Build and install your own AUX Cable!

[sk93]

I believe they're actually outputs, but don't quote me on it... i certainly couldn't find any obvious use for them!

Ah

I'll perhaps look at using the NAV/TV and VCR inputs on the other plug then - looking at what the TV modules are going for I don't think I'll be adding night vision for a while anyway

I've managed to rip a couple of connectors out of some old PC header cables, so with a bit of luck I'll have the right capacitors/resistors knocking about to get something soldered up - unfortunately, left my flippin' soldering iron at work so I'll not be doing it tonight, doh!

hehe.. i'd be interested to see where you get with it, as the info for our headunits is sketchy at best and i think i'd like to play around more

those connectors will do the job just dandy , but you will want to insulate the sides of them, as they will be touching each other once plugged in otherwise.
If you have an old case-mounted pc speaker / power/reset switch, these are perfectomundo for what you want them for

 

[sk93]

SK93 I think you hit the nail on the head. I see no resistors or capacitors on the cable I have purchased. I will add per your schematic and hopefully all will work. Thanks for your help.

check for continuity between the left and right audio channels.. if there is none, then it won't work without said ressies and caps :wink:

I can 100% guarantee that if you follow this schematic, the cable WILL work

 

[Siftah]

1x 300kΩ 0.6W Resistor - Maplin Part No: M300K - £0.16
2x 0.22uf Capacitors - Maplin Part No: WW56L - £1.12

Well, everyone must have decided to make their own because Maplin is out of stock of 300kΩ resistors!

I'll use two 150kΩ in series as I have them in my box of junk. Also haven't got any tantalum caps so I'll replace those with polybox's.

Now, to the soldering iron!

 

[Siftah]

Well, I made progress but not great...

I had a feeling tantalum caps were polarised, so I googled a bit to find out and during the course of this I noticed that other people on BMW forums had successfully made working cables without using the capacitors at all. The consensus seemed to be that the caps are just there for filtering and aren't essential, so I left them out!

That seemed to make sense (can anyone explain what the capacitors actually do?) so I went ahead and made a cable up using just the resistor(s).

I've verified I have 300kΩ resistance between the left/right audio channels, but the cable doesn't work - AUX-IN isn't shown on the radio, it just cycles through Radio/CD/Intravee as before.

sk93,
I noticed there's an inconsistency in the pin numbers given, in your original post you mention:

RED PIN - #8
GREEN PIN - #9
BLUE PIN - #4

Yet the schematic posted above points to pins 3,4 and 10 being the necessary ones. The schematic seems to match up to what I have connected already (ie: the NAV is using pins 11 and 5) but maybe I'm missing something here?

Also, the pins I'd sourced from an old ATX PSU seem too big to fit properly into the connector used in the car - the pins from a USB header cable seem to be a better size, in fact the connector on the car looks to be two standard sized PCB header pin connector cables slotted into another connector (hence it looks a lot bigger in the photo I posted earlier).

I think I'll re-solder my cable using the smaller size pins and then try again tommorrow - but now, a beer and bed

 

[sk93]

the caps are used to filter out some of the noise that can/will be generated along the cable.
they are also used to help maintain a constant "volume" in.
I tried without them, and although the cable worked, it wasn't very good.


In regards to the numbering, when I made my cable and this howto, I didn't have an english version of the pinout above.
I had a dodgy german one and it wasn't brilliant.

however, looking at the backside of my radio at the time, I was certain the pin numbering on the radio started from the bottom left pin being number 1, and the top right pin being number 12.
wheras in the pinout i posted for you counts from the top left to bottom right.

This is definately the pins you will be wanting to connect up, regardless of numbers
(I know the pins off by heart due to the amount of times i've plugged/unplugged it now)
If you just forget the pin numbers and use those, I promise it won't go wrong.


It's likely the connectors aren't holding the pins - have you any reset/power switches you can "recycle"?
However, if you can take a piccie of where you've connected up your cable to the stereo, I may be able to spot what's wrong?

 

[sk93]

however, looking at the backside of my radio at the time, I was certain the pin numbering on the radio started from the bottom left pin being number 1, and the top right pin being number 12.
wheras in the pinout i posted for you counts from the top left to bottom right.

and yet I was wrong

I've whipped it back out this morning and the second schematic is correct.. the numbering is from top left, to bottom right.
I've now updated the schematic for the wiring and also updated the original post to reflect this

cheers!

 

[Siftah]

the caps are used to filter out some of the noise that can/will be generated along the cable.
they are also used to help maintain a constant "volume" in.
I tried without them, and although the cable worked, it wasn't very good.

Ahh, that concurs with what I read - I'll be using a Line-In source so I think I can get away with out them, my understanding is that the capacitors are more relevant for using a headphone level source. As I've gone ahead and already soldered up the cable I'll give it another go with the smaller pins this afternoon and see how it sounds.

