Headphone jack on 24" iMac does not function

[kilowatt]

Greetings,

When in plug in to the headphone jack on our 24" intel iMac, the audio continues to come out of the built-in speakers. I have tried plugging in all sorts of headphones, as well as amplifiers and such.

The System Preferences, as well as the Audio MIDI Setup continue to only say "Internal Speakers" as my only output option.

I have tried turning off the machine and disconnecting power and all peripherals for fifteen seconds, as recommended on one web site, and this had no effect.

I am considering a fresh OS install on an external drive, but I figured I'd ask here before I did that.

Originally, the iMac ran 10.4.x, and the jack worked. At some point, before I upgraded to 10.5, the jack stopped functioning. Now I am runing whatever the latest 10.5 release is.. probably 10.5.4.

Any help would be greatly appreciated!

Thanks!

[kilowatt]

Does anyone know,

if I boot up from my 10.5 update CD, and I plug in head phones, should the speech come out of the headphones, or continue to come out the speakers?

Mine comes out of the speakers, not the headphones.

You can tell the installer to speak some dialog boxes in the install, before it installs anything. It's under one of the menus.

If someone could try this for me, that would really be great!

Thanks!!