Guys, thank you so much for all this help and sharing. I tried so many things, and finally it worked! Tried blowing air into the plug, sticking paper clip and qtip with alcohol.
bruensk, thank you so much for the drawing.
My solution for "No Sound Output to MacBook Speakers" - Re-route Sound Input / Output
I have had this problem on my MacBook Pro, and tried EVERYTHING Apple & Forums suggested - SMC reset, PRAM reset. Apple advised me to send it in for servicing. Since it isn't covered by warranty, I didn't want to do that.
If you do not want to pay Apple to fix your MacBook optical sound jack hardware, you can overcome the problem with this procedure I came up with myself, which overcomes the hardware failure caused by the headphone jack optical sensor thinking something is plugged in there when there isn't.
Ironically, this solution requires a jack be inserted into the headphone jack. Annoying, but workable and free.
Step 1. Plug headphones in (dont worry, you wont use them)
Step 2. Change System Preferences -> Sound -> Change Internal Speakers to an Input!
Step 3. Done!
Obviously when you do want to use the headphones, you must revert this setting!
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I suggest that you do this with the computer on and music playing (like iTunes), so that you immediately see if you did it.
Try plugging some headphones in (or your Toslink lead, if that's what you used) and slightly wiggling the lead as you pull it out. (be gentle though)
I found that sometimes (pretty rarely) my Powerbook would get stuck on the headphone setting after listening to headphones on it, and this sorted things out. Only seemed to do it when it was new, it's fine now though.
red light fix
I found a fix for the red light problem. I'm not sure if I like it, but it works. After reading forum thread after forum thread of users that had this problem, I found a dude who fixed his jack with a rubber ended bobby pin. It seems a sensor gets bent (?) and the system thinks your digital external line is still plugged in. I took the butt end of a matchstick and tickled inside the jack. My red light went out. My internal speakers work again. Whatever.
Guys, thank you so much for all this help and sharing. I tried so many things, and finally it worked! Tried blowing air into the plug, sticking paper clip and qtip with alcohol.
bruensk, thank you so much for the drawing.