Hello,
I just got a Renault Laguna 2. It has the factory head unit, it says "Tuner List" on it's front. Nothing fancy, CD-Player and AM/FM radio, with an optional CD-Changer (that it also has in the car, but is missing the CD storage device, has only the player).
I really like the way it is integrated with the car, I have the remote on the steering column, also uses the HUD of the car for info.
I'm not a fan of the Christmas lights like aftermarket players but I do need an aux input into this unit.
The only option that this unit provides is the input from the CD changer, but that is spdif based, and also has some serial data RX/TX happening between the units. And that would seem like the long way to hack, also I need something that can take digital sound from my phone and convert it to spdif etc. Too much trouble.
The easy way for me looked like I could just hack another input into the dsp chip.
Looking at it's schematic, the chip has many inputs. The only problem is that the unit does not go through all of the inputs. If no CD is inside the unit, it defaults to radio, and I can only switch between AM/FM. The CD unit inside this player also uses a spdif input on the dsp chip. So no luck there. I would have happily removed the cd-unit but no luck.
So because the unit talks to the cd-player or cd changer via serial to determine what's happnening, I can only use the two active inputs that are available always. AM and FM radio. I need FM but I don't need AM. So looking at the schematic, I noticed that AM audio signal goes into one pin, the Right Channel/Mono pin. The left channel is floating and is conveniently broke out into a small test pad.
I decided to make a test, and inject another signal on that pin. That way I figured that the DSP detects signal on that pin and starts a stereo output. But sadly that isn't the case. I couldn't get my test signal on either channel.
What else should I do? Is there something that sets the DSP on mono/stereo for AM input?
If my test worked, I could have cut the trace leading to the AM input pin and then inject left/right signal with a plain cable that would go out of the unit to my phone.
Any ideas?
On the picture, I circled with red the left channel (not connected one) and with yellow the active right/mono channel.
Is there another radio signal that tells something to the DSP about mono/stereo? If so, is that signal on the same line with the FM data? I see a line named Level, what does that do?
edit: I had a look on the other side of the board, it's two layers and those are not vias, they are indeed pads, or test pads or whatever. They are not going on the other side, so the Left channel AM input is indeed floating. Along with the other inputs.
I just got a Renault Laguna 2. It has the factory head unit, it says "Tuner List" on it's front. Nothing fancy, CD-Player and AM/FM radio, with an optional CD-Changer (that it also has in the car, but is missing the CD storage device, has only the player).
I really like the way it is integrated with the car, I have the remote on the steering column, also uses the HUD of the car for info.
I'm not a fan of the Christmas lights like aftermarket players but I do need an aux input into this unit.
The only option that this unit provides is the input from the CD changer, but that is spdif based, and also has some serial data RX/TX happening between the units. And that would seem like the long way to hack, also I need something that can take digital sound from my phone and convert it to spdif etc. Too much trouble.
The easy way for me looked like I could just hack another input into the dsp chip.
Looking at it's schematic, the chip has many inputs. The only problem is that the unit does not go through all of the inputs. If no CD is inside the unit, it defaults to radio, and I can only switch between AM/FM. The CD unit inside this player also uses a spdif input on the dsp chip. So no luck there. I would have happily removed the cd-unit but no luck.
So because the unit talks to the cd-player or cd changer via serial to determine what's happnening, I can only use the two active inputs that are available always. AM and FM radio. I need FM but I don't need AM. So looking at the schematic, I noticed that AM audio signal goes into one pin, the Right Channel/Mono pin. The left channel is floating and is conveniently broke out into a small test pad.
I decided to make a test, and inject another signal on that pin. That way I figured that the DSP detects signal on that pin and starts a stereo output. But sadly that isn't the case. I couldn't get my test signal on either channel.
What else should I do? Is there something that sets the DSP on mono/stereo for AM input?
If my test worked, I could have cut the trace leading to the AM input pin and then inject left/right signal with a plain cable that would go out of the unit to my phone.
Any ideas?
On the picture, I circled with red the left channel (not connected one) and with yellow the active right/mono channel.
Is there another radio signal that tells something to the DSP about mono/stereo? If so, is that signal on the same line with the FM data? I see a line named Level, what does that do?
edit: I had a look on the other side of the board, it's two layers and those are not vias, they are indeed pads, or test pads or whatever. They are not going on the other side, so the Left channel AM input is indeed floating. Along with the other inputs.
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I just saw in the chip datasheet that the mono/stereo is controlled by IC, so no way of activating that.
I was also thinking of replacing the amplifying chip to something better (tda7850 from tda7385) but the heatsink is really small.
I need to rethink this.
What bugs me is that a different head unit would kill my remote controls and dash display.
There are adaptors for the controls, and they are around 30$, there are also adapters for the display, but those are 130$.
I was also thinking of replacing the amplifying chip to something better (tda7850 from tda7385) but the heatsink is really small.
I need to rethink this.
What bugs me is that a different head unit would kill my remote controls and dash display.
There are adaptors for the controls, and they are around 30$, there are also adapters for the display, but those are 130$.
There is nothing to be destroyed. Maybe the filtering inductor? But let's calculate:
TDA7385 is a 4x23W device at 14.4V (at 10% distortion, that's at max, and I wouldn't listen at that volume). So that translates into 4x1.6A = 6.4A.
