iMac Doesn't Detect Headphones

[Betelgeuse]

I have a ~year old 24" iMac (2.8 GHz Core 2 Duo) that I just suddenly started having a problem with. I use headphones pretty regularly and they are almost always plugged into the headphone jack. Recently, I lent my headphones to someone and, when I plugged them back in, the machine doesn't detect them. The audio works just fine coming out of the internal speakers, it's just that it *always* comes out of the internal speakers, no matter if the headphones are plugged in or not. I took a look at the Sound Preferences panel and, sure enough, it doesn't detect the headphones as plugged in (just the internal speakers). Does anyone have any suggestions on troubleshooting?

I'm not sure it matters, but I did just recently upgraded to 10.5.6. The headphones worked after the upgrade, but it may be that this is the first time they were *re*plugged in after the upgrade.

 

[hughvane]

You say the headphones were lent to someone, and they no longer worked after they came back, alongside of which was an upgraded OS. I don't think the two are related.
1. The headphone plug itself may be damaged, or more likely, it was pulled (yanked), accidentally or otherwise, from an audio port by its cable. Most audio plugs are molded so you can't readily tell if there's a damaged, loose or broken connection within. Can you try the headphones with a different audio unit, eg. a mini stereo set or radio?
2. Unlikely, but maybe the audio port in your Mac has become permanently stuck closed ie. sound diverted to the speakers. When you push an audio plug in, the switch inside is opened - or should be. You may need to probe about inside the audio port with the headphone plug, but switch your Mac off completely before doing so.

 

[katwonderful]

hey, i have the same problem posted. but i never lent my headphones to anyone. i tried 2 different headphones and it still has the same problem, computer can't detect the headphones. i'll check to see if your solution works. thanks.