first thing I did was open my xbox and use my multi meter to find the left and right audio positive pins on the motherboard, I did this by hooking my AV cable into the xbox then I touched 1 probe to the long tip on the audio cable then I went through all the pins until I got 0 resistance. Next I did the same for the other audio cable.
After I found the left and right audio pins I cut open a male to female 3.5mm wire and found 3 wires inside, red was the right, white was the left, and the bare wire was ground
After connecting the wire in the picture above I turned on the xbox with some headphones plugged into the newly installed jack and heard the sound of the xbox starting, now it was time to fit the jack into the case.
I cute up the wire into a smaller section, (it was a 12 foot cable and I knew I would not need all of it) and put 2 wires on the audio pins and fed them through a hole on the motherboard near the south bridge chip
Again white is the left and red is the right channel. Next I decided where I wanted the cable to be on the case, I decided on next to the DVD-ROM drive.
and check to see if it would fit between the side grill and the metal shroud that holds the motherboard
Perfect fit next I connected all the wires, red to red, white to white, and the ground I soldered to the top of the memory unit shroud.
Next I cut a hole in the case for the jack
Now that everything was wired up and installed I put the xbox back together, plugged in my HDMI cable and PC speakers and got no sound from the speakers... Turns out the xbox will detect if the AV able is connected and if not will not output any audio to the pins I soldered to so I found a pinout for the AV port and found that I need to bridge 2 pins to make the xbox think it had a component cable connected, pin 26 and 28.
I used a jumper wire to connect the 2 on the AV port itself, I did not take a picture so I will explain it the best I can.
On the AV port there are 30 small holes about the size of 30 awg wire, 15 on top and 15 on the bottom, on the bottom row starting at the right I inserted a wire into the second and third holes, hooked everything back up and now I have sound from my PC speakers.
I used a Falcon motherboard in this project if you plan to do this to your xbox make sure to use a multi meter to find the left and right audio pins.
Edited by snake3, 22 June 2010 - 01:26 AM.