iMac (27-inch, Mid 2010) Symptom Charts — Display 68
2010-09-09
Non-Uniform Brightness / Color
Unlikely cause: power supply, hard drive, optical drive, fans, speakers, camera, microphone
Quick Check
Symptoms Quick Check
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.
Deep Dive
Check Result Action Code
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 Apple
Service Display Utility. To
verify the resolution of issue.
Enter the resulting verication
code into the “Notes” eld
of GSX and return system to
customer if repair is complete
L07