TDA7850 is a 4x30W device at 14.4V (same 10% distortion) That is 4x2.1A=8.4A. At max volume with the more powerful chip I would have a total extra increase of 2A, that is continuous. I guess the inductor can handle it, especially as I'm not going to max it.
But yes, I have considered the other option, of adding another amplifier. Just tap the chip inputs and route that to another 4in/4out amplifier. I still need to figure how to inject stereo signal, as FM even if it's stereo, the dsp chip does the decoding (RDS/MPX lines input the chip).
The modulator is not a viable solution, I've used them before and they are total crap. On bass I'd get bells instead.
edit: Forgot to add the schematic
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Me neither, and I've tried several.
Seems like there's this guy that hacked the FM part. And used a switch between the AUX input signal and FM so he can have both.
https://docs.google.com/document/d/1k6icso8EXXboqhhw6rfewVOAxOPuBIrdoGTy3NO4hiE/edit?pli=1
Basically he's tapping on the FM MPX line and encodes his aux signal to be decoded back by the dsp. Lots of work.
Having a CDC option, and not using it, I figured I might go that route. There is some info on this on the Renault forums. I may update if I make some progress for the AUX input.
On the amplifying part, I will first try to replace that chip and see if it's any better and if I have any trouble with extra heat, or I may just use an external one.
First, I need to find a way to inject my signal into this unit, then I decide how I will amplify.
Seems like there's this guy that hacked the FM part. And used a switch between the AUX input signal and FM so he can have both.
https://docs.google.com/document/d/1k6icso8EXXboqhhw6rfewVOAxOPuBIrdoGTy3NO4hiE/edit?pli=1
Basically he's tapping on the FM MPX line and encodes his aux signal to be decoded back by the dsp. Lots of work.
Having a CDC option, and not using it, I figured I might go that route. There is some info on this on the Renault forums. I may update if I make some progress for the AUX input.
On the amplifying part, I will first try to replace that chip and see if it's any better and if I have any trouble with extra heat, or I may just use an external one.
First, I need to find a way to inject my signal into this unit, then I decide how I will amplify.
The more powerful amplifier has better distortion figures:
Stock TDA7385
http://www.st.com/web/en/resource/technical/document/datasheet/CD00002618.pdf
TDA7850
http://www.st.com/web/en/resource/technical/document/datasheet/CD00145702.pdf
I don't know if I'm going to do this. I'm currently in a standstill as whatever I do, I can't seem to have it all.
The HU that came with the car, talks on i2c with the HUD. But this unit does not have AUX. There's another unit, that has AUX input, talks to the steering column commands, but talks with the HUD via CAN. And this unit also has a beefier heatsink (and chip I presume).
Going for an aftermarket one I loose both controls and HUD unless I buy really expensive adaptors.
Then there's the option where I can cut the spdif signal from the CD part of the HU, install a switch, and inject in that my aux signal. Seems like the easiest option, I keep the controls and HUD, but I need to do an extra AD conversion (adds cost and probably quality loss).
Stock TDA7385
http://www.st.com/web/en/resource/technical/document/datasheet/CD00002618.pdf
TDA7850
http://www.st.com/web/en/resource/technical/document/datasheet/CD00145702.pdf
I don't know if I'm going to do this. I'm currently in a standstill as whatever I do, I can't seem to have it all.
The HU that came with the car, talks on i2c with the HUD. But this unit does not have AUX. There's another unit, that has AUX input, talks to the steering column commands, but talks with the HUD via CAN. And this unit also has a beefier heatsink (and chip I presume).
Going for an aftermarket one I loose both controls and HUD unless I buy really expensive adaptors.
Then there's the option where I can cut the spdif signal from the CD part of the HU, install a switch, and inject in that my aux signal. Seems like the easiest option, I keep the controls and HUD, but I need to do an extra AD conversion (adds cost and probably quality loss).
Does anyone know if Sony's car stereos use the same remote protocol for the jack connection on the back? There's a blue ring around that jack connection.
I see a newer model also has the same jack, and I know there's an adapter for my car from Sony that allows the use of both the steering column controls + auxiliary HUD of the car. But that appeared some time ago, I don't know if they kept the same interface.
I'm thinking of this Sony DSX-A40Ui unit. Seems to do what I need, radio/aux, it misses the cd-player and I'm very ok with that, plus it has a line level output. That way I could use the unit as a control unit, and add my amplifier for the speakers, and still use the car's controls/HUD. And if need be, it has the standard 4x whatever watts they can actually produce with 14.4V feed. Until I get a proper amplifier.
I see a newer model also has the same jack, and I know there's an adapter for my car from Sony that allows the use of both the steering column controls + auxiliary HUD of the car. But that appeared some time ago, I don't know if they kept the same interface.
I'm thinking of this Sony DSX-A40Ui unit. Seems to do what I need, radio/aux, it misses the cd-player and I'm very ok with that, plus it has a line level output. That way I could use the unit as a control unit, and add my amplifier for the speakers, and still use the car's controls/HUD. And if need be, it has the standard 4x whatever watts they can actually produce with 14.4V feed. Until I get a proper amplifier.
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