Apple 2009 iMac - Page 43

iMac (21.5-inch, Late 2009) Symptom Charts — Display 43
2010-11-18
Display
Backlight Issue/No Backlight
Unlikely cause: hard drive, optical drive, speakers, camera, microphone
Quick Check
Symptoms Quick Check
Backlight Issue/No Backlight
• No image
• Partial backlight failure
• Backlight ickers
• Display dim
1. Check for Software Update.
2. Verify that System Preferences > Displays >
Brightness control setting is above minimum.
3. If no image on built-in display, connect external
display to verify if iMac video circuitry is
functioning. If no image visible on external
display, go to No Video symptom ow.
Deep Dive
Check Result Action Code
1. Verify boot chime present and
fans running when computer
powered ON. (Reset SMC and
clear PRAM if necessary for
proper boot up.)
Yes Power on self test OK.
Go to step 2.
No Go to Won’t Start Up
symptom ow.
2. Verify if image is visible on
built-in LCD panel, with
adjustable backlight level.
Yes Video present. Verify system
functionality and return to
user or go to appropriate
troubleshooting ow.
No Go to step 3.
3. Connect supported external
display. Verify if image appears
on external display when
system is booted.
Yes External display detected by
system. Video circuitry on
logic board functional.
Go to step 4.
No Go to No Video symptom
ow.
4. Verify if LCD backlight is ON
by looking for faint glow
from display when viewed in
darkened room with brightness
set at maximum.
Yes LED backlight is functioning.
Go to step 7.
No Go to step 5.