AUX in on a Stock '05 Head Unit w/o Silent CD (The Project)

[mcwiggin]

Ok so this thread is results and findings on coming up with a way to get AUX in on a Stock 2005 Subaru Legacy Head Unit.

Thanks to drcaveman in finding the service manual for the 05/06 headunit which has complete circuit schematics for the head units.. To download the manuals:

Manual 1 can be downloaded here (0505cqef1561l.pdf)
www.mcwiggin.com/subaru/0505cqef1561l.pdf (http://www.mcwiggin.com/subaru/0505cqef1561l.pdf)


Manual 2 can be downloaded here (0505cqef1560l.pdf)
www.mcwiggin.com/subaru/0505cqef1560l.pdf (http://www.mcwiggin.com/subaru/0505cqef1560l.pdf)

I had been posting under that topic but I think that it would be best to start a new topic to keep this information and my progress organized.

So here is what I have so far.

// COPIED FROM OTHER TOPIC

Ok I think this is going to pretty easy actually! I looks like we can do this without and board mods at all! If we bring pin 2 on CN402 to ground that should enable satellite signal according to the main CPU. Audio comes down pins 4 and 8 and I am not sure yet how the left and right channels are deciphered. From there I think the satellite selector button should probably work to select satellite as a source. The button does exist (its that blank spot on the input selector switch that goes 4 ways.) You can make it work by opening the stereo and removing the piece of plastic that prevents you from pushing the button. I haven't tested this yet.. but it should work!

I will post results as soon as I test it!


If someone gets a chance let me know what they think is going on with the left and right audio signals signals (C402 - C405 are 1uf caps)


http://www.mcwiggin.com/subaru/SatInput.png

Block Diagram showing the connections to CN402... As you can see there is more here than just the steering wheel controls.

http://www.mcwiggin.com/subaru/Block.png

[mcwiggin]

Update... I removed the radio and tried grounding PIN 2 of CN402. To my surprise the radio displayed CALL on the screen and it cut out the music. I double checked that I was grounding pin 2 and not 3 which is for telephone and it was definitely pin 2. Connecting Pin 2 to Pin 6 is my next step. This may allow the radio to go to satellite mode.


With call on the screen it appears as though audio sent down pins 8 and 4 would probably play through the stereo. I will check this when I get time. I am still concerned with how left and right channels are derived from this jack.

Worst case scenario it may requiring soldering onto the volume controller where they do arrive as separate channels. Hopefully that can be avoided.

[rpm6500]

I don't know for sure as its a bit difficult to judge without a searchable PDF or the board in front of me but it looks as though its a simple filter setup near CN402. I think CN402.4 and CN402.8 are mono (P and N) inputs. Then filtered and split near CN402 before heading over to IC206.

Could these be for a phone kit install which would only have one channel?

I'm still looking but it seems that the sat switch will want a jumper between CN402.2 (through resistor to IC601.24) and CN402.6 (Digital GND) to begin working.

If I can help let me know. I'm by no means an DE but I'm not bad in my profesion as a PCB designer.

[rpm6500]

Well, it looks like I was half right.... just looked at the other thread... If I get time to check the schematics this afternoon I'll see if I can find the audio input for SAT radio.

Quote from Jon
Attached is the Audio wiring diagram for the 2005 Legacy. In that diagram, connector i85 corresponds to CN402, but the pins are numbered backwards. So,
i85 #1 = CN402 #4 (SIGNAL +)
i85 #2 = CN402 #3 (TEL ON)
i85 #3 = CN402 #2 (SATEL SW +)
i85 #4 = CN402 #1 (WOOFER +)
i85 #5 = CN402 #8 (SIGNAL -)
i85 #6 = CN402 #7 (WOOFER -)
i85 #7 = CN402 #6 (SATEL SW -)
i85 #8 = CN402 #5 (N.C)

The two SATEL SW pins connect to the remote (i.e. "satellite") audio switches on the steering wheel. The two WOOFER pins connect to the "Super Woofer" in the station wagon cargo area. And the N.C pin is connected for some reason to the Body Integrated Unit.

I suspect the remaining three unused pins (TEL ON, SIGNAL +, SIGNAL -) were designed to support a handsfree phone kit. Applying a voltage to the TEL ON pin would cause the headunit mute whatever it was playing and put the audio from SIGNAL +/- on the speakers. If you're content with mono sound, that'll get you AUX IN.

