Black Box AC470A Manual page 10

INTERNAL AUDIO SYSTEM
Figure 4.3. Connecting the Internal Audio System Unit.
Step 7
Plug one end of the Mono Cable (provided) into the PC Speaker Input
(Mono) jack on back of the Internal Audio System unit. Plug the other end
into either the right or left prong of the PC motherboard connector labeled
SPEAKER. See Figure 4.3.
NOTE
You can verify whether you've attached to the correct SPEAKER prong by
listening for an amplified beep after you switch on power to the computer
(Step 9). If you do not hear the beep, repeat Step 7 but attach the Mono
Cable motherboard connector to the opposite-end SPEAKER prong.
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