(For info: I'm using the line-out port from my TomTom mount for the iPhone 3GS. This takes a Line-level output from the iPod Dock connector on the bottom of the iPhone, so I should be OK to skip the capacitors and get a slightly cleaner sound.)

I've whipped it back out this morning and the second schematic is correct.. the numbering is from top left, to bottom right.
I've now updated the schematic for the wiring and also updated the original post to reflect this

\o/ This is the most complete and best photographed documentation I found on the web, so I'm happy to have helped make it even better

It's likely the connectors aren't holding the pins - have you any reset/power switches you can "recycle"?
However, if you can take a piccie of where you've connected up your cable to the stereo, I may be able to spot what's wrong?

After my post last night I found an old USB header cable which I butchered and used those pins instead, soldering them into my cable. I've photographed it to document it on here later, but as yet I've not managed to test it on the car (my day-job is interfering with my car modifications!). I'm hopeful these will work better and they'll certainly fit into the connector better as far as I can tell.

(I'm adding pins into an existing plug, rather than just adding pins to the open connector, so I'm unable to use the single header pin cables but rather extract the metal plug from the plastic casing then insert it into the existing plastic plug - I'll document this later with photographs as it's difficult to explain!)

 

[sk93]

i know exactly what you're on about in your final paragraph.
Ideally, I'd have liked to have a plug already there on mine.

I'm planning to retro BT later in the year, so I'll be taking more photos and expanding this guide then, but if you can beat me to it

you're sort-of correct with the lineout theory. It will certainly have less volume issues, but you are still likely to get noise, based on all the jacks and sockets along the route.. tbh though, you may never notice it, so give it a whirl without - it's only a five minute job to add them in later if needsbe


the USB header pins are a perfect fit btw

 

[Kaide]

I'm having trouble finding the required parts... I cant find any .6w resistors here... Is there an equivalent in the States?

Also, I was thinking, instead of having a socket in the dash, I was thinking of having a longer cable probably routed through the ashtray, but with a male end on it. Would the creation of this cable be any different?

 

[Siftah]

I'm having trouble finding the required parts... I cant find any .6w resistors here... Is there an equivalent in the States?

Hey, they generally come in 1/8th Watt, 1/4 Watt and 1/2 Watt values - 0.6W is ~ 1/2 watt.

The larger of the three are 1/2 watt and will do just fine, they're usually about 3mm wide by 9mm long. You tend to find they're the most common, your local radio shack or similar should have plenty in stock

Also, I was thinking, instead of having a socket in the dash, I was thinking of having a longer cable probably routed through the ashtray, but with a male end on it. Would the creation of this cable be any different?

There's no reason why that shouldn't* work - I decided to take an existing cable and cut one end off, that way my plug was a nice moulded plug and is likely to stand up to a bit more abuse. There's nothing fundamentally different about making a cable this way, you just have a little less soldering to do as you've only one end of the cable to solder. Pins 3 and 4 will be the right and left channels and those will be white and red coloured in your cable. Red for left, White for right. You'll then have 2 thicker and probably unshielded wires which will be the earth. You'll need to join those together and make sure they go to pin 10, the earth.

* Though, see my next post...

 

[Siftah]

No joy for me

I've tested the cable and it definitely seems to be correct electrically speaking. I've checked each wire with a multimeter and there's continuity across all the cables, 300kΩ resistance between the left and right channel and the pins are all making good contact. I still don't get an AUX-In option on the radio though

I ended up buying some of the single pins from Maplins and using those to test, the ones in the photos below were too big to fit into the existing plug so I decided to bypass them and connect straight to the pins on the back of the radio - still no joy

For interest and reference, this is what the cable ended up looking like:



Close-up of the way the resistors are soldered into the cable, bridging the left and right channels.


All heat-shrinked and ready to go - fairly neat and tidy and easy enough to hide in the dash without fear of it falling apart. I decided to leave a plug on the end rather than a socket as I wanted to run this through the dash and out the right hand side above the instrument pod. The idea is to use this as a line-in socket from my iPhone TomTom car mount. That would mean I could opt to play music from the iPhone via the TomTom's line-out socket if I wanted to. It'll also let me stream music over the 3G connection, or even play TV shows on the iPhone and have the sound through the HiFi.

Anyway - I've not given up yet, I'll have to do a bit more pondering and have another go at this :\

Things I've left to try:
- Leaving the cable plugged in whilst the car is off and goes into deep sleep, then it'll do a cold boot and maybe it needs a cold boot to recognise a new AUX-IN socket?
- Re-do the cable from scratch, just in case it *is* a dodgy cable and my multimeter isn't showing it up for some reason :\
- Perhaps I should try and use something else with a line-out socket, rather than just testing with the iPhone/TomTom.
- Put the damn capacitors onto the cable, maybe they *are* there for a reason other than filtering after all...