[zmarko]

I'm eagerly watching these threads. I don't understand all the 'pin' talk and whatnot, but if someone provided detailed pictures of what to do where (on the boards and stuff), I could pull it off.

:subscribe:

[2furious]

Clever...!!!

Subscribe..

[Andyjo]

Just check out IC 206 i believe, both Radio & CD signals come together there, so you could just tap the AUX in there, and trick the HU into muting the radio & cd at the same time, and you'd be golden, which looks like what you're doing... hmmm...
so wire up the sat button to the 'tel on' and blamo.... looks good to me! i'd do it if i brought my soldering iron back to school...
oh yeah, and the 'pin' talk... whenever you have a chip, or something on a PCB, it has 'pins' which are connected to the PCB... those pins are how the data/signals are transfered throughout the HU... just soldered joints really...

[mcwiggin]

Ok here is my game plan. Looks like the stuff about the satellite switch is true :-( The good news is bringing the unit into call mode is easy! Tapping in the audio in stereo isn't quite as simple but is totally doable.

Looks like I need to remove the resistors (this is pretty easy and can be done with a nail clipper) R251, R252, R351, R352 (doing this will untie the right and left channels from each other) the next step is to solder right ground to the upper pad for 252 and left ground to the upper pad of 352 then connect audio for the right to the upper pad of 251 and audio for the left to the upper pad of 351

http://www.mcwiggin.com/subaru/resistors.png

http://www.mcwiggin.com/subaru/audioplan.jpg


I will let you know how it goes... I may do it tonight or tomorrow depending on my schedule.

I will take pictures

[zcarmob]

Here is IC206 where the audio goes in. Pins 4 and 33 are inputs from the cd and radio. Pins 2,3,34,35 are coming from connector CN402 pins 4 and 8. Pin 6 on connector cn402 looks like a ground.

[kp1095]

Got an ipod and sat now i have to do this, just so it looks sanitary.

susbscribe.

maybe i could just send someone my stocker and exchange it for one already done!!!

for a fee of course.

K

[zcarmob]

mcwiggin,

While you are testing try this.

With and ipod or some other audio device.
Connect Right + to pin 4 on connector cn402.
Connect Left + to pin 8 on connector cn402.
Connect ground to pin 6 on connector cn402.

Now ground pin 2 and try to play the audio.

I was looking at the pc board and capacitor c402,c403,c404,c405 all have seperate. traces to resistors r251,r351,r352, and r252. So that means if you run the right side to one pin 4, left side to pin 8, and the negative ground to pin 6 then that should work.

The only problem i see is that both left and right will be mixed together, because pin 8 on cn402 connects to both pin 3 and 34 on ic206. Also pin 4 on cn402 connects to pins 2 and 35 on ic206.

[Andyjo]

So, in order to use the 'call' feature to grab a audio signal, you'd have to ground pin 6, on cn402, and pull the resistors, and dump in your audio signals, via pins 2,3,34&35?
If you were to just jump off the FM / CD and mute either of those units, you'd just have to tap into pin 4, and 33 on IC206..
i guess what i'm wondering is what's different between pins 2 & 3 and 34 & 35.. i see it says L+,L- and R+, R-
what does that really mean for connecting an audio connection there?
it seems to be that those resistors are there too... what drop down the signal?

[mcwiggin]

Because when moving to call mode it changes the input on the volume control chip. so adding audio where the FM + CD connect won't work. The call feature has its own volume / bal / fad / ect.... that are diffrent from the other modes... removing the resistors stops the audio from traveling back to where the 2 channels are linked together.

[mcwiggin]

Ok just looked at the Chip Diagram and looks like your suggestion may be a possibility... I will look into it..

Hopefully I will have time tomorrow to do some experimenting

[mcwiggin]

mcwiggin,

While you are testing try this.

With and ipod or some other audio device.
Connect Right + to pin 4 on connector cn402.
Connect Left + to pin 8 on connector cn402.
Connect ground to pin 6 on connector cn402.

Now ground pin 2 and try to play the audio.

I was looking at the pc board and capacitor c402,c403,c404,c405 all have seperate. traces to resistors r251,r351,r352, and r252. So that means if you run the right side to one pin 4, left side to pin 8, and the negative ground to pin 6 then that should work.

