Internal Speaker issue on MBP 17″, no red light

April 5, 2011

It turns out that lots of MBP models have a well-known issue with the headphone port, and this can cause the internal speakers to become disabled. Actually, they’re disabled as a side-effect of digital output being enabled. The headphone port is used for both electrical and optical connections, and the internal switch managing this can sometimes enter the “optical connector present” state for no apparent reason.

Here’s one thread describing this issue, and Google turns out many more.

However, the reason that I’m writing this is that my machine (2010 17″ MBP) seems to suffer from a variation of this problem. All descriptions of the issue I found were rather old, and in all cases it was reported that the red light (ie. the optical signal stream) was turned on when the internal speakers were disabled. On my machine, the red light was visible only some of the time.

Doing a software update, a reboot and even an SMC reset did not help. I eventually fixed the issue by moving the headphone jack slowly in and out of the port while wiggling it a little bit. It took maybe 15 tries before it worked…

To monitor your (lack of) progress, open the System Preferences, go to the Sound pane and select the Output tab.

  • In the broken state, the topmost item will read “Digital Output” and a red light may or may not be visible from the headphone socket
  • When the headphone jack is inserted, this should change to “Headphones”
  • The non-broken state is “Internal Speakers”. This is when you have managed to clear the switch (HW or SW, I don’t know) that is stuck in the “optical connector present” state.
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