Aux input on CDM / receiver?
 

It looks like there are a few car radio repair businesses that offer the service of adding a 3.5 mm auxiliary input jack to the Bose CDM / receiver box. Has anyone here had this done?

I'm very comfortable with a soldering iron (and doing thru-hole rework if necessary), so I'd prefer to make this modification myself to save some money and learn something in the process. If anyone has photos, a schematic, or a description of the changes required, that would be very helpful.

At this point, I'm really only interested in adding the aux input at the CDM, not at the head unit.

--Colin

Re: Aux input on CDM / receiver?
 

I have only ever seen it done to the head Unit in the Cassette area. corvetteforum.com has a radio section I suggest you look in there as well but it spans ALL generations.


http://www.corvetteforum.com/forums/...lectronics-20/

Re: Aux input on CDM / receiver?
 

I'll give that a try. I did find a few threads over there that had been started and abandoned without much information being posted.

For reference, here's the setup that I had in mind:

http://i39.tinypic.com/28bb6me.jpg

Re: Aux input on CDM / receiver?
 

http://i529.photobucket.com/albums/d...psbmknfmfs.jpg

http://i529.photobucket.com/albums/d...pshxpsrdfr.jpg

Schrade is the Electronics Mod Guru

http://www.zr1.net/forum/showthread....light=bose+aux

I believe Marc Haibeck also offers this mod

http://www.zr1specialist.com/

Re: Aux input on CDM / receiver?
 

It would be neat if the AUX in didn't require a CD to be playing the whole time. I did that in my Jeep and now that the changer is going out it no longer works.

Why was Schrade's post deleted?

Re: Aux input on CDM / receiver?
 

I always had in the back of my wish list to do this mod too, any chance we can get a refresh on the post? My CD player is dead and I'd love to hook up an old MP3 player in the glove box.

Re: Aux input on CDM / receiver?
 

I sent my head unit to Dr. Don and he put the aux input on the end of a long wire and I have it in my center console glove box. Will be connecting a small XM radio to it shortly. I like it because everything looks stock.

Re: Aux input on CDM / receiver?
 

With Dr. Don's mod do you still have to have a CD spinning or a tape in the deck?

Re: Aux input on CDM / receiver?
 

Schrade did it and provided a partial schematic and pics of where the wiring goes.

Re: Aux input on CDM / receiver?
 

There is a power button that you press to activate the aux input and I believe it is off the tape connection but no tape has to be in the unit. Best for you to call Dr. Don at 936-435-1811 and he will explain it all to you. He is a great guy and takes the time to explain everything.

Re: Aux input on CDM / receiver?
 

For my set-up,
it's a CD that has to be inserted.

Re: Aux input on CDM / receiver?
 

Now I like this idea. If only someone could do it for less than $200 that would be awesome.

Re: Aux input on CDM / receiver?
 

Pretty sure Doctor Dons price is around 100.00.

Re: Aux input on CDM / receiver?
 

You are correct. It is only $100. I will be sending my headunit in soon.

Re: Aux input on CDM / receiver?
 

You can't go wrong with him. He's a great guy to do business with.

Re: Aux input on CDM / receiver?
 

Dr Don's does great work. Ilike that idea as well as the drive belt for the CD rom is not getting a lot of run time.

Re: Aux input on CDM / receiver?
 

Here's my CDM, with an aux input installed by Factory Car Stereo Repair of Longwood, FL. I would have preferred to just do the work myself since it uses about two dollars worth of parts and cost $100 (plus shipping), but I couldn't find good schematics/drawings of the CDM CCA.

This works by using a switched 3.5mm phono jack with a normally-closed switch on each channel. Both switches open when a plug is inserted, and the audio is then taken from this input rather than from the head unit. This does not require that a tape or CD be inserted.

It would be nice if someone who has access to schematics could identify the contact points in the photos, and post component names or other information that would make it easier for others to do this modification.

This is for a late 1995 car. I don't know if there are changes in the CDM board layout that would change the wiring.

White: Left channel signal (3.5mm tip)
Green: Left channel NC switch - opens when plug is inserted
Black: Right channel signal (3.5mm ring)
Red: Right channel NC switch - opens when plug is inserted
Clear: GND (3.5mm sleeve)

For the switched jack, you can use Switchcraft part no. 35RAPC4BH3, available via Mouser and other places for less than $1.50.

EDIT: 98indypacer pointed out to me that it looks like the two traces between the white/green and black/red wires have been cut. That makes sense. When nothing's plugged into the jack, the switches are closed and those cut traces are bridged via the cable. When there's a device plugged in, the switches open and the downstream side of the signal path is being fed from the 3.5mm jack.

Higher resolution copies of the photos are hosted here:
http://i.imgur.com/kdhzeAT.jpg
http://i.imgur.com/IZGGubm.jpg
http://i.imgur.com/Q92ZzK4.jpg
http://i.imgur.com/K9a2yuY.jpg
http://i.imgur.com/8I6uXxn.jpg

--Colin

Re: Aux input on CDM / receiver?
 

Colin, how does it sound?

I contacted the same company and they said they would only install the input mod if they also serviced the CDM. He quoted $100 for the input mode and $120 for the CDM service. The total would be $220 plus shipping. When did you get your CDM modified? Did they require you have to have both services done?

Re: Aux input on CDM / receiver?
 

I'm reserving judgment on the sound quality because I seem to have one or more bad amplifiers (which seem to affect basically everyone with this Bose system sooner or later.) I'm getting some hiss/static from the rear; not sure yet if it's both sides. Hopefully this isn't a problem introduced by the CDM modification. If I do need one or two amps, maybe I'll check the For Sale section to see if anyone has a stock of the Nissan/Infiniti units.

I was able to get the aux input addition by itself, without any additional CDM service. This was just last Friday (March 20) that they did the work and shipped it out. The guy I spoke to on the phone made it a point to mention that they inspected my CDM for any issues, and that it seemed to be in exceptionally good condition. Maybe they would have required the additional service if they found any corrosion or failed components? Not sure.

Re: Aux input on CDM / receiver?
 

Interesting how I got a different story from the same company. I guess it depends on who you talk to about getting a quote to do the work.

Let us know when you get the amps sorted out.

Re: Aux input on CDM / receiver?
 

I determined that the hiss/static is coming from all four speakers, so either the amps are working fine or they're all degraded in a very similar way. The static is always a constant low volume, it's present whenever the stereo is on (regardless of whether I'm playing the radio, CD, or aux in), and it's unaffected by the volume, balance, or equalizer controls. Fortunately, it's such a low volume noise that I doubt I could even notice it with the engine running or with music playing.

I'm thinking that this CDM aux input mod must not have caused this problem. Since the aux audio seems to be injected downstream of the signal from the head unit (i.e. the head unit audio is switched out and the aux jack is switched in), I would expect the nature of the static to change when switching between the two if it were caused by this modification. Since it doesn't change, it seems like this caused by something else...

Fortunately, the quality of the audio from aux input is quite good -- basically indistinguishable from CD audio from the head unit.

EDIT: I added a note about the cut traces in my post with the photos of the mod.

Re: Aux input on CDM / receiver?
 

The audio is inserted at the last point before the preamp in the CDM so if the noise was a result of the mod it would be evident regardless of the input. It's possible that the noise is from the modification or you may have some issues on the CDM board. Might need to replace the electrolytic capacitors in the CDM if it really bothers you.