by German Alvarez German
Alvarez
Version 1.1, 2005-04-20
Part of the iPod installation into a Saab 932001
convertible described here
Disclaimer
This was done in what I assume is the factory radio of a Saab 932001
convertible car. I’m not responsible to what can happen to your car by
doing this modification. This also requires significant experience and
the ability to use potentially dangerous tools. If you still want to do
it, here are the instructions. It will probably violate the warranty.
This will disable the possibility to use the external CD changer.
The changes are reversible if done in a careful way.
Goal/How it works
The main goal is to feed an external audio signal to the radio. The
external CD changer connection is used, but since the radio will not
let us select this input, after the input
stage and just before the preamplifier the signal is rerouted into the
telephone input. Using the external "TEL-MUTE" pin the radio can be
instructed to select the telephone input.
This is a very simplified block diagram of the radio and associated
systems before and after the modification.
Before:
After:
The iPod interface is an optional part of this setup, that maintains
the current functionality of the onStar/telephone interface and adds
one input for the iPod and one additional AUX input. It also conditions
power for the iPod to operate it and charge the battery and signals the
iPod that it should operate in the "dock mode". If this functionality
is not required then just perform the modifications to the radio
described here.
To use it, feed a line level (headphone may work but be careful) signal
to the "CD IN LEFT" and "CD IN RIGHT" pins, and connect the ground of
the signal to the "CD GND LEFT" and "CD GND RIGHT". I spliced the
connections into the existing cables, but there is the potential for
noise pickup because the cables go all the way to the trunk of the car.
You may want to cut the existing cables if your system picks noise. I
did not do it because I want to keep modifications to the minimum. A
good option is to connect a standard 1/8 phono jack.
After this modification grounding the pin "TEL MUTE" will activate the
external signal. The SID will display "TELEPHONE"
The treble and bass controls will not work for this signal, but the
balance volume and fader will operate normally. The telephone input
volume is independent of the volume form other sources, read the manual
for more information.
Identify the radio
Does it looks like the one in this picture? (click for large images)
and here is the label on top:
If it is the same continue.
Open the radio
Remove the screw indicated in the picture. Ignore the black cable
coming out from one ventilation slot, it was part of a previous attempt.
Cut traces
Cut the traces indicated on the picture.
Solder two short pieces of insulated cable connecting the locations
show here. Make it flat enough for the lid to close. Using a tiny cable
(i. e. 24 gauge) and starting from the little holes to the left will
make it easier.
Here is how it looks in my setup. I bet you can do a much better job!
