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Resident Whippersnapper
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Discussion Starter · #1 ·
Hi there fellow Opelers. If you've got a working original AM radio in your GT (or Kadett, maybe even Manta?) but want to listen to your MP3's, here's a fairly simple way to do it. You'll need a working radio, a soldering iron, some wire, 1/4" and 16mm sockets (to get the face plate off) and a jack, preferably a 3.5mm size standard aux jack. I used an old 1/4" telephone switchboard jack, 'cause it's contacts are all exposed (so you can see what's going on inside) and it was what I had laying around.

You start by removing your radio from the dash. Mine was already removed, so all I had to do was pull the knobs off.
 

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Resident Whippersnapper
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Discussion Starter · #2 · (Edited)
You then remove the two 16mm nuts on the volume and tuning posts, then remove the 4 1/4" screws holding the face plate on. This will expose the volume/tone potentiometers.

You will want to modify the wires going to the volume potentiometer (the bottom thingy with the three lugs), of which there are three. The black one on the left is a ground, the green one in the center goes to the amplifier part of the radio, and the blue one on the right is the signal wire from the radio receiver part of the radio.

I added a brown wire to the black ground wire, left the green wire alone, disconnected the blue wire (and soldered a black/white wire to it), and soldered a black/green/white wire to where the blue wire was on the potentiometer.

