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something fishy 10-03-2004 12:39 AM

Make a line/aux in for your 2003 Bose headunit Ė step by step guide
Iíve been trying to find an acceptable way to hook an MP3 jukebox into my 350Zís Bose headunit.

Tape adapters and FM modulators didnít cut it. But it can be done, all you need is a healthy disrespect for your warranty.

The cassette deck in the Bose is separate module in the headunit that connects to the main PCB using a single row plug. The PCB on the cassette module helpfully has each pinís use stencilled on it. By breaking the left and right channel signal traces and the audio ground trace out of the cassette module before they go into the main PCB you can tap into these traces and make yourself a line in.

You will need:
The Philips and flat screwdrivers needed to remove the centre dash panel as per the instructions in the FAQ

A sharp knife or jewellers screwdriver (to break the PCB traces)

A stereo phono lead to make your line out with


Point nosed soldering iron and solder, plus I found corrosive flux a great help
(you canít use a heat gun but the soldering iron doesnít need to be ultrafine. The soldering needed is easier than involved in making up a set of audio leads).

This mod sacrifices the cassette function of the Bose, so if you use cassettes sorry this isnít for you. It goes without saying that your warranty is toast.

something fishy 10-03-2004 12:42 AM

1. Remove the dash and take the head unit out of it.
1. Remove the dash and take the head unit out of it.
The guide here: is excellent (thanks

something fishy 10-03-2004 12:43 AM

2. Remove the front (plastic) panel of the headunit.
2. Remove the front (plastic) panel of the headunit.

It is held on by little clips all around perimeter. You can see two of them in this shot which was taken when I was testing to see if it worked. There are two on each side and three at the top and bottom. Slide a small screwdriver in between the plastic and the metal, gently lever the plastic up from the clip and slide a thin piece of card between the two to allow you to tackle the next one.

All clips done the front panel and the PCB that holds all the front panel controls should come off without much force (if you have to force it, some of the clips arenít loose)

something fishy 10-03-2004 12:46 AM

3. Remove the (perforated) bottom of the head unit.
3. Remove the (perforated) bottom of the head unit.

It is held on by four small Philips screws through the bottom panel, two screws through the back and two screws through the front. All these removed carefully lever the bottom panel off at each side (at the join line) it will take a little force as there are some friction clips built into the side and (I think) the front.

something fishy 10-03-2004 12:47 AM

4. Remove the cassette unit.
4. Remove the cassette unit.

The cassette unit is now sitting right in front of you. This picture was taken while I was reassembling the head unit but shows where the four screws that hold the cassette unit in are (theyíre removed in this picture). To take the cassette unit out just remove these four screws and lift the unit vertically upwards.

something fishy 10-03-2004 12:48 AM

5. Find the correct PCB traces and break them.
5. Find the correct PCB traces and break them.

If you cassette unit looks like mine the back will look like this. The part sticking up (with 97-794-Y00 written on it) is the connector that plugs into the main PCB.

This picture shows how helpfully the PCB identifies what trace carries what signal. We need to break the traces for the Left (L-CH) and Right Channels (R-CH) plus the Audio ground (A-GND) upstream of the solder blobs (we will use those blobs to attach a cable to). You can break the traces by just scraping through them with the tip of a knife or some other sharp object (a jewellers screwdriver is ideal). You can see where Iíve done this in this closeup (note that I was a bit careless and let the knife slip a little).

something fishy 10-03-2004 12:49 AM

6. Attach a line out lead to the cassette unit PCB.
6. Attach a line out lead to the cassette unit PCB.

I just used a cheapo phono patch cord and cut one end off it. Carefully strip the cable. Wind the braided sleeves from the left and right channels together and tin them with a soldering iron. Strip the insulation off the left and right signal leads and tin those also.

It is easier to keep the leads about one inch long at this stage. You can cut them to the correct length now (for the A-GND lead) or after youíve soldered them in position (for the L-CH and R-CH signal leads). It is very easy to attach the leads to the solder blobs on the cassette unit PCB as long as youíve tinned them properly and everything is clean (I find a tiny amount of plumbers/corrosive flux aka soldering paste helps but you must clean any residue off the PCB when youíve finished)

Here is a picture of the cassette unit with the line out attached.

something fishy 10-03-2004 12:51 AM

7. Threading the cable out the back of the headunit
7. Threading the cable out the back of the headunit

If you used a cheapo patch lead like me the plugs should be small enough to feed through the various holes in the metalwork. If you used some nice shiny audiophile leads with big plugs my apologies because I should have warned you to feed the cable through first before you soldered it in place.