The only problem i see is that both left and right will be mixed together, because pin 8 on cn402 connects to both pin 3 and 34 on ic206. Also pin 4 on cn402 connects to pins 2 and 35 on ic206.

Tried the audio on CN402.... It does work. Its sounds good! It is mono :-(

hence working on these other mods.

[Deer Killer]

If someone gets a chance let me know what they think is going on with the left and right audio signals signals (C402 - C405 are 1uf caps)
Those are filters, so you don't need ground loop isolators, etc. Also they may filter out some audible frequencies since the input is for voice..

L/R is obvious tied together for mono input. However since this works you should be able to get stereo input by doing the following:

Cut the trace from c402 to c403 on the input side.

Cut the trace from c404 to c405 on the input side.

Now you should be able to tap in stereo audio to that side of the capacitors, however in order to have full filtering you will need two more inductors like L605 for the two new lines you have created, and add them in series to the input like how the two pins above are connected with them.

PS damn, now after I dropped all that cash on an 07 radio.. I don't give a crap about mp3 or srs..

[zcarmob]

Instead of cutting traces why not just unsolder one side of c403 and c405 to test then if it works just remove them all together.

Why would you need to add two more inductors since they are all ready there?

[Deer Killer]

Instead of cutting traces why not just unsolder one side of c403 and c405 to test then if it works just remove them all together.

Why would you need to add two more inductors since they are all ready there?
because you will have four wires. If those are smt caps, good luck...

[mcwiggin]

Ok here is my game plan. Looks like the stuff about the satellite switch is true :-( The good news is bringing the unit into call mode is easy! Tapping in the audio in stereo isn't quite as simple but is totally doable.

Looks like I need to remove the resistors (this is pretty easy and can be done with a nail clipper) R251, R252, R351, R352 (doing this will untie the right and left channels from each other) the next step is to solder right ground to the upper pad for 252 and left ground to the upper pad of 352 then connect audio for the right to the upper pad of 251 and audio for the left to the upper pad of 351

http://www.mcwiggin.com/subaru/resistors.png

http://www.mcwiggin.com/subaru/audioplan.jpg


I will let you know how it goes... I may do it tonight or tomorrow depending on my schedule.

I will take pictures

Just preformed this mod... The good news! Audio Works... Its in stereo.. The bad news... I think I need to add those resistors back as turning volume above 1% on my ipod leads to distortion. This is an easy fix. Other interesting things to note. While in call mode the stereo won't exit all mode regardless of the cars power state till you unground pin 2(3) the music stays on.. This makes sense. Like if you were on a call and turned your car off.

I will let you know how it goes with adding the resistors.

[zcarmob]

Now we have to figure out how to get the SAT switch to work or somehow ground pin 2.

But I think if you leave those resistors alone and remove those 2 capacitors it should work.

[Deer Killer]

you _need_ those resistors, you may have damaged the chip without them :O Theoretically you also need some sort of decoupling like that is going on in the official line-in.. i.e. those caps and inductors.

[mcwiggin]

Added the resistors and it sounds great..

[mcwiggin]

Right now I have the + of the op amps that the audio is feeding just danlging.. The resistors are on the - side of the op and feed the line in audio. It sounds good.

Made a really simple setup to switch the radio into call mode when I turn on my satellite radio using the output it provides for FM modulation. It runs 5v down this to trip the accessory which disconnects your stock antenna. I simply attached a resistor and to the +5v and then to the base of a transistor allowing it to connect the call to ground.. This could be done with a relay too.. but this was easier with what I have on hand.


I am having an issue though.. There is a hum in the background so somewhere noise is getting into the system. Its only audible when there is no audio playing but it is audible. Possibly adding back the capacitors will filter out this noise. The other issue is I am sure I am doing the wrong thing with how the audio is fed to the volume chip... If someone could guide me as to what is the right thing to do that would be great.

[CasopoliS]

waaay over my head but I am impressed

[mcwiggin]

Don't worry... once I get it right.. I will write down some simple instructions.. in the mean time... its going to be lots of electronic gobbldy gook.

[zcarmob]

Right now I have the + of the op amps that the audio is feeding just danlging.. The resistors are on the - side of the op and feed the line in audio. It sounds good.

