Apple cinema display 22 lcd User Manual

							Apple Cinema Display 22 (ADC) Troubleshooting - 1
 Symptom Charts
Symptom Charts
How to Use the Symptom Charts
The Symptom Charts included in this chapter will help you diagnose specific symptoms 
related to the product. Because cures are listed on the charts in the order of most likely 
solution, try the cures in the order presented. Verify whether or not the product continues 
to exhibit the symptom. If the symptom persists, try the next cure. 
Note:  If you have replaced a module, reinstall the original module before you proceed to 
the next cure.
Note:  Referring to the Block Diagram in this manual may be helpful.
Blank screen
This symptom may indicate a problem with the LCD panel, backlight bulbs, inverter, main 
board, or related cables or connectors.
1. Check ADC cable. Replace cable if damaged.
2. Check for bent pins in the ADC connector (note, it is normal for two of the pins to be 
slightly longer than the others). If pins are slightly bent, carefully straighten. If pins are 
severely bent, replace cable. Also, inspect or have the customer inspect the display 
port on the computer for broken pin dividers. If the display port is damaged it must be 
repaired before inserting the ADC connector.
3. Plug the display into a known-good computer with a known-good video card and ADC 
display port. Boot the computer and allow enough time to finish booting.
4. If the power button on the display is flashing, two short flashes then a long flash, in a 
delayed repeating pattern, this indicates trouble with either the inverter, backlight 
bulbs or related cables or connectors. With this in mind, continue with the 
troubleshooting steps to determine the problem. 
						

							2 - Apple Cinema Display 22 (ADC) Troubleshooting
 Symptom Charts 5. To check whether the LCD is working, make sure that the display’s power light is on 
(glows white). Shine a bright light such as sunlight or a high intensity lamp (see 
Important note, below) into the screen and at the same time notice whether you can 
see faint images of desktop items on the screen. 
• If desktop items can be seen, the LCD panel is working. The problem may be with 
the inverter or backlight bulbs or related cables or connectors. Continue with the 
troubleshooting steps.
• If no desktop items can be seen, the problem may be with the LCD panel or the 
main board or related cables or connectors.
Important: Lights get very hot and can quickly damage the display; be extremely 
careful not to allow too much heat next to the screen or other parts of the display and 
do not allow the light fixture to touch the screen, or damage can result.
6. Warning: The inverter board generates high voltage when the display is plugged 
in. Do not touch the inverter board components, pins or connectors, when the 
display is connected to the computer.
Disconnect the display from the computer, then open the display and check for 
secure connections at J2, J5, J6, J4, J3 and the ADC cable connection to the panel.
Note: Refer to the Block Diagram in this manual for connector locations.
7. Plug the display into a known-good computer, then boot the computer.
8. Verify +24-28V at pin 1 of J4. If not, replace ADC cable.
9. Verify +15V at pin 1 of J2. If not, replace the main board.
10. Verify +5V at pin 1 of J5. If not, replace the main board. 
						

							Apple Cinema Display 22 (ADC) Troubleshooting - 3
 Symptom Charts
Partially dim screen
This symptom indicates a problem with the inverter or backlight bulbs (on the side of the 
display that is dim), or related cables or connectors. This may be caused by the backlight 
bulbs or the inverter not working properly.
1. Plug the display into a known-good computer with a known-good video card and ADC 
display port. Boot the computer.
2. Notice whether the power button on the display is flashing, two short flashes then a 
long flash, in a delayed repeating pattern. This indicates trouble with either the 
inverter, backlight bulbs or related cables or connectors (this indicator may not always 
be exhibited). With this in mind, continue with the troubleshooting steps to determine 
the problem.
3. Warning: The inverter board generates high voltage when the display is plugged 
in. Do not touch the inverter board components, pins or connectors, when the 
display is connected to the computer.
Disconnect the display from the computer, then open the display and check for 
secure connections where the backlight bulbs plug into the inverter.
Note: Refer to the Block Diagram in this manual for connector locations.
4.Important: The backlight bulbs are extremely delicate. Handle with care.
To determine whether the problem is with the backlight bulbs or the inverter board, 
disconnect the two CN connectors to the backlight bulbs on the side that is dim. 
Connect the CN connectors to a known good backlight bulb tray (the bulb tray from 
the other side of the display can be removed and plugged in to test, if known good). 
Connect the display’s ADC connector to a known-good computer, then boot the 
computer. If one or more of the bulbs does not light, replace the inverter. If the bulbs 
light correctly, the original backlight bulb tray is bad, replace the bulb tray.
Note: The top and bottom backlight bulb trays are interchangeable. The bulb trays 
are not specific to the top or bottom. 
						

