C33 AUX input and Installation Megathread

[kronus]

I got my C33 in the mail! No more Sony Xcrap here we come!

This thread is a reference on C33 installation in general, and much of it can be applied to the C43, as well, since the two radios are similar. Post any questions and/or guide requests.

Table of Contents

0) Information
1) Disassembly
2) AUX input modification, Reassembly
3) Harness Modification
4) Installation
5) Amplification

Guide Status - Incomplete

0) mostly done
1) done
2) done
3) writing
4) waiting for parts to come in
5) researching

[kronus]

0) Information

Tools and Equipment You Will Need

Phillips screwdriver. small size
Soldering Iron. thin point
Solder. thin, flux core
Drill + metal bits. You'll need a 1/4" and a 3/8" bit.
RCA-headphone cable. This goes from our new AUX input to a MP3 or a CD player
Crimps. Because apparently soldering the harness is bad, according to latest research.

2x RCA jack. Get one Red and one White
3x 2" pieces of wire. Conventionally, Red, White, Black (or whatever colors you prefer)

The radio

The radio model I am modifying here is a C33 tape deck from a 1998 BMW 323is.



It has a top. And a bottom. (this picture is of the bottom)



It also has a back, on which we see four plugs.



Starting from the right, we have the Big, L-shaped connector, with a 7.5 amp fuse over it, as well as the smaller, 10-pin I-bus connector. The pinout for these connectors, reproduced from here, where there is also more useful information about CD-changers:




I'm not entirely sure (yet) about the lack of separate grounds for front and rear speakers, I've seen pins 8 and 11 used in addition to 12 and 14 to provide four separate grounds on another diagram.

The I-bus connector does not concern us, although there may be a way of hacking it to provide AUX input instead of the tape.

Then, in the middle, we have the 'Diversity Reception Antenna Control' jack, and finally, leftmost, the antenna jack.

In the very center is a metal extension forcefully screwed into the backing plate and covered with a plastic sheath. I have no clue what it does, but I'm removing it because it annoys me.

[kronus]

1) Disassembly
(some images here are clickable for larger versions)

Start from the back. There are two screws that hold the top plate on to the chassis of the radio. Here they are, taken out. The cover then lifts up from the back, and comes off.


My radio was damaged either in shipping or at some other point. Doesn't look fatal, I hope...


Continuing, we will now unscrew and lift out the tape receptacle. There are four screws that you need to take out, marked red:


After you unscrew these screws, you should be able to carefully take out the tape receptacle. There is a plug between it and the main circuit board, so expect some resistance. Here's the removed tape receptacle (I love that word too much)


There is a shiny metal shield on the left side of the receptacle, held on by two short screws:


Remove them, but be careful, as they are tiny, easily-losable mofos. With the shield removed, you can finally see your goal - the little solder points this process has uncovered are the ones we need in the next section.

[kronus]

2) AUX Input Modification, Reassembly
(some images here are clickable for larger versions)

Allright. Now, we have our radio nice and disassembled. Look at the back-left corner of the tape receptacle:



The vertical row of pins on the right is what interests us. Going up from the bottom, we have Ground, Left channel +, and Right channel +. In diagramatical form:



Get three wires, each about 4 inches long. Make sure they're different colors. The standard colors for Left, Right, and Ground are white, red, and black. Since I'm special, I decided to use green, orange, and black. (they're the only solid copper wire colors that I have. Color doesn't matter, as long as the three are different). You do not want to use stranded wire, because it's more difficult to solder and more annoying to deal with.

This is the hardest part of this modification - soldering three wires onto the pins I pointed out above. I can't really advise you much about it, except that you should be doing this with a fine-point soldering iron (not a solder gun, for fuck's sake) and extremely thin solder (.015" is perfect). A Radio Shack iron is allright if you get the pointy tip for it, the 45-degree tip that comes with it is mostly useless. Photos are, as usual, worth 1000 words, so here are some.

Start with this:



(you'll note that the wire colors here are different from what I mentioned above. This is the stranded wire that I screwed with for half an hour before giving up and going to solid wire)

Finish with this:




Make sure that the solder isn't bridging from pole to pole. You can do this with a multimeter, or even a regular test light. Also, make sure that the joint is solid, and that you can't twist the wire out of the solder by as little as bending it gently.

Now that that's done, our attention turns to the backing plate and the jacks. Remove the backing plate from the head unit by taking out the four screws on the back. Then, pull the plate away. There are two power transistors that have a thermal paste coating on them, and this paste is likely all over the back of the plate. It's safe to wipe it off the plate, but make sure that the transistors make sufficient contact with it and have enough paste on them when you put it back. Here is the plate, removed, with thermal paste:



The jacks I got from Radio Shack:



These are exactly what we need, and they're great because they have threads and nuts on the back. Typically, the ones you can steal out of old TV's and amps don't have that luxury and you have to affix them with a less solid method, like hot glue or hooker spit. The threaded part's width is 1/4", and the plug base diameter is a little smaller than 3/8".

You also need to figure out where you want the plugs to be. The best and most obvious place is on the left of the plate, above the big hole for the antenna plug.

