Apple MD094LL/A Manuale Utente

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

 2010-09-09

Unlikely cause: power supply, hard drive, optical drive, fans, speakers, camera, microphone

Vertical/Horizontal Lines
•  Vertical lines
•  Horizontal lines

1.  Boot from install DVD to determine if potential 

software issue exists.

2.  Verify if issue is visible on an external display.

1.  Boot from Install DVD and 

verify if issue is still visible:

•  Flickering image
•  Horizontal bands of static 

intermittently appear

•  Dock and / or menu bar shift 

positions

•  Display intermittently flashes 

on / off

Yes

Go to Flickering issue, go to 

Noise / Unstable Flickering.

No

Issue likely caused by 

software or driver issue. 

Troubleshoot for software 

issues. Make sure all firmware 

and software updates have 

been installed.

2.  Verify if issue is visible on an 

external display attached to 

mini DisplayPort.

Yes

Issue NOT caused by internal 

LCD. Go to step 3. 

No

Go to step 4.

3.  Remove video card and inspect 

connector for damage or 

corrosion then reinstall. Verify if 

issue still occurs.

Yes

Replace video card.  

Go to step 5.

No

Issue likely caused by poor 

video card connection. 

4.  Disconnect DisplayPort cable 

between LCD display and logic 

board, and verify if there is 

damage to cable or connectors.  

 

Repeat with vertical sync cable 

connected between LCD panel 

and LED backlight board.

Yes

Replace DisplayPort cable 

and vertical sync cable or any 

other damaged part/module. 

Go to step 5.

No

Reinstall DisplayPort cable 

and vertical sync cable.  

Go to step 9.

5.  Verify if issue is still present.

Yes

Replace logic board. If video 

card was present, reinstall 

original video card.  

Go to step 6.

No

Issue resolved.