Specifications

Troubleshooting Symptom Charts/Video - 8
No display, or dim
display, but computer
appears to operate
correctly
1 Remove any connected peripherals.
2 Try known-good power outlet, power adapter and power cord.
3 Press the F2 (with the fn key pressed and not pressed) to
increase the screen brightness setting.
4 Reboot the computer—hold down the Control and Command
keys and press the Power button, or press and hold the Power
button for 5 to 10 seconds to shut down the computer, then
press the Power button to restart.
5 Connect an external display, and check for video on external
display.
• If video is fine on external display, replace LCD panel.
• If video symptom is same on external display, replace logic board.
6 Verify backlight cable and LVDS cable connections are seated
properly and that the cables are not damaged (refer to display
assembly replacement instructions).
7 Replace display assembly.
8 Replace logic board.
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.
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