We run into a problem, however. The threads on these plugs are exactly as long as the backing plate is thick, which means that the nut can't even get onto the threads. This means we have to countersink our mounting holes. First, drill with a 3/8" bit until you have between 1/16" and 1/32" of vertical wall inside your holes. Then, finish them off with a 1/4" bit in the center of the countersink hole. My drill press wasn't the greatest, so it didn't come out very neat. Nothing that can't be fixed with a file, though. Here's the result:



And here are the plugs, mounted in the holes:



You'll want to bend the tabs up so that it is easier to solder to them. Then, take a small piece of wire and bend it into a [, which you can then suspend in the tabs and solder to the jacks easily:



Now, you should mount the backing place back onto the radio before you connect everything back up, because it's easier that way. Trust me. Here's the plate mounted back onto the radio:



And here it is, with the wires soldered to their respective jacks. It's convenient to put the Right plug on the right of the Left plug, for obvious reasons.



Finally, put the cover back on, and button it up:



Now, all that remains is hoping that it still works.

[kronus]

3) Harness Modification

3a) Testing

So, we have a complete radio. We now need to see if it still works. To do this, a power supply is needed that provides a solid ground and +12V. There are many different ways to accomplish this, but my preferred way is hacking a desktop Power Supply Unit (PSU). You probably have a bunch of old computers with these in them lying around somewhere, or know someone that does. This process is reversible, so don't worry about breaking the PSU (unless you're not careful, in which case you deserve it anyway). The particular one I use here is actually out of a server, so it's small, but the idea and the process is exactly the same. Here's my PSU:



Click here for a superb in-depth explanation of how to make that unassuming computer power supply into an all-purpose lab supply. What follows is my abridged version.

Things needed:

Jumper wire - At most an inch and a half, with a bit exposed on each end, long enough to fit into the biggest connector of the PSU and big enough to stay.
LED - You typically don't need this, but it's useful to know that your supply is on at a glance. Some older supplies do need it, though.
10 ohm 10 watt resistor - get two of the big ones at Radio Shack (they come in a package of two), or steal one from your parts bin.

A great tool to have is a Molex connector extractor:


Anyway, gather the above parts together, and grab your power supply. The big connector (the one that typically goes to the motherboard) has either 20 or 24 wires going to it. The colors of these wires are important and useful. Here's an outline:

ALL the black wires are grounds. ALWAYS.
RED is +5V
YELLOW is +12v
GREEN is Power On
GRAY is Power Ok
the rest of them are unimportant to us right now. If there's interest, I can do a more in-depth writeup of how to hack these power supplies.

Grab your small piece of jumper wire, and connect the Green wire's pin to a ground pin. It doesn't matter which one, they are all soldered together inside the PSU anyway. Then, grab your LED, and notice that it has a long lead and a short lead. The long lead is positive (+), so stick it into the Gray wire's pin. (you may need to double it up for it to hold). The shorter lead is ground (-), so stick it into a ground pin. Finally, grab your big resistor, and connect the +12V pin (there should be only one) to a ground pin. The resistor is omnidirectional, so don't worry about orientation. This is what you should end up with:



Now, make sure that the switch on the back of the supply is set to 0 (off). Plug it into the wall, and switch the supply on. You should see the LED light up and the fans in the supply should start spinning. If you have a multimeter, now is a good time to check if you're getting good voltages. Grab your multimeter, and one of the 4-wire strands coming out of the power supply. The strand should have 1 red, 2 black, and 1 yellow wire, and end with one or several "Molex" connectors. Test the voltage between red and ground:



then, yellow and ground:



Eh, close enough for government work :)

So, we now have a working supply. You may have noticed that it's sitting on top of a big, old speaker-looking thing. This one, actually:



It's an old-skool a/d/s that has been sitting outside of my dorm room for a while. It doesn't sound particularly great with any amp I've thrown at it, so shrug. It'll be a good test mule, as I will have to struggle hard to blow it.

So, turn your attention back to your power supply. If you haven't turned it off, you will notice that the resistor has gotten really hot. This is unavoidable, but don't worry about it; those resistors are rated up to 275 degrees Celsius. Turn it off, and if you don't have a proper connector yet, grab your molex tool and take out a bunch of the pins from one of the 4-wire leads. Don't worry about the red ones, we won't need +5V.

Referring to the pinout diagram I posted earlier, begin wiring the head unit up to the power supply. You should end up with one lead going to +12v, one to ground, one to speaker +, one to speaker - (I chose to start testing with the left front speaker), and two loose wires for Ignition and Illumination. You can snip these off the harness if you don't care much about your supply, or use some other form of connector. Basically, you want to be able to touch +12v with either of those wires at any time you want.

This is what I ended up with:



Now, make sure that nothing is shorting, and power up the supply. Verify that the fans are spinning and the LED is lit up, and examine the radio. It should have started blinking its little light, surprised at having power all of a sudden. Take the Ignition wire, and stick it into a source of +12V. Then, press the volume knob, and if you've done well so far, you get this:



I have no idea why it shows up purple. It looks normal IRL.

