8.

Verify if high pitch noise varies

Yes

Noise seems to be generated

X03

 

when adjusting brightness level

 

by vertical sync cable. Inspect

 

 

up and down.

 

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

Yes

Replace LED backlight board.

M04

 

when computer is set up with

 

Go to step 9.

 

 

user seated in normal user

 

 

 

 

No

Noises that are not audible

 

 

position. Adjusting brightness

 

 

 

from the normal user position

 

 

level up and down may be

 

 

 

 

are considered acceptable.

 

 

necessary to recreate issue.

 

 

 

 

 

 

 

 

 

 

 

10.

Verify if noise is still present.

Yes

If noise still present, go

 

 

 

 

to Noise/Hum/Vibration

 

 

 

 

symptom flow.

 

 

 

 

 

 

 

 

No

Issue resolved.

 

 

 

 

 

 

2010-09-09

iMac (27-inch, Mid 2010) Symptom Charts — Display  57

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Apple MD094LL/A manual When adjusting brightness level, To Noise/Hum/Vibration, Symptom flow Issue resolved