Hello everyone 
I have a grape imac g3 400mhz with a dvd drive. I think it is called a DV as it has firewire ports?
I rescued it from the trash a while back and put some TLC into it and upgraded it with more memory (512mb) and went from OS 9.2 to Tiger. The Problem is I have no sound from the internal speakers and the speaker jack on the side. No sound on 9.2 and now no sound on tiger. If I plug a set of speakers or headphones into the 2 front headphones jacks, I have sound, but my internal speakers and speaker out jack on the side near the firewire/usb ports are both dead. I used the search feature on the site and found others having the same problem. I have tried plugging the headphone cord in and out of the ports as suggested in other posts to reset the plug, but nothing works. I also notice in the sound settings the only option I have is headphones for output, I don't have a option to select internal speakers. I saw that it may be a board that has broken it's solder that I have to replace?
For now, I have sound by plugging a set of el' cheapo powered speakers into one of the 2 working front headphone jacks. Any help on which board to replace would be great. I did open up the imac to verify the speakers were plugged in. i even unplugged them and replugged them in for good measure. Nothing in the system seemed disconnected. I am also pretty good at soldering so if it is possible I'd love to save money and repair it myself.
Thanks for the help!
Chris
Thanks for the reply!
I did reset the PRAM, I forgot to mention that. Since my headphone ports do work, I assume the headphone board is good. According to this schematic I should replace the logic board. Is that correct?
Before bothering with replacing the whole logic board, I'd try replacing the logic board's audio-out jack. That jack is designed, much like the headphone jacks on the front, to disconnect audio to the speakers when something is connected to it. My suspicion is that the jack on your machine is broken so that the speakers always remain disconnected (and IIRC, the front headphone jacks take precedence over the side audio jack, so if you had, say, powered speakers connected to the side jack and plugged a pair of headphones into the front, the headphones would get the audio).
Thank you for the reply Dr. Webster!
I will give that a shot. I understand perfectly what you are saying. It must be something stuck or broken in the side jack preventing the speakers from working. Occasionally I will hear buzzing from the front speakers like they want to work, but that's it. I think I will try to replace that jack.
Thank you for the help!
Sorry to resurrect this from the past, but I have some interesting news. I never got around to replacing the board. I just used external speakers. Anyhow, I recently wiped OS X off the iMac and put on MintPPC Linux. I now have sound through the speakers. I don't know if its how the sound is being routed, but even the side jack works now where it did not before. Previously in OS X, I had to plug external speakers in one of the 2 headphone jacks in the front since the speakers were not working and neither was the sound jack on the side.. Thinking i might of freed a stuck jack or whatnot, I wanted to try OS X again. I found another hard drive, reloaded OS X and still no sound. I then took that hard drive out, put the hard drive with MintPPC back in and wala! Sound!
Very strange.