Made a really simple setup to switch the radio into call mode when I turn on my satellite radio using the output it provides for FM modulation. It runs 5v down this to trip the accessory which disconnects your stock antenna. I simply attached a resistor and to the +5v and then to the base of a transistor allowing it to connect the call to ground.. This could be done with a relay too.. but this was easier with what I have on hand.


I am having an issue though.. There is a hum in the background so somewhere noise is getting into the system. Its only audible when there is no audio playing but it is audible. Possibly adding back the capacitors will filter out this noise. The other issue is I am sure I am doing the wrong thing with how the audio is fed to the volume chip... If someone could guide me as to what is the right thing to do that would be great.

What is the problem you are having with the volume?? The volume should work with the way you have it hooked up.

[Deer Killer]

if you don't match the impedances and use filters as designed, you risk letting the magic smoke out. And electronics don't work after the magic smoke leaves.

[mcwiggin]

Update:

Ok- Added the resistors. Everything works as expected. Its pretty slick. I turn on my sirius receiver and the head unit goes into call mode and tunes start playing. Turn off the sirius receiver and the head unit goes back to whatever state it was in before.

I have one remaining issue.. There is still a whine in the system. I did something wrong in finding a suitable audio ground. Using the stereo body as a ground turned out not be a clean enough ground for audio use. I need to figure out where I can find a clean ground so that I can eliminate the engine whine.

Besides that.. I am pretty excited. The sound is clear and clean as would be expected.

If anyone has ideas where I can find a suitable audio ground (hopefully w/o disassembling the whole head unit again) please let me know.

[jazzymt]

You're gunna need a ground loop interupt... Seriously - there is simply no other way to avoid that noise if your audio source causes it...I've seen people try everything & a GLI is all that ever worked.

Nice work btw.

[Deer Killer]

Update:

Ok- Added the resistors. Everything works as expected. Its pretty slick. I turn on my sirius receiver and the head unit goes into call mode and tunes start playing. Turn off the sirius receiver and the head unit goes back to whatever state it was in before.

I have one remaining issue.. There is still a whine in the system. I did something wrong in finding a suitable audio ground. Using the stereo body as a ground turned out not be a clean enough ground for audio use. I need to figure out where I can find a clean ground so that I can eliminate the engine whine.

Besides that.. I am pretty excited. The sound is clear and clean as would be expected.

If anyone has ideas where I can find a suitable audio ground (hopefully w/o disassembling the whole head unit again) please let me know.

The right way to do it is the use the ground pins above the pins above the pins you tapped into. GLI or not if you're attaching your audio device's output to body ground on one side it's going to be noisy.. Also you're going to be missing bass as the actual audio ground is floating. What I suggested above is "sorta" what you're doing but using the on-board filtering..

[mcwiggin]

Which pins are you referring to as the ground pins? Audio is not my specailty when it comes to electronics. I am much more at home with digital logic circuits. Luckily there you can do some pretty nasty things and still get away with it because you just need to get the 1 or 0 across..

[Deer Killer]

as labelled R- and L-

[mcwiggin]

I tried grounding to those pins but the audio went away all together. I am doing something wrong. If you look at the block diagram of the volume chip the + and - are both inputs to an op amp inside the chip. I am actually running the audio through the - lines right now. I know I have done something wrong but I am not sure what the right way is to connect the audio.

http://www.mcwiggin.com/subaru/VolChip.png

[Deer Killer]

Don't ground those pins! None of the input audio connectors should be grounded to body either.

The only thing grounded should be the logic select, if you're using that.

Just use R+/R- and L+/L- as your two channels. Tie L- and R- together if you're using something with a common audio -, like a headphone output jack.

[drcaveman]

Great I am glad to see such progress, way beyond my Mechanical Engineering knowledge.

DrCaveman

[Jon [in CT]]

It seems like there are many lumps in the circuit between CN402 and IC206:

http://www.mcwiggin.com/subaru/SatInput.png

http://www.mcwiggin.com/subaru/audioplan.jpg

You're trying to ignore as many as possible. Maybe that isn't a good idea. Maybe, instead, you need an Aux Box with circuits that duplicate what the headunit does to the handsfree phone audio input between its arrival at the connector and its input into IC206.

The Aux Box circuits would look like this:

http://i16.tinypic.com/2wogn01.jpg

The only problem is that the service manual never provides the inductance value for the coils. Maybe you could measure it and let us know what it is.