After you put in the radio code, it should go into normal operation. Verify that all the controls work, and grab a tape that you don't care about. I had found a bunch of old classical tapes in the same place where I found that power supply, so I had a half hour of fun pulling the tape out of the cassette, which is unfortunately not pictured. I swear it made a great wig.

Anyway, stick your tape in, connect the aux inputs to your computer or MP3 player, and try to play some music. Because I only had the one speaker, I had to test one channel at a time. The test setup in action:



Also, take the Illumination wire, and touch it to +12V. You should see the display dim and the backlight for the buttons come on. Make sure to not touch it to ground, or you'll short the radio and blow the fuse. This is it lit up, and my camera blue-ing the crap out of the display for some stupid reason:



That's it so far; I need to get the damn connector so that I can write up the rest of this section.

[kronus]

4) Installation

I will recommend that you run new speaker wire. The stock E30 wiring setup involves a fader and a common ground setup, which is not advised for upgraded head units.

[kronus]

5) Amplification

I will initially be installing this setup without an amp, to see how it sounds. If it's inadequate, amp discussion and installation pictures go here.

[TDE30]

Sick, looking forward to the finished product.

Subscribed.

[PiercedE30]

Yea, using the IBus connection with my iPod has made a HUGE difference in sound clarity and quality versus just listening to different radio stations. There is also a dramatic change in volume between the two. I would love to run an amp with mine.

[kronus]

TDE30 - this one's for you :P

PiercedE30 - Do you use an existing IBus adapter? I'm going to try out a little thing I thought of, mainly putting AUX through the IBus connector. It most likely won't work, as the HU probably expects some sort of handshake before going to the IBus. Also, is it noticeably quiet without an amp? Luke mentioned that it can only drive like 7W, which is sort of lame...

Anyway, going to go look for a radio shack now.

[PiercedE30]

Well, there is definitely a difference in volume output when I switch between a radio station and my iPod. There is definitely a hand shake needed to activate the IBus system. I remember reading something on here about somebody building a PCB that would trick the IBus system into activating and was actually able to play music off of his computer through the radio using the adapter he made. I think he had to program a microcontroller after he figured out what signals the radio was sending and figuring out what it expected to receive. I don't know if he ever finished it. It was either on here or on E30Tech.

[StereoInstaller1]

According to all I have found, the ibus stuff started in '96, so this earlier radio will NOT directly control an iPod...there is an AUX input, which seems to work well enough, but is expensive for just an input.

I am currently working on an E34 Touring with a CD43 (1999 deck) running into 2 Exile Shift series amps, along with a Peripheral iPod controller.

The hassle I am up against is that the E34 has a 1992 wiring harness...but fortunately, I have a '99 E36 to compare it with, and steal plugs off of.

I can tell you that by soldering RCAs on the ends of the speaker wires from the CD43 and plugging them into the amp(s), even using the remote wire already run to the stock amp, everything is perfect...no noise, excellent sound quality, flawless everything so far.

Expect to see this insane E34 with supercharged 3 liter S52 in Performance BMW one of these days, along with the stereo setup....all Exile, all work by yours truly.

Pics and writeup here first, of course, along with my shitty pics.

Luke

[StereoInstaller1]

Kronus, do you have the same connector/pinout for the later radio, like the 96-99 E36?

BTW, that little metal prong with plastic doo-dad is the rear support that most beamers use...

[kronus]

How much did the pinout change? I have one that's labeled for 1995 radios, and one for a 2003 e46 that is a similar shape, but has independent grounds for all the channels.

(speaking of the grounds, the pinout claims that the grounds are combined for left & right channels. Is this because of an odd interface with the e36 amp, or can I just twist LF- and LR- together and stick them onto that ground pin?)

Also does the e30 use the metal prong-support? I remember peeking back there and not seeing any orifice for it...


Work on this has been slow, because I need to find a drill press. I have not forgotten, though.

[StereoInstaller1]

How much did the pinout change? I have one that's labeled for 1995 radios, and one for a 2003 e46 that is a similar shape, but has independent grounds for all the channels.

First, the deck should not have independent grounds, so that is really not so much of an issue.

In the E34 I just finally finished, pin 7 went to the OBC as a data bus. I left it as a databus, but chopped "Tel Mute" since no telelphone was being used and used it to get a databus signal to the ass end of the car.

The changer connector on the '92 was a 13 pin cable, but only a few wires were used. I cut the end off and attached the changer end of a cable off of a '99 E36.

Pin C (3 pin harness: +12V, Ground and data) of this '99 cable (yellow) went to pin 7 (brn/blu) on the deck, then red/white and grey/black (or whatever the shielded cables were)

So basically, 1 wire "modded" and a cable end swap were all that was necesssary to make the iPod adapter work.

(speaking of the grounds, the pinout claims that the grounds are combined for left & right channels. Is this because of an odd interface with the e36 amp, or can I just twist LF- and LR- together and stick them onto that ground pin?)

What are you doing for an amplifier?

Also does the e30 use the metal prong-support? I remember peeking back there and not seeing any orifice for it...

No, I dont think any E30 has that rear support

Work on this has been slow, because I need to find a drill press. I have not forgotten, though.

Yeah yeah, whatever.

:)
Luke