Apple MacBook Pro 17-inch (original, Core 2 Duo, 2.4GHz, Late 2007 CTO, Early 2008, and Late 2008) - Manual (Page 189)

MacBook Pro 17-inch (original, Core 2 Duo, 2.4/2.6GHz, 2008) Troubleshooting — Hardware Symptom Charts 189
the pins as directed in Kbase article 303240: Use and cleaning of power adapter with
MagSafe connector.
Remove the battery and connect the power adapter. If the adapter turns on and boots the 4.
system, replace the logic board.
Remove the battery and connect the power adapter. If the adapter turns on and boots the 5.
system, replace the logic board.
Sound
No sound is audible but the Speakers section of the Sound system preference pane
indicates an external device is plugged in (to the headphone jack or USB ports)
If there is nothing plugged into the headphone jack or USB ports, the Output tab of the 1.
Sound system preference pane should be set to the internal speakers.
If not, and if nothing is plugged in, try plugging in headphones or external speakers. Restart 2.
the computer. Remove the device.
Reset PRAM. (After restart, hold down the Command-Option-P-R keys until you hear the 3.
startup chime at least one additional time after the initial startup chime).
If the system continues to indicate a phantom device is plugged into the system, replace the 4.
left I/O board.
Replace the logic board. 5.
No sound from speaker(s)
Use Software Update to verify that the latest audio update has been installed. 1.
Press F10 (with the fn key pressed and then not pressed) to verify that mute mode is not 2.
enabled.
Press F11 or F12 (with the fn key pressed and not pressed) to check the volume setting. 3.
Verify that no external speakers or headphones are plugged in. 4.
Check the speakers tab on the Sound control panel to confirm that the software is correctly 5.
detecting that there are no external speakers or headphones connected. If so, use the
previous troubleshooting procedure.
Shut down the computer and restart. 6.
Reset PRAM. (After restart, hold down the Command-Option-P-R keys until you hear the 7.
startup chime at least one additional time after the initial startup chime).
Verify that the speaker cable is properly connected to the left I/O board. 8.
Check the speaker cable. Verify left and right cable connections. 9.
Verify sound output with known-good headphones or external speakers. If audio is heard, 10.
replace the speaker assembly.