technical diversions

a place to document my current project of connecting an iPod to a Saab 9-3 convertible with the factory audio system.

Monday, January 31, 2005

got a radio with aux-in!

ok, yesterday i accomplished two things, modify the radio to take the AUX input and wire the car.

I could not find a convenient spot to put a 1/8 stereo jack on the body of the radio then i decided to go with a "pigtail". It was cheaper to buy an "extension cable" with a male and a female 1/8 stereo jack and cut it than to buy the materials.

Here is the pigtail from the back:

And here is inside the radio, cable is routed to the front where if goes under the circuit board:

Here is where the cable is connected. In addition two modifications have to be done to the circuit board, cut a trace between the TEL-R and TEL-L to isolate the channels (the telephone is monophonic) and cut a trace that carried the original signal to the preamplifier.

Then i now have a radio with an AUX input! :-)

Since the car is a hostile environment with a lot of vibration that can wear the insulation of cables it is better to provide additional protection for all the cables. I use an expandable braid that is easy to work with, provides good protection and gives a neat appearance.


  • At 31 January, 2005 21:42, Anonymous Anonymous said…

    What is the sound quality like? How do you initiate the radio to switch to the sound coming from the aux-in/tel-in?

  • At 31 January, 2005 22:02, Anonymous Anonymous said…

    "cut a trace that carried the original signal to the preamplifier"

    Where is this cut made? I see the first cut you talk about, but what about this one, can you post a pic of where this cut should be made.

  • At 31 January, 2005 22:26, Blogger jason1321 said…

    why do you need to cut the trace that carried the original signal to the preamplifier? Where do you make this cut?

  • At 02 February, 2005 19:28, Blogger gatoAlfa said…

    here are some answers to the comments:

    * sound quality is excellent, at least that was my perception when i tested it.

    * the cut is on a trace that carries the original signal. The cut can be seen in the picture where the cables are soldered. Look carefully to the left of the ribbon connector. The trace that is cut is the one that ends in the TEL-R pin.

    * the signal level coming to from the onStar system is about 4V PP, there is some attenuator network to bring this signal to about 1V PP that is on the TEL pins of the preamplifier. I decided to cut the trace to avoid any interaction with the existing circuit. This may not be required.

  • At 23 May, 2013 11:38, Blogger Alim Baytekin said…

    Hi there,

    Currently i took out my 1999 Saab 93 stereo to have an AUX In. I am keep looking at circuit board for TEL-R and TEL-L, which i located, however i can't seem to follow thru where to cut the trace? Mine looks like not touching at all


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