Apple MD094LL/A manual Symptoms Quick Check Backlight Issue/No Backlight

Display

Backlight Issue/No Backlight

Unlikely cause: hard drive, optical drive, speakers, camera, microphone

Quick Check

Symptoms		Quick Check
Backlight Issue/No Backlight		1.	Check for Software Update.
•	No image	2.	Verify that System Preferences > Displays >
•	Partial backlight failure
			Brightness control setting is above minimum.
•	Backlight flickers	3.	If no image on built-in display, connect external
•	Display dim
			display to verify if iMac video circuitry is
			functioning. If no image visible on external
			display, go to No Video symptom flow under
			Startup and Power troubleshooting.

Deep Dive

Check		Result	Action	Code
1.	Verify boot chime present and	Yes	Power on self test OK.
	fans running when computer		Go to step 2.
	powered ON. (Reset SMC, clear
	PRAM or reseat Backup Battery	No	Go to Won’t Start Up
	if necessary for proper boot		symptom flow.
	up.)
2.	Verify if image is visible on	Yes	Video is present. Verify system
	built-in LCD panel, with		functionality and return to
	adjustable backlight level.		user, or go to appropriate
			troubleshooting flow.
		No	Go to step 3.
3.	Connect supported external	Yes	External display detected
	display to rear Mini DisplayPort		by system. Video circuitry
	video port (Use known-good		on logic board appears
	MiniDisplay to VGA or DVI		functional. Go to step 4.
	adapters if needed) . Verify if
		No	Go to No Video symptom
	image appears on external
			flow.
	display when system is booted.
4.	Verify if LCD backlight is ON	Yes	LED backlight is functioning.
	by looking for faint glow		Go to step 7.
	from display when viewed in
		No	Go to step 5.
	darkened room with brightness
	set at maximum.

2010-09-09 iMac (27-inch, Mid 2010) Symptom Charts — Display  53