Apple PC Compatibility Card 12-inch card - Manual (Page 29)

15 Installing the Card in a Power Macintosh 7200, 7500, or 7600
Connecting the CD audio cables to the card and the logic board
16 Disconnect the CD audio cable from the Sound In connector on the computer’s
logic board.
Be sure to pull the plug, not the cable.
This is the same cable you disconnected from the CD-ROM player in step 6.
You will be replacing it with new cables that came with your PC
Compatibility Card.
Disconnect the CD cable from the connector
on the computer’s main logic board.