[IanCT]

And I know what you're thinking, but no other cables were disconnected.

I swapped the DVD-ROM from my iMac 400 DV and my G4 Cube, now the iMac internal speakers do not function at all. (Cube works great) I can use headphones to verify sound will play, but other than that the speakers don't function. In OS 9 I can select headphones or speakers, but the speakers aren't the right icon and I remember them displaying the actual iMac speaker grille. In OS X (Panther) nothing other than Headphones is available.

I have reset PRAM, pressed the CUDA for at least 15 seconds, and haven't been able to restore internal speakers.

I have initialized the drive and am re-installing the OS now, see if that works, short of that I'm out of ideas.

[TangoCharlie]

I'm not being funny, this happens to me frequently, but press the mute key on your keyboard.
I once spent half a day trying to figure out why my Mac was quiet! Yes, I'd accidently hit the mute key which is near the eject key!
Logically the work you carried out should not effect the speaker sound.
Tc

[IanCT]

Originally Posted by TangoCharlie

I'm not being funny, this happens to me frequently, but press the mute key on your keyboard.
I once spent half a day trying to figure out why my Mac was quiet! Yes, I'd accidently hit the mute key which is near the eject key!
Logically the work you carried out should not effect the speaker sound.
Tc

LOL no that wasn't it. Believe me, I wish it were. I did figure it out though.

Turns out when I pulled the bottom casing off, it wiggled the headphone PC board and loosened the solder points on the board from the dual headphone jacks causing the problem. I tried to resolder them but the traces had pulled away from the board. After a few hours of searching the internet for schematics (found a website with lots of REAL tech manuals, not the lame user manuals) all I could find was a general picture of the headphone board, not a wiring diagram so I could bypass it.

I wound up studying the PC board and the wiring assignments and soldered a jumper across three pins from the ribbon connector on the board itself and the sound has been working ever since. Headphone jack will never work again but that doesn't bother me one bit, since I never use it. It's in my daughters' room now as their computer for kids games. And they "must" have sound...