Schizophrenic MBP sound issues

[cleo]

I have a 1-year-old MBP (2.4 GHz Core 2 Duo). 95% of the time it's a desktop machine, with a set of JBL Creature speakers plugged into the headphone port.

In January I was traveling and tried to play a CD, and got no sound. I checked to make sure the output settings were correct (they were) and just figured my internal speakers were bust. I got home, plugged in my external speakers, and everything was fine, so I promptly forgot about it.

Then yesterday I took the MBP outside to work, and when I came in, the oddest thing happened:

I plugged my speakers back in, and the sound started coming through my internal speakers. Stranger still, when I unplug the speakers, there's no sound at all!

I've done what little troubleshooting I know how to do (I've been blessed with happy Macs through the years):

- Problem persists in the Guest Account, so if it's a pref file issue, it's at the system level.
- Multiple logouts and restarts haven't worked.
- All software and firmware is up to date.

This is the craziest thing I've ever seen. Any ideas would be much appreciated!

 

[Blue Velvet]

Sounds like a hardware issue.

The headphone jack contains switches that cut the feed to the main speakers when something is plugged in. If these get bent or start malfunctioning, then all sorts of problems start happening e.g. sound in one channel or the other stops working, the cut to the main speakers stays on or doesn't work as it should etc. None of these problems will show up in the OS.

The tolerances can be pretty fine. If you try different plugs like headphones and external speakers the effects can vary, depending on their slight differences in sizes.

Having the JBL Creatures plugged in 95% of the time for a year or so may have caused the contact pins within the jack to settle into a new place and lose some of their springy responsiveness.

 

[cleo]

Thanks, BV!

For the record (and future googlers), after readng your post I unplugged/replugged the speakers a couple times, and they started working as expected, so your diagnosis is spot-on.

I'll wait till after the holidays and take it in to a Store to see if they recommend any hardware repairs.