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The job isn't really that bad, and you're just working on the tape deck, so the worst you can realistically do is damage the tape deck, not the whole stereo. As this modification basically replaces the tape player, all normal functionality (steering wheel controls, volume, etc) still works. Of course, you don't have the ability to control the iPod remotely like the TrollPod will.
See the linked website (bottom of the page) for illustrated instructions. The following text is some additional information that is very useful to anyone attempting this modification. The source of this information cannot be mentioned here, but it is written by a person who goes by the name 'opjose'.
This solution is brilliant for many reasons, but in needs some additional minor changes.
What this modification does:
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The modification intercepts the signal going from the Tape deck unit, to the audio pre-amplifier. With a switch and jack (or wire as [ed. on Dangie’s linked website], though see below for a better alternative...) the audio from your MP3 player is routed to the pre-amplifier directly, as if the MP3 player were the tape deck unit itself.
Why this is good;
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Much better S/N ratio than anything else.
No induced noise from outside sources.
No low end roll off and a tad better high end response.
If done properly, it looks much cleaner.
Ability to hide all wiring.
Coolness factor.
Why you might not want to do it.
___________________________
Extra work.
Cassette adapters give good results which are ALMOST comparable. [ed. not in my opinion]
You can screw up your stereo if you don't know what you are doing.
Voids warrantee on stereo.
Why this solution is "brilliant".
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The tape pre-amp input, expects 388mv PtP current... guess what MP3 players put out? Yup, same thing!
No additional circuitry is needed.
Reversible (see modifications to Dangie's design below).
Does not impact normal function (see modifications to Dangie's design below).
If you screw up, you may only be affecting the tape deck which can be swapped out with a pulled (cheap junkyard) unit WITHOUT requiring a Tech II remarrying!
Drawbacks:
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Tape unit must be running (engaged) to hear MP3 player.
The best way to engage the tape unit is to use a cassette adapter and cut off the provided cord. This will keep the capstan spinning and the tape unit active, but will not actually run tape past the head, so the only wear and tear is to the capstan impeller. [ed. I had to disable the tape player's "automatic fast forward through silent sections of tape" functionality to keep it from constantly fast-forwarding. I don't recall how to disable this, but it is in the owner's manual.]
Modifications to Dangie's design:
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Dangie's idea is brilliant, and I assume that he and Michael worked without schematics.
A set of schematics would have revealed that you DO NOT have to cut the traces!
Refer to the picture with the words "Very carefully (!!) make a cut with...." under the picture...
Notice the two horizontal surface mount resistors immediately above the cut he made.
Those are 0 ohm resistors. That means that all they do is jumper or bridge the circuit between them.
If you remove the resistors, you could just as easily substitute a wire in their place and things would be no different.
Get the picture?
Instead you can remove the resistors and take the lower side (closest to the cut) to the CENTER poles of a DPDT switch, and the upper side (closest to the black IC chip just above them) to ONE SIDE of the DPDT switch. When the switch is turned to bridge the connection, the cassette/tape deck works normally.
The other side of the DPDT switch, gets it's input from your MP3 player. This can be done via an input jack (as I am going to do) instead of Dangie's hardwired plug.
I would also suggest a quick release plug so that some unknowledgeable shop tech, doesn't accidentally rip out your handiwork, in trying to remove the Stereo Head unit.
No CUTS required!
The beauty of this is you can always later place a wire in place of the resistors, or restore the resistors and the radio will be as before.
Also since all modifications have been done to the tape "module", which is easily removable, you can always swap in another one.
The item which is married to your car, is the much larger motherboard (circuit board) which remains unmodified.
You can swap CD player modules and Tape deck modules without having to worry about needing a Tech II.
So there you have it, the first fully viable MP3 AUX in solution for the 9-5's.
Additional explanation of DPDT switch implementation:
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Adding the switch is almost trivial.
Look in the picture where you can see the "cuts" Dangie made.
DO NOT cut the circuit board, instead desolder (and save) the two green resistors immediately above the cut.
Now wire in a DPDT switch...
The CENTER poles of the dual position switch connect to the "lower" side of the resistor pad (what is left over when you desoldered the resistor...).
The "lower" side is the left most portion in the picture, and it is electronically "closer" to the main system board...
On a DPDT switch you have six pins.
The TWO center poles of the switch, become the left and right channel INPUTS.
Wire up the right side pads of the now removed resistors to one side of the DPDT switch. When the switch is "on" it will bridge the circuit, restoring the original tape deck function... Test with a meter to make sure you've done it right.
Finally the other two remaining "pins" or poles of the switch respectively become AUX input Left & Right (or Right and Left...)
Anything connected there, will be heard via the stereo when the switch is "off".
The easiest thing to do is to connect a jack's top two conductors to the remaining pins.
Finally remember that you also need ground... that is the tape deck's ground (obtainable ANYWHERE on the deck with a ground) should be connected to the jack's ground, or rather it's outermost "ring". This grounds the MP3 player's ground to the Deck Unit's ground.
The ground connection is "active" at all times.
While I've given a rather long explanation, it's much easier than it sounds. [ed. see image for further clarification]
Imagine a switch in place of those two green resistors and you get the idea.
posted by 68.14.69...
Dangie's 9-5 AUX in instructions
, Tue, 21 Nov 2006 08:30:22, Wed, 22 Nov 2006 09:22:57, Tue, 21 Nov 2006 15:31:09, Tue, 21 Nov 2006 17:27:43, Tue, 21 Nov 2006 09:47:24
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