Apple MD094LL/A Manuale Utente

iMac (27-inch, Mid 2010) Symptom Charts — Input/Output Devices 

 2010-09-09

5.  Inspect microphone cable 

routing and verify if cable is 

pinched or damaged.

Yes

Replace rear housing 

(microphone cable not 

available separately).

No

Go to step 6.

6.  Record sound sample using 

GarageBand or iMovie. Verify if 

sound quality of sound sample 

is normal during playback.

Yes

Microphone circuitry OK. 

Return system to user.

No

Replace logic board.

Unlikely cause: LCD display, power supply, hard drive, optical drive, fans

Distorted Sound
•  No audio from one or both 

speakers.

•  Audio from speakers distorted

1.  Go to System Preferences > Sound > Output. 

Verify that sound output device is set to internal 

speakers and that balance control is set to the 

center position.

2.  Obtain known-good high-quality sound file or 

use iTunes Store sound samples to evaluate 

sound quality. Verify suspect sound files on 

another system to determine if distortion is 

caused by computer or sound file.

3.  Set volume control to mid-range. Overdriving 

built-in speakers can cause distortion.

1.  Go to System Preferences > 

Sound > Output. Set speaker 

balance 100% to LEFT speaker 

and play a known-good sound 

file. Verify if sound is generated 

by LEFT speaker and that sound 

quality is acceptable.

Yes

LEFT speaker and amplifier 

circuitry OK. Go to step 2.

No

Distortion detected in LEFT 

speaker. Set Balance slider to 

middle position. Go to step 3.

2.  Set speaker balance 100% 

to RIGHT speaker and play a 

known-good sound file. Verify 

if sound is generated by RIGHT 

speaker and that sound quality 

is acceptable.

Yes

RIGHT speaker and amplifier 

circuitry OK. Set Balance slider 

to middle. Go to step 3.

No

Distortion detected in RIGHT 

speaker. Go to step 4.