Apple MD094LL/A Manuale Utente

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

 2010-09-09

8.  Verify if high pitch noise varies 

when adjusting brightness level 

up and down.

Yes

Noise seems to be generated 

by vertical sync cable. Inspect 

and replace cable. Replace 

the LED Backlight board if 

problem persists.

No

Noise is from another source. 

Go to step 8.

9.  Verify if noise can be heard 

when computer is set up with 

user seated in normal user 

position. Adjusting brightness 

level up and down may be 

necessary to recreate issue.

Yes

Replace LED backlight board. 

Go to step 9.

No

Noises that are not audible 

from the normal user position 

are considered acceptable. 

10. Verify if noise is still present.

Yes

If noise still present, go 

to 

symptom flow.

No

Issue resolved.