							4 - Apple Cinema Display 22 (ADC) Troubleshooting
 Symptom Charts
USB device not working
1. Check for bent pins in the ADC connector (note, it is normal for two of the pins to be 
slightly longer than the others). If pins are slightly bent, carefully straighten. If pins are 
severely bent, replace cable. Also, inspect or have the customer inspect the display 
port on the computer for broken pin dividers. If the display port is damaged it must be 
repaired before inserting the ADC connector.
2. Plug the display into a computer with a known-good ADC display port, then boot the 
computer. On the back of the display, connect a known-good USB device into one of 
the USB ports, then check Apple System Profiler to see if it is recognized. Check both 
USB ports.
Note: 
x+R, refreshes the Apple System Profiler list when USB devices are changed.
• If the device is recognized, the customer’s USB device may be the issue.
• If not, check the J1 USB connections and cables. If not that, replace the main 
board.
Power/brightness switch not working
1. Check J5 connection and verify that the cable is connected to the power/brightness 
switch cable connector.
2. Replace the rear cover (includes power/brightness switch board).
Note: The power/brightness switch board is permanently attached to the rear cover.
3. Replace main board. 
						

							Apple Cinema Display 22 (ADC) Troubleshooting - 5
 Symptom Charts
When displaying a single color over the screen area, the LCD panel shows one 
or more pixels that are not properly lit
Active-matrix LCD technology uses rows and columns of addressable locations (pixels) 
that render text and images on screen. Each pixel location has three separate subpixels 
(red, green, and blue) that allow the image to be rendered in full color. Each subpixel has a 
corresponding transistor responsible for turning the subpixel on or off.
There are typically millions of these subpixels on an LCD display. For example, the LCD 
panel used in the Apple Cinema HD display is made up of 2.3 million pixels and 6.9 million 
red, green, and blue subpixels. Occasionally, a transistor does not work perfectly, which 
may result in the affected subpixel being turned on (bright) or turned off (dark). With the 
millions of subpixels on a display, it is quite possible to have a low number of faulty 
transistors on an LCD. Therefore, a certain number of subpixel anomalies is considered 
acceptable. Rejecting all but perfect LCD panels would significantly increase the retail 
price for products using LCD displays. These factors apply to all manufacturers using LCD 
technology—not just Apple products.
To determine whether or not the display has an acceptable number of pixel anomalies, 
follow the steps below:
1. Set the display image to one of the following colors: all-white display, all-red display, 
all-green display, or all-blue display. 
Note: Knowledge Base article 112125: Service Diagnostics Matrix, has the LCD 
Tester Diagnostic Utility that will generate these patterns on the screen.
2. Using a jeweler’s loupe, pocket microscope, or other magnifying device, identify and 
count each subpixel anomaly:
• Bright subpixel anomaly = subpixel that is always on
• Dark subpixel anomaly = subpixel that is always off
3.Important: Check the number of subpixel anomalies with the following chart:
4. If the number of subpixel anomalies exceeds the acceptable number listed in the 
chart, replace the display panel.
5. If the number of subpixel anomalies is acceptable, explain to the customer that the 
pixel anomalies are within specifications, and no repair is necessary. 
Important:  Do not release the specifications to customers. Instead, inform them that 
a certain number of subpixel anomalies is considered acceptable, and these factors 
apply to all manufacturers using LCD technology—not just Apple products. Acceptable Number of Subpixel 
AnomaliesReplace the Display
BrightDark CombinationBrightDark Combination
up to 8 up to10 up to 15 8 or more 11 or more 16 or more 
						

							© 2003 Apple Computer, Inc. All rights reserved.
 Service Source
Views
Apple Cinema Display 22 LCD (ADC) 
						

							Apple Cinema Display 22 (ADC) Views - 1
 Block Diagram
Block Diagram
Block Diagram
USB Socket
Panel Signal Input
Main Board
LCD Display Panel
J3
J4 J1 J6
Power/Brightness
Switch Board
Backlight Bulb
Connectors Backlight Bulb
Connectors
J5 J2
Inverter
Board
ADC Cable 
						

							2 - Apple Cinema Display 22 (ADC) Views
 Exploded View
Exploded View
Exploded View
Foot  922-3941
Rear Cover  922-5666 (includes
power/brightness switch board)
ADC Cable Assembly
922-5669
USB Cable Assembly
922-5677
Hinge  922-5670
Hinge Cover  922-3945
USB Cover  922-5674
Chassis  922-5667
Inverter Board  661-2809
Inverter Shield  922-5671
Front Bezel Assembly
922-5668
Backlight Bulb Assembly
922-5675
LCD Display Assembly
661-2801
Main Board Shield  922-5673
Main Board  661-2810 
						

							Apple Cinema Display 22 (ADC)
 Screw Matrix
Screw Matrix
Screw Matrix
13 mm Hex 922-5679 Foot (3)
10 mm Hex 922-5680 Rear Cover (18)
10 mm Phillips (black) 922-3541 Chassis to Bezel (4)
8 mm Phillips (flat head) 922-5681 Chassis sides (2)
10 mm Phillips (washer) 922-5682 Chassis corners (4)
6 mm Phillips 922-5135 Main board shield (4)
5 mm Phillips (flat head) 922-5640 USB socket (2)
8 mm Phillips (lock washer) 922-5683 ADC cable clips (2)
6 mm Phillips (yellow, lockhead) 922-5684 USB cable clip (1)
10 mm Phillips (yellow, lockhead) 922-5641 ADC cable bracket (2)
6 mm Phillips 922-5685 Hinge to chassis (4)
4 mm Phillips 922-5605 Inverter board shield (3)
5 mm Phillips 922-5686 Inverter board bracket (2)