[zcarmob]

Can't you just connect the R+ to pin 4 of CN402 and the L+ to pin 8 of cn402.
Then connect the R- and L- to pin 6 on cn402.
With those connected then remove c403 and c405 capacitors.
That should work right?
The Radio/CD does not have a negative into IC206.

[Deer Killer]

;948751']
The only problem is that the service manual never provides the inductance value for the coils. Maybe you could measure it and let us know what it is.Well, theoretically it's "ok" to skip that, it's a low-pass filter anyway. The cap is much more important as it at least provides some de-coupling from the input..

[zcarmob]

Anyone think my suggestion in post #37 will work?

[Jon [in CT]]

Anyone think my suggestion in post #37 will work?It won't work.

[zcarmob]

Any reason why it wouldn't???

[NutBucket]

It won't work because pins 8 and 4 represent Signal + and Signal - of a mono circuit. You can't feed Signal + into both sides of an amplifier.

[NutBucket]

Ok, upon some further consulting there is a bit of misinformation floating around here. If you notice on IC, the signals into the pins of interest are labeled L+ and L-. If I'd paid attention I would have immediately identified them as differential signals. So, what zcarmob posted in #37 works, sort of. You see, L+ and R+ are tied together. You'd still lose stereo. What you need to do is tie one input from CN402 to R+ and the other to L+. Then, ground both L- and R- to signal grougn. Tie the signal ground from the auxiliary source to that same signal ground in the radio. Now we've effectively converted the differential input to a single ended one. A bit crude, but we're talking about audio signals here. By doing this, we eliminate the need for any sort of auxiliary adapter and noise filters. We'll just use what's already provided.

And we were wondering what value L606/L605 were? Well, they're not really inductors per se. They're beads, or EMI filters to help prevent any sort of alternator whine and what not. They are not filters designed to isolate vocal frequencies.

I plan on trying this sometime this week when I have some time at work.

Any thoughts?

[zcarmob]

Pins 2 and 3 of IC206 are for Right + and -.
Pins 35 and 34 of IC206 are for Left + and -.

On cn402 pin 4 and 8 go to 2 capacitors each then they split into R+, L+ and L-, R-. All have seperate traces to IC206.

Pins 2 and 3 are connected to the same transistor in the chip also Pins 34 ansd 35 are connected the same way.

if you remove c403 and c405 capacitors. then you will only Right + going to pin 2 and Left + going to pin 34. you could jump it over to pin 35 so both go to the Positive pin on IC206. The negative Left and Right will be taken care of with hooking it to ground.

Then if you ground pin 2 on CN402 then that will put the radio in call mode and sound should come through the speakers in stereo.

[NutBucket]

Sounds about right to me. Time to get soldering;)

[zcarmob]

you mean desoldering

[zcarmob]

The trigger is to ground pin 2 on cn402

[NutBucket]

Well, both. Gotta remove then jump;)

[Deer Killer]

Ok, upon some further consulting there is a bit of misinformation floating around here. If you notice on IC, the signals into the pins of interest are labeled L+ and L-. If I'd paid attention I would have immediately identified them as differential signals. So, what zcarmob posted in #37 works, sort of. You see, L+ and R+ are tied together. You'd still lose stereo. What you need to do is tie one input from CN402 to R+ and the other to L+. Then, ground both L- and R- to signal grougn. Tie the signal ground from the auxiliary source to that same signal ground in the radio. Now we've effectively converted the differential input to a single ended one. A bit crude, but we're talking about audio signals here. By doing this, we eliminate the need for any sort of auxiliary adapter and noise filters. We'll just use what's already provided.
That's what I said 9 posts ago.. Also tying the L- and R- does not make it into a non-differential signal!! The ground still floats.


And we were wondering what value L606/L605 were? Well, they're not really inductors per se. They're beads, or EMI filters to help prevent any sort of alternator whine and what not. They are not filters designed to isolate vocal frequencies. Inductors are inductors. The filter frequency depends on the impedance of the circuit, which I cannot guess at. EMI filters don't filter magic EMI signals, it's all electricity and magnetism...

