iMac (27-inch, Mid 2010) Symptom Charts — Display 53
2010-09-09
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 under
Startup and Power troubleshooting.
Deep Dive
Check Result Action Code
1. Verify boot chime present and
fans running when computer
powered ON. (Reset SMC, clear
PRAM or reseat Backup Battery
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 is present. Verify system
functionality and return to
user, or go to appropriate
troubleshooting ow.
No Go to step 3.
3. Connect supported external
display to rear Mini DisplayPort
video port (Use known-good
MiniDisplay to VGA or DVI
adapters if needed) . Verify if
image appears on external
display when system is booted.
Yes External display detected
by system. Video circuitry
on logic board appears
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.