Apple MD094LL/A Manuale Utente

iMac (27-inch, Mid 2010) Symptom Charts — Display 

 2010-09-09

Unlikely cause: power supply, hard drive, optical drive, fans, speakers, camera, microphone

Non-Uniform Brightness/Color
•  Brightness not uniform
•  Color not uniform
•  Yellow tint

1.  Verify System Preferences > Displays > Brightness 

slider is set above minimum.

2.  Allow a minute for backlight to reach normal 

operating temperature and output before 

evaluating display.

3.  Visually inspect glass panel for presence of dust, 

cigarette smoke, or other contaminants. Clean 

glass panel if needed.

1.  Determine if color/brightness 

uniformity issue is visible after 

display has warmed up for 

about a minute.

Yes

Go to step 2.

No

Display backlight can take a 

minute to stabilize. Retest. If 

issue still not visible return 

computer to user.

2.  Look at user-provided 

examples showing brightness 

uniformity issue. Determine if 

variation in uniformity appears 

excessive when compared to 

another same-model computer.

Yes

Go to step 3.

No

Demonstrate to user that LCD 

performs similarly to another 

computer of the same model.

3.  Remove glass panel and 

loosen screws securing LCD 

panel. Determine if brightness 

uniformity improves.

Yes

Inspect for mechanical 

interference with screws 

or cables making contact 

with back of LCD. Reseat 

components & cables, retest.

No

Go to step 4.

4.  Remove LCD panel, then 

inspect and reseat backlight 

cables. Determine if brightness 

uniformity improves.

Yes

One or more backlight cables 

were loose. 

No

Replace LCD panel. Run 

Service Display Utility. 

To 

verify the resolution of issue. 

Enter the resulting verification 

code into the “Notes” field 

of GSX and return system to 

customer if repair is complete