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Discussion Starter · #1 · (Edited)
A while back I decided on adding an AUX input to my 2002 6, it wasn't that easy, but I promised to make a tutorial on how to do it, so here it is :)

N.B.!!!
This requires some soldering skills and basic knowledge in electronics, as we will be modifying the HU.
Bear in mind that most electronic devices are ESD sensitive, even the slightest static discharge could damage your HU! The IC we will be tampering with is located really close to the CPU of the HU, I'd recommend doing this in ESD safe enviroment ;)
All in all, if you're not sure about weather you can do this, either ask someone do do this for you, or simply don't take the risk at all ^^
If you do decide to give this a try, do it at your own risk!

You will need:
2 x 10uF 16V electrolytic capacitor
2 x 47kOhm 0.125W resistor
2 x 100kOhm 0.125W resistor
2 x switch with fixation (I guess it's called "latch type", but I might be wrong)
Some wires
Soldering iron
Montage board
Voltage of capacitors and wattage of resistors is the minimum value. Meaning the values mustn't be less than these, but can be higher.

How this works:
I guess I'll start with explaining how all of this works :) So, there is an input selector on the HU (IC201), which is abviously used for selecting inputs - Radio, CD or the Tape/MD module, however, only two outputs are used, that is, if your TAPE/MD button is not working. We wont get the button to work, but we will attach our own button for activating the AUX input. As you will see later on in the wiring diagram, there are two transistors which determine what output will be used. A signal is fed to the bases of these transistors from the CPU of the HU and they basically work as switches or somewhat as a logic gate. So, depending on how the signals are fed into the bases of the transistors, they output two signals, it's either logical High (as binary 1) on Q510 or Q511 output (that's the collector in this case), or both outputs. You could use just one switch on Q511, as I'm using a switch for each transistor and one of them won't do anything. Then again, it's been a while since I did it all on my HU, and I don't really remember wether it's the switch attached to Q511 or the one on Q510. Sorry about this, lol. As for the input selector, depending on the output signals of the two transistors, it selects radio or cd input and feeds it to preamp. As you will see in the wiring diagram, there are two pins that are not connected to anything - that's the third input we'll be using for our AUX.
English is not my native language, so I apologize if something's not clear :D If so, please feel free to ask ;)
We'll be working on this part of the HU:


First step. Making a filter board.
You can skip this step, but I wouldn't recommend doing that, lol. This is a simple circuit that filters out everythng unneccesary from the audio signal we'll be feeding into the input selector (IC201).
Here's a schematic:

Lin and Rin are Left and right inputs, Rout and Lout are the outputs. You'll have to connect outputs to the IC201, 3.5mm audio jack goes to Rin and Lin. GND is common ground. As we're using electrolytic capacitors, make sure that that the cathode is where you're feeding the signal. More simple way to put it - make sure that the negative side (Anode) of capacitors is connected to the 47kOhm resistors. (+ => Cathode, - => Anode)
Here's some pics on how I did my filter board:



I used SMD resistors, as I had them on hand, but you can use the conventional kind as well - it doesn't matter.

Second step. Remove the center console.
I'm not doing a how-to on this one, there's plenty of info on how to do this.

Third step. Remove the actual HU from the center console and open it up.
I'm not doing a tutorial on this one either, it's pretty easy + I bet someone has already done a tut...

Fourth step. Add the filter board to input selector.
Just solder the output wires from your filter board to the pins of input selector as follows:

And a pic on how I did it:


Fifth step. Switches.
As i mentioned before, you could add just one of these, but I'm not sure which one is the one that actually works... Sorry for this.
So, as you might have already figured out, we'll need to interrupt the signal from the CPU to the bases of these transistors (see the wiring diagram in previous step.) - we'll need to carefully make a cut to do this. After you've made the cuts, scrape off the protective coating from the wires, as we'll need to solder an external wire there, but to do that you have to have a clean copper wire without any coating on it. Also, I'd recommend testing weather the cuts are actually interrupting the signal - do this with a multimeter set on resistance. Put one probe on the base of a transistor, the other on the "CPU side" of the wire (where you scraped off the coating). If resistance shows up as infinite or OL or 1 (depends on multimeter), you're good, if it shows up as zero or close to zero, redo the cuts.
Solder wires to bases of Q510&Q511. Then carefully solder wires to where you removed the protective coating. Make sure nothing is short circuited. I used short wires at first, ran them down to my filterboard and soldered extensions with the fixating switches there. I did this not to rip off the wires I soldered, as the soldering spot is really tiny and the solder itself is fragile. Also, I used silicone and industrial tape to fasten the wires in the MOBO of HU.

