symptom Charts — Startup and Power Issues 22 2010-11-18
4. Verify if all connections 
between power supply, all-
in-one cable, and logic board 
are secure. See Functional 
Overview. Yes
If connections were secure, 
go to step 5.
No Reseat connectors and retest.
5.   Set digital multimeter to DC 
and correct range, and verify 
that a 11.4 -12.6 V DC voltage is 
present between logic board 
test point (12 V DC) and chassis 
ground (GND). Yes
12 V DC available to logic 
board....

LED Cinema Display (27-inch) Symptom Charts — Display Issues 23 2010-11-18
Display Issues
Blank / No Video, No Backlight
Unlikely cause: fan, camera, speakers, subwoofer, microphone
Quick Check
SymptomsQuick Check
Blank / No Video, No Backlight
•  No video
•  No backlight
•  Dim backlight 1.
  Verify display is used with a supported system 
and up-to-date system software.
2.  Verify USB/Mini DisplayPort/MagSafe connectors 
are fully seated.
3.   Test display with a known-good system.
4.  Connect display...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 24 2010-11-18
3.  Remove glass and LCD panel 
screws, slightly pivot LCD panel 
and verify that the internal 
DisplayPort cable (part of all-in-
one cable) and function cable 
are fully connected to LCD 
panel and logic board. Yes
Go to step 4.
No Reseat DisplayPort connection 
to LCD panel and/or function 
cable connections between 
logic board and LCD panel 
and retest.  
If issue persists go to step 4.  
For any damaged cable, 
replace...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 25 2010-11-18
8. Shine bright (low heat) 
flashlight into the front of the 
LCD. and verify if any image is 
being displayed. Yes
Video is present, so issue is 
only with missing backlight.  
Go to step 9.
No No image displayed on LCD 
Replace LCD panel.  
L03
9.   Remove glass and LCD panel 
screws, lift LCD panel to verify 
that the function cable, and 
LED backlight driver cable 
connections are secure.  
See Functional Overview. Yes
If...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 26 2010-11-18
Noise / Unstable Flicker
Unlikely cause: fan, camera, speakers, subwoofer, microphone
Quick Check
SymptomQuick Check
Noise / Unstable Flicker
•  Image flickers
•  Audible noise
1.  Verify display being used with supported system 
with all software updates installed.
2.  Verify USB/Mini DisplayPort/MagSafe connectors 
are fully seated.
3.   Use with known-good system. If used as second 
display, open System Preferences: Displays...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 27 2010-11-18
2. Verify in the System Profiler’s 
USB device tree that display’s 
USB hub and built-in camera 
are listed continuously and do 
not disappear intermittently 
(refresh System Profiler to 
observe). Yes
Power supply appears OK.  
Go to step 3.
No
Go to Dead Unit/No Power.
3.   Unplug and replug Mini 
DisplayPort and USB 
connectors into a supported 
powered-up portable system 
and monitor the portable’s 
display. Verify that the...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 28 2010-11-18
9.  Reconnect LCD panel and verify 
that video noise/flicker issue is 
appears at all backlight levels. Yes
LED backlight output from 
logic board appears defective.  
Replace logic board.  
 
M25
No Go to step 10.
10.  Reconnect LCD panel and 
verify that video noise/flicker 
issue only appears with low 
backlight levels. Yes
Backlight power from power 
supply appears defective.  
Replace Power supply board.  
 
P04
No Review...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 29 2010-11-18
Deep Dive 
CheckResultAction Code
1.   Connect display to a known-
good supported powered-up 
system with up-to-date system 
software. Check the Automatic 
Brightness Setting checkbox in 
System Preferences: Displays, 
Then cover camera with your 
hand and verify if brightness 
varies accordingly. Yes
Ambient Light Sensor appears 
OK. Go to step 3.
No No or Incorrect brightness 
variation to light change, ALS/
Camera connection...

LED Cinema Display (27-inch) Symptom Charts — Display Issues 30 2010-11-18
5.  Reinstall fan and LCD panel and 
retest. Verify that brightness 
level remains equal while 
display is warming up. YesDisplay brightness does 
not seem to suffer from 
the brightness adjustment 
circuitry. Go to Noise/ 
Unstable Flicker. 
 
No Fan connected and operating. 
but brightness still cannot 
be compensated over 
temperature increase. Replace 
LCD temp sensor cable.  
If issue (brightness still 
getting low after...