iMac (21.5-inch, Late 2009) Symptom Charts — Startup and Power 39
2010-11-18
Corrupted Video
Unlikely cause: power supply, hard drive, optical drive, fans, speakers, camera, microphone
Quick Check
Symptoms Quick Check
Corrupted Video
• Text and graphics appear fuzzy
• Image corrupted
1. Verify Mac OS X version installed is the build
number supported on the hardware. Make sure
customer didn’t migrate over their old version of
Mac OS. See kBase #TS3101: iMac (Late 2009):
Using the correct Mac OS X system software.
2. Set System Preferences > Displays to native
resolution of LCD. Non-native resolutions are
unable to produce optimal clarity.
3. Clean outside surface of glass panel.
4. Make sure all relevant software updates have
been applied. Graphics driver updates may be
included with software updates.
5. Boot from install DVD or another known-good
volume to determine whether a potential
software/driver issue exists.
6. When issue occurs, take a screenshot of the
display (Command-Shift-3). View screenshot le
on a known-good computer. If image corruption
can be seen in the screenshot then issue is with
the video drivers, software, or video/logic board. If
issue cannot be seen in the screenshot then LCD
panel and LVDS cable should be tested further.
Deep Dive
Check Result Action Code
1. Boot from Install DVD and
Verify if issue is still visible.
Yes Go to step 2.
No Issue likely caused by
software or driver issue.
Troubleshoot for software
issues. Make sure all software
updates have been installed.
2. Verify if issue is visible on an
external display.
Yes Issue is NOT caused by
internal LCD display.
Go to step 3.
No Go to step 6.
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