[NutBucket]

You're right, tying L- and R- doesn't make it non-diff. Tying it to signal ground just means we can use the diff input with a single-ended source, like you said. I didn't read fully either;)

From what I could find online, I found a very similar part number for a Murata part that is an EMI filter in the form of a SMT chip....unless I'm not remembering right from earlier in the day. I'll have to look it up again tomorrow since I think I left the datasheet open on one of the computers at work.

[NutBucket]

Well, I bring some interesting news on this project. I did the mod on the caps, C402-405. Without having yet put the unit back in the car (still at work), I can tell you that the audio definitely comes through. Now for some quirks. When in call mode, you cannot adjust treble, bass, mid, fader or balance. Also, when you go into call mode, the volume defaults to 16 (but you can adjust it).

I figure I can use the iPod to adjust the tone....hopefully it doesn't fade to front by default. Will report back later. I did take some pics of the mods I made; I'll post them tomorrow if it turns out this is a worthwhile mod.

[NutBucket]

Ok, got home, found my adapter cable and test. Using the headphone jack the volume in "call" set to 16 is about the same setting 10 on radio/cd. Also, it appears that the fader is set full front; I didn't hear anything out of the rears. It does not appear that the tone settings are adjusted to emphasize voices, which is good news.

Not sure what can be done about the fader but I suspect the volume issue can be fixed if it really bothers anyone. It should be noted that the radio/cd volume is separate from "call" volume; so if you're listening at FM 10, switch to call and then go back to FM, the FM volume will still be 10.

So is this better than Jazzy's solution? That's for you to decide.

[NutBucket]

Ok, here are the pics. First one is stock, second one modded.

#1
http://i7.photobucket.com/albums/y263/Drm2Ski/Misc/DSCN4952.jpg

#2
http://i7.photobucket.com/albums/y263/Drm2Ski/Misc/DSCN4954.jpg

The gray wire I used as ground. I connected left and right directly to pins 4 and 8 of CN402. I then ran a separate pair of leads to enable call mode. Nothing is mounted yet as I'm still deciding whether I want to stick with this method or not.

[zcarmob]

Mcwiggin was your setup playing through all the speakers or was it just playing through the fronts?

[SVXdc]

Great work, guys!

When in call mode, you cannot adjust treble, bass, mid, fader or balance. Also, when you go into call mode, the volume defaults to 16 (but you can adjust it).As I started reading this thread I was afraid it would do something like this.

Can you tell if the HU is leaving the bass, mid, and treble where they were prior to "call" mode, or is it changing them to some "medium" values, like what it's doing with the volume? (you could test by setting each one all the way up or down prior to switching into "call" mode)

... it appears that the fader is set full front; I didn't hear anything out of the rears. ...This is almost certainly being controlled by software in the HU's microprocessor, so fixing this would require more hacking than it's worth.

[gtwannabe]

Anybody look into disabling the loudness contour on this radio? BTW it is possable to tap the output from the volume IC and use it as a line output to an external amp. I have done this just need to get rid of the loudness crap.

[SVXdc]

To the folks who played with this: Did any of you try grounding the "Tel On" (enable) pin while the HU was powered off?

I've been thinking about what it would take to use this input with an actual phone kit such as a Parrot.

I'm curious if the Tel On pin "wakes up" the head unit so it will still send the audio to the front speakers. Otherwise you would need to make sure you turn on the HU before being able to place or receive calls using the phone kit.

If the pin does power on the HU, does it power back off after you unground the pin? I would expect it should.

And if it does work, is it only while the ignition is in the "Accessory" or "On" positions, or does it also work with the key off?

Also: When you adjust the volume during "Call" mode, go back to normal music mode, then get another call, does it remember the "Call" volume you set previously?

[NutBucket]

I'm not sure if it "wakes" the HU. However, I do know that "call" is on the display even if the radio is off and the hu remains off when you un-ground the pin. So the short answer is, probably;) I don't recall whether it works when the car is off. I want to say no but don't quote me on that.

If I used my phone in the car more I'd probably be working on the same project;)

[SVXdc]

If the HU is displaying "Call" then I have no doubt it's firing up the amp, which is all I really mean by "wake up." So that means a phone kit will work even when you haven't powered on the HU.

I'll bet it doesn't work with the key off, since nearly everything else in the car is that way.


How about the "Call" mode volume setting -- is that remembered between calls?

[NutBucket]

Yes, it defaults to 16.