 

[Kaide]

Things I've left to try:
- Leaving the cable plugged in whilst the car is off and goes into deep sleep, then it'll do a cold boot and maybe it needs a cold boot to recognise a new AUX-IN socket?
- Re-do the cable from scratch, just in case it *is* a dodgy cable and my multimeter isn't showing it up for some reason :\
- Perhaps I should try and use something else with a line-out socket, rather than just testing with the iPhone/TomTom.
- Put the damn capacitors onto the cable, maybe they *are* there for a reason other than filtering after all...

Please let me know how this works for you... As soon as you posted that pic of the resistors I was like... "Where are the capacitors?"

If that would work, I'd feel much more comfortable using an existing cable, adding some capacitors, resistors, and ends then starting fresh.

 

[Siftah]

Please let me know how this works for you... As soon as you posted that pic of the resistors I was like... "Where are the capacitors?"

If that would work, I'd feel much more comfortable using an existing cable, adding some capacitors, resistors, and ends then starting fresh.

I'm 100% sure that using a moulded plug rather than a socket will make no difference to the circuit

I've come across this page this evening which gives more explanation for why the capacitors are there, this guy mentions uncoupling the audio circuit, which I'm not entirely sure I understand but it at least points to the fact my circuit probably isn't working because of the lack of the capacitors!
http://www.cosninix.com/blog49/index.php?entry=entry060313-010827

 

[Kaide]

These connectors in this photo? do they work as well as the computer connector pins... or do they touch when connected to the radio?

 

[Siftah]

These connectors in this photo? do they work as well as the computer connector pins... or do they touch when connected to the radio?

Those were the ones I found were too big, I swapped those for standard header pins (USB header or similar). Even then, they won't fit inside the plastic casing of the original connector so you'll need to replace the existing connector rather than splice the connector into the existing plastic housing.

 

[VsKoen]

Just made the cable as instructed capacitors and resistor in place and it works as promised on Professional radio with bluetooth Tv and Nav. Be sure to have the right capacitors and resistor otherwise it won't work you definitely need them!!

 

[Siftah]

Things I've left to try:
- Re-do the cable from scratch, just in case it *is* a dodgy cable and my multimeter isn't showing it up for some reason :\

Well, I redid the cable from scratch with the capacitors in. Still no dice. I've left it plugged in and the cars off and locked at the moment, so I'll see if I have any luck once it's done a cold boot. Looks like either I've buggered the AUX-IN pins with my earlier messing about or there's something else weird going on :\

Only difference from the spec was that I used polybox capacitors rather than tantalum, as again, that's what I had in my parts box at that capacitance. :\

 

[jhbuining]

Siftah, the resistor should be on the side of the head unit, so there you should read 300kohm resistance. The side of the head-phone plug shouldn't read that. Did you put the resistor on the right side of the capacitors?

 

[Siftah]

Siftah, the resistor should be on the side of the head unit, so there you should read 300kohm resistance. The side of the head-phone plug shouldn't read that. Did you put the resistor on the right side of the capacitors?

Seemed to be measuring fine - anyway, I re-made the cable again and it's now working, Woo!

I suspect it was just crappy soldering - I couldn't get the soldering iron to tin properly today, will have to get some cleaning paste for it and sort that out before my next electronics project. I'd probably killed the caps with too much heat or something before, who knows, certainly works now anyway

The sound level is a lot lower than the Intravee or the radio, which is a bit frustrating. Plus you can hear a bit of noise too which mostly seems to be from the iPhone itself (would dissapear in Airplane mode no-doubt).

It means I can now play music/video via the iPhone and listen to the sound on the cars speakers anyway, so I'm happy - managed to hide the cabling away behind the dash and pop it out next to the steering column near the iPhone mount so it's a reasonably tidy install.

I think my next job will be to take the cigarette lighter socket plug for the TomTom/iPhone and hardwire that into a power feed behind the dash which is only live with the ignition. I hate having the plug in the cigarette lighter socket all the time, looks so untidy. After todays ham-fisted attempts at soldering that can wait until next weekend

The single pins from Maplin are well worth buying, whether you've got the bluetooth audio plug installed or not. With the pins you can leave the existing plug as-is and use the Maplin connectors to extend it and then glue together the new connectors to make a replacement. Glueing them together will make them easier to plug in I think (I haven't done this myself yet).

Cheers all - will post some pics later

 

[Kaide]

I think my next job will be to take the cigarette lighter socket plug for the TomTom/iPhone and hardwire that into a power feed behind the dash which is only live with the ignition. I hate having the plug in the cigarette lighter socket all the time, looks so untidy. After todays ham-fisted attempts at soldering that can wait until next weekend

FYI, I can guarantee that the 12v to the cigarette lighter is hot 24/7, ignition on or off. Just keep that in mind before you start splicing.