I recommend making knots on one pair of the witch wires, not to mess it all up once you've put the HU back together. Also, I'd recommend using flux when soldering all the wires. Using flux makes the solder cleaner, mechanically more stronger and more conductive.


Sixth step. Putting it all back together.
Before this, make sure nothing is short circuited! Also make sure that the wires you soldered are not coming off the mobo!
You can run the wires out of the HU as you may please, I ran them through an opening in the 16pin connector:


As I mentioned before, I used shorter wires for the switches at first, ran them down to filterboard, soldered them on the filterboard and added extension wires with already soldered switches there. I won't be much of help when it comes to switches, I mean, I used some old soviet ones I had lying around, you're probably going to use new ones and the pinout on those most likely differs from mine.
The switches I used:


Now would also be a great time to add the 3.5mm jack (or whatever jack you're going to use for aux) to the filterboard. That is, if you haven't already done so ;) Makse sure the wires you're using are long enough - you should probably think about where you want your jack to be in the actual car. Used a female jack, drilled a hole in the plastic that covers up the external media modules slot and fitted it there. As for the switches - they're just hanging around near to the gas pedal for now, I haven't had the time to buy a decent switch and fit it somewhere to make it look factory made.

Seventh step. Precautions.
Once you've put your HU back together, you probably have your filterboard hanging somewhere out of it, at least mine did. To make sure it doesnt get short circuited or doesn't short circuit something else, I just used industrial tape and silicone to cover all the conductive spots.

If you think of a decent spot where to fasten the filterboard and a decent way on how to do it, please do it, as mine is just hanging out there, behind the HU.

Eighth step. Final touches.
Put your modified HU back on the center console. When putting the center console back in, be careful not to rip off any wires. Also make sure you can access both of the switches. Once you've fitted the center console back in, you're done :)

Activating the AUX
You can activate the AUX input by using one of the switches. The info display won't show that external device is being used - if you were listening to the radio when switched to AUX, it will still display that radio is playing, but, as you've activated the third input on the input selector, you won't be hearing radio anymore - you'll be hearing whatever is connected to your AUX input.

I got the idea from these forums:
AUX âõîä Mazda 6 (2004) äîðåñòàéë - Óêðàèíñêèé Ìàçäà Êëóá :: MazdaClub.UA

Here's a link to more pictures of my HU. Don't be confused though, at first I tried removing the transistors - that wasn't such a good idea as my AUX was working, but I wasn't able to switch to either radio or CDs. Btw, this was the mothod the guy on ukrainian forum used.
https://www.dropbox.com/sh/vguc75jrndhufre/mpIruV3SSl


If everything is done right, I can guarantee that it will work ;)
I hope this will be helpful to some of you :)
Also, I might have forgotten to mention something, or something I did mention was unclear. If that's the case just feel free to ask ;)
 

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Discussion Starter · #3 ·
If this works, great. But wow, a lot of work IMO to get an AUX input.
It does work ;) The volume might be a bit lower than when listening to cd or radio, but it works just fine and the quality of sound is also pretty neat.

This DIY is for those of you who don't want to spend money on sylfex or something similar. As for my HU, sylfex wouldn't even work. I guess they used somewhat different HUs in early european models.
 

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It does work ;) The volume might be a bit lower than when listening to cd or radio, but it works just fine and the quality of sound is also pretty neat.

This DIY is for those of you who don't want to spend money on sylfex or something similar. As for my HU, sylfex wouldn't even work. I guess they used somewhat different HUs in early european models.
Which, just to be aware, means this may not work on the US models as well.

It's awesome that you got it working, but for the time it would take to do this an the risk to your head unit I think spending the $60 on the sylfex would be the better way to go. Sounds like this option wouldn't have worked for you so it's awesome that you figured it out though. Nice walkthrough. :)
 

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Discussion Starter · #5 ·
Which, just to be aware, means this may not work on the US models as well.

It's awesome that you got it working, but for the time it would take to do this an the risk to your head unit I think spending the $60 on the sylfex would be the better way to go. Sounds like this option wouldn't have worked for you so it's awesome that you figured it out though. Nice walkthrough. :)
I guess the difference between early european models and US models is that the external filterboard I made is not on the HU. I can see where it was ment to be, but there were no components there, therefore the external module connector is not connected to input selector. And that's why sylfex wouldn't work on my HU.

When I was analyzing the circuit diagram of the HU I actually found that the CPU on there supports radio, CDs, external module and an actual AUX... So at least 4 different sources.

Anyhow, I'm now probably the only one with an '02 6s and a working AUX :D
 

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Pretty nice tutorial. But like DefStatic said, it's too much work (atleast for me :D)
I bought Grom audio aux/usbstick/android adapter to my 02 Mazda 6 and it works awesome, just had to solder one jumper to circuit board.
 
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