Auxiliary Port for Any Radio/Cassette Player (Monsoon From Jetta MK4)

So I’ve purchased one of my favourite cars last summer, the 2001 Jetta TDI. For a 2001, it was a pretty amazing package. It had an immobilizer, power windows, a sunroof, A/C, heated seats, leather interiors and all the bells and whistles that anyone could have ask for. Even though it had CD changer inputs, it unfortunately did not have an auxiliary port. So in this instructable, I’ve successfully created my own. Just a word of caution, following this instructable will void all warranties and will no longer make the cassette player operable. Please be advised that the audio output will not be of high quality. Another instructable will be created to solve this... Let’s begin!

Step 1: Tools

Tools:
Radio/Cassette Removal Tools
Screwdrivers
Scissors
Soldering Iron w/ solder
Tape
Wires
3.5 mm jack
3.5 mm male to male cord
10K Ohm resistor (brown black orange) x 2
Dremel or drill

Step 2:

Step 1:
Remove radio/cassette player using manufacturer's tools.
Step 2:
Remove top cover by removing the two screws, then prying gently with a bladed screw driver.
Step 3:
Disconnect the magnetic head from the circuit board and cut off the ribbon wire.

Step 3:

Step 4:
Solder on five new wires to the connector. If you look on the other side of the connectors, it will show the inputs as Common, Front Left, Front Right, Rear Right, and Rear Left.
Step 5:
Solder the Right inputs together and the left inputs together.
Step 6:
Solder a 10K ohm resister (brown, black, orange) between the connector and the 3.5 mm jack. Add tape to prevent shorts.
Step 7:
Solder the other end to a 3.5 mm jack (Sleeve=Common, Ring=Right, Tip=Left).
Step 8:
Plug 3.5 mm male to male cord into the 3.5 mm jack.

Step 4:

Step 9:
Carefully pry the faceplate off.
Step 10:
Using a Dremel or a drill, create a small hole in the cassette door for the cord.
Step 11:
Put everything back together and replace radio/cassette player to the vehicle’s dash.
Step 12:
Turn the volume on low for both the device and the radio/cassette to test for audio.

Comments

[fasteddiera64]

Thanks. I have done this to two car stereos. As long as I use my phone running on its battery, it's great, but if I use anything that's plugged into the car, it's super noisy. On one car a ground loop isolator fixed it. On the other, the isolator makes it sound weird. Like "this is broken" weird.

Any tips on creating an isolated power supply for a source? I'd like to use my Echo Auto.

[indy2588]

Hello, thanks for the info. I've done the aux input mod myself on a couple tape decks, I've found that if you input the audio after the tape head amplifier IC it will sound much better. The amplifier has way to much gain for line level audio to be fed to it even with resistors. This last one I did had a MC4558 8 pin IC. If you google the IC chip you can find the output pins. Remove the IC and solder your left and right wires to the output pins, then ground to chassis ground. On the tape mechanism that I removed is had a switch that senses the tape is present. Wire these two wires to a toggle switch, epoxy the old tape door down and mount the switch to the door along with a 1/8 phone jack for the audio. Its also nice to change out the tiny incandescent panel bulbs with LEDs, if its an old player and with all the jarring around with this mod the bulbs probably wont last much longer.

[claudiopolis]

The tape head preamplifier must be de-soldered or rendered un-operational by cutting the power line. If you leave it like this you'll still get a lot of noise as the output pins of that preamplifier have a permanent voltage differential.

[fduraibi]

thanks for the amplifier trick, i will try it. Since I have tried the direct wiring to the head and it sounded so bad.

[eric999]

Hi, I've been wanting to hack my car stereo for a while and stumbled upon this article. I'd like to try it because I think it would be a fun project, but I'm a complete electronics newbie, so I have a couple (probably stupid) questions for you. First, is there a particular type of wire that I should buy for this project? And second, I was confused about which connections I need to solder the resistor between. It sounds like I'll have three connections - left, right, and common, going from the circuit board connector to the 3.5mm jack. Do I solder one resistor between each connection, or something else? I see two resistors in the pictures you posted, which I presume correspond to the left and right connections, but I don't see a third, so I wanted to check to make sure. Thank you for this very informative article and I hope I have the same success!

[VentingIntrovert]

The quality of the audio from the hack was so terrible that I didn't even bother anymore. It's not worth your time.

[micah.croft]

Just how bad is the audio quality? my cassette player isn't working, so I cant use a cassette adapter.

[fduraibi]

in my case the sound was so bad that i prefered listing directly from my phone or using headphones over using it.

[claudiopolis]

Check this one:

https://www.instructables.com/id/AUX-IN-and-Bluetooth-for-Every-Car-Casette-Player/

[VentingIntrovert]

Bad enough that I wouldn't bother trying.

[claudiopolis]

Indeed, it's one incomplete solution. For a much better one, see my instructable. You can get pure digital sound on it.

[tomaskovacik]

do this, or buy:

https://www.tindie.com/products/tomaskovacik/vwcdp...

;)

[jj.inc]

This is pretty cool, but why not just spend three dollars on a cassette mp3 adapter that doesn't ruin your casette player.

[fduraibi]

I have tried two cassette adapters and both sounded bad, also they won't give you stereo sound, or one channel will be stronger ...etc

[VentingIntrovert]

Good question...The main
reason I chose this over a cassette adapt is really to illuminate as much
distortion or interference as possible. I believe that if an analog signal is
converted to a magnetic wave, transferred across a gap, received then converted
back to analog, would certainly be in loss of quality from the transmission. However, by eliminating certain parts of this process, by theory it should help.

[xKOBAYASHIMARUx]

Technically this only works with radio/cassette players with some sort of input that's already supported; ie cd changer port. For many stock radios this will not work.

[VentingIntrovert]

That is false... It will work for all radios with a cassette head. We are bypassing the cassette reader head in order to obtain an input. Obtaining an input from the CD changer port is much more difficult and requires specific protocols as the radio will require constant communication with CD changer in order for that input to be accepted. I've done the research. Google "Monsoon CD changer protocol", or "VWCDPIC". It gets complicated, but I'm working on this new approach as well.

[Ian74]

Couldn't you just fit an aftermarket stereo?

[VentingIntrovert]

That costs money... I'm broke :(

[TheSurvivor99]

Shouldn't you have blurred the license plate?