There is a metal bulkhead just behind the cassette unit This has a suitable hole on one side. You can see the cable fed through it here (this picture is taken with the satellite board that contains the Nav interface removed for ease of access. It is attached with two screws at the back, youíve already removed the right hand one to get the bottom off).

And there is a hole in the back of my headunit covered by a sticky black plastic patch. Peel that off and feed the lead through it. Before you do it might be a good idea to put sort of strain relief in. I did this by just loosely knotting the cable just before it exits the case.

something fishy 10-03-2004 12:52 AM

8. Reassemble everything
8. Reassemble everything

In the reverse order that you took it out; so:
Fasten the cassette unit back with the four screws
If you removed it put the Nav daughterboard back but donít screw it in until youíve put the bottom back on
Push the bottom plate back on and insert all screws (at this point fasten the Nav daughterboard back)
Carefully push the front panel back into place. It shouldnít take much force and should make a nice click when itís back in position.

You should now have something that looks like this:

something fishy 10-03-2004 12:53 AM

9. Testing and use
9. Testing and use

It is probably worth testing that it works before reassembling the dash. I didnít have a wiring loom for the Bose outside of the 350Z so I just plugged it in and connected the phono leads to a portable iRiver MP3 player. Here is a picture.

Pressing ďTapeĒ should now activate the line in. But you will need to fool the Bose into thinking that it is playing a tape (or nothing will happen). To do this I simply used a cassette adapter (one of the ones whose sound quality was so bad) with the input lead cut off (the picture is taken before the lead was given the chop, itís not connected).

It worked perfectly with much better sound quality than either a tape adapter (whose signal has to pass through two tape heads a few amplifier stages and some equalisation to get it to the point where youíve soldered the leads) or an FM modulator (I tried two, they were both lousy).

I was worried that the input would be very easy to clip and wouldnít be able to handle line level signals. A definitive judgement will await the arrival of my OmniFi DMP1 MP3 jukebox, but in the test with the iRiver (which is an iPod clone) I wasnít able to detect any obvious clipping even with the iRiver at very high volumes (at which point the line in was much louder than either radio or CD) so it seems to be useable.

something fishy 10-03-2004 12:55 AM

10. Caveats/warnings
10. Caveats/warnings

This seems to work for me; I donít use cassette at all so sacrificing it was an easy choice to make. It is pretty easy process (actually getting the dash off was harder) but breaking the PCB traces probably isnít easily reversible, so be careful. I donít know what will happen if you cut any of the other traces.

This was done on a 2003 350Z in Singapore Ė if your Bose headunit is substantially different from the pictures or doesnít have the helpful labels on each trace or you donít feel comfortable taking it apart you might want to think about some other route.

Hope that this helps some people.



Kame 10-03-2004 02:28 PM

Re: 10. Caveats/warnings
Great job. Wish I had this info a few months back...would have simplified my setup a bit. I saved this thread so that I can come back to it if I ever want to make the change.

Jackdaw 10-05-2004 01:43 AM

Great initiative. I'll try it myself if sound quality is good with the Omnifi. I'd be connecting a Neo.

I was just wondering whether you noticed whether there was a switch that tells the HU that there is a cassette inserted. If so would it be possible to short this so that it always acts as though there is a cassette inserted?

something fishy 10-05-2004 02:12 AM

What we need to ensure if that the headunit detects that both capstans are moving or it will try and eject the tape thinking that it's jammed to prevent damage.

I'm sure that we can short it electrically somewhere, my low tech solution seems to work OK (the noise of the tape mechanism can only be heard when the car is stationary with the engine off) but I agree it would be more elegant to do it your way.

I didn't dismantle the cassette assembly at any point so I can offer any insight as to how you would actually do it.

BTW the Omnifi arrived by DHL yesterday. At present it is in bits having its HDD upgraded from 20gig to 80gig (I figured what's the use of a warranty if I have to ship it to back the the US to claim; finding a cheap way to format an 80gig HDD with fat32 is the immediate stumbling block).

I will transfer my MP3 library onto it overnight and I guess that I will be able to install it over the weekend.

I use a Neo in my other car. It can clip the line ins on a Blaupunkt San Francisco if it's turned up loud enough but I suspect that at 50% volume it will be fine. I'll give you a definitive comment on the Omnifi in situ ASAP.

Jackdaw 10-05-2004 02:19 AM

You can use Swissknife. It's freeware. Download here
Let me know what you think of the Omnifi. Does it take 3.5" or notebook drives?

Jackdaw 10-05-2004 12:12 PM

In pictures 5 and 6 one of the traces appears to say "REEL".
Do you think this may be the signal that says whether a cassette is in the deck?

Jackdaw 10-05-2004 12:18 PM

Also in picture 6 at the top right is a further set of solder points labelled A-GND, L-CH and R-CH. I can't tell from the picture but do the traces go down to where you cut them or are they separate?

If they are a continuation of the same traces then this may be a safer place to cut in order to avoid accidental damage to the other traces. What do you think?

something fishy 10-05-2004 04:59 PM

Hi Jackdaw

To tell the truth I'm not sure what the other A-GND, R-CH and L-CH points do (the head units back in the car ATM).

I'm not an electronics engineer (I just have a healthy attititude toward taking things apart) so I was looking for an easy and obvious solution. I chose the points directly above the connector to the main PCB because they were most accessable and visibly the last point before the signal exits the cassette assembly.

I can say that breaking the traces means that the playback head no longer passes a signal. To be honest I was just clumsy when cutting the traces, it's pretty simple. A jewellers screwdriver is much better for it than a knife however.

Similarly I'm not sure on the "reel" trace. Unfortunately I don't have a way to power the headunit out of the car and the wireharness on the car is very short, so I can't even offer to tst whether or not the REEL trace is high or low when a tape is playing.

Thanks for SwissKnife - its exactly what I was looking for. I in fact created the Fat32 partition last night using Yast on a Linux box that I have lying around for educational purposes (in other words I don't know how to use it). The Omnifi with an 80Gig drive seems to be working perfectly.

The Omnifi uses 2.5 inch notebook drives so 80gig is the highest capacity available at present. First impressions are that it's a much more worked out product than the Neo. Certainly it's screwed together better (not that hard) and has better ergonomics (ditto - even after a year press the wrong buttons on the Neo control panel). That said I've never actually had a day's trouble with the Neo in the car (the foam filled home bay did cook a 160gig HDD once) and the Open Neo project is excellent.

The main drawback AFAIK concerned is that the Omnifi needs client software to load music. I don't object to that per se (the master library can be (and is) on a shared network drive) but it is very slow to transfer a large library as the Omnifi software has first to build a database. It takes about 1 sec per song, too long when you've got 10k+ of them...

something fishy 10-10-2004 04:35 PM

OK the omnifi is now installed so I can give some more definitive feedback.

The line in from the cassette deck works excellently. The Omnifi has a high output (for "hot" MP3s a volume setting of 9 matches 15-16 on CD or radio, for normal MP3s a volume setting of 11 matches 15-16 on the radio) but I can detect no evidence that the input is clipping. In-situ there is a little noise on the line in but this is inaudible at volume settings of less than 22-23 ie. its completely irrelevant in use. Sound quality is much much better than I was getting with either a tape adapter or an FM modulator.

The Omnifi itself is good. Sound quality of the unit excellent. I convert to MP3 using lames -alt-preset extreme and they are the equal of the Bose CD player (in fact they have slightly more bass drive than the CD player). The player is easy to install and shock resistance of the HDD changer unit (at the moment mine is loose in a hollow under the passenger seat) is excellent - I've never had it skip.

Navigating the HDD (I have about 70gig on it - I installed a Hitachi 80gig 4200RPM HDD immediately on receipt) is pretty quick. The firmware could do with a few extra navigation modes adding, sadly unlike the Neo the Omnifi is not open source, but we'll see how they respond to feature requests.

The controller btw is in the nav cubby.

Pictures will follow at some point.



Jackdaw 10-17-2004 04:45 AM

I've just done it myself.
It works very well.
Thanks for the initiative and the detailed instructions.

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