Jason’s aux audio input to the Mazda stock head unit without soldering
I finished the aux input hack that was discussed earlier with soldering wires to the circuit board of the head unit.
http://www.whatsmyip.org/ipodrx8/ and
http://mymazda3.patricktam.net/project_aux_input.asp
After finishing soldering I figured out an easy way to connect the wires without soldering. So here is a non-soldering aux input hack. This will be of interest to people who are not comfortable soldering. Follow all the steps in the original hack to get to the circuit board for the audio connector for the cd player.
The non-solder hack
This hack requires a little more disassembly. Unscrew two screws along the side where the audio connector is which holds the main circuit board down and two screws along the side to allow you to remove the small cd connector circuit board from the main circuit board. There is a white connector with 15 pins that pass the signals through to the main circuit board. This connector is what will allow attaching wires to the audio channels. The main board side of the connector has holes to accept the pins from the cd connector circuit board. Small wires can be inserted into the holes for the right, left channel and the sound ground. Reassemble the cd connector circuit board to the main board. The white connector with pins is pressed into the connector with holes and will make contact with the wires in the holes. The wires will stay in place by being sandwiched between the two pieces of the white connector.
Finishing up
It is a good idea to use an ohm meter to make sure you have contact between all contacts before putting everything together and finding out after it is reinstalled that a wire is loose or not connected. Reassemble; don’t forget to screw the circuit board back down before reassembling.
Aux input is wired up!
The wires inserted in to the connector holes need to be small enough to allow the pins to fit along with them in the holes and so the connector closes enough to make contact through the connector. I used stranded 22-gage wire, which could deform around the pins and it worked. I fed these pieces of wire to the bottom of the head unit where I attached the cable cannibalized from a pair of headphones I was not using.
Now you have an aux input for free with no soldering.
Optional variations
The hacks described so far requires a cd of silence to play while using the aux input and it has been mentioned that the audio levels are reduced with both the audio signal from the cd player and aux input running at the same time.
The solution
A switch can be added to disconnect the audio signal from the cd player and connect the audio signal for the aux input resulting in clean audio at normal sound levels that works with any cd not just a silent one.
I came across the hack that was used for an external cd player at the following web page
http://www.mattgilbert.net/carstereoauxinput
Since the cd player of the Mazda is integrated into the head unit it didn’t seem possible to apply this hack.
I figured out a way to do it.
Switch audio with an integrated cd player
This hack combines the original soldering hack and the non-soldering hack. One set of audio signals for the cd player will come out at the soldering point. Wires that come from the aux input jack will be the other set of audio that will be at the second position of the switch. Wires inserted into the holes of the white connector between the main board and the cd connector circuit board will serve as the wires that will carry the selected audio signals to the head unit.
Where to create a break in the signal path?
In order for the signal to switch back and forth between the two sources, a break in the original signal path needs to be implemented. I thought about scratching off the trace on the circuit board but I wanted something that could be reversed and non destructive. This lead me back to the white connector with the pins. I bent over the pin associated with the audio signal lines that I wanted to break (L and R, I left signal ground alone) so that the hole in the connector would have a wire and no pin coming out of it, thus bypassing the original signal path. It is reversible by bending the pin back up.
Type of switch
Switching the L and R channels requires a two-position two-pole switch. This hack may also work if only the signal grounds of each source are switch and it would require only a single pole switch. I would like to find a switch that is small and looks nice or possibly a two-position button would look better.
I am still looking for a good place to mount the switch, possibly in the ash try or the switch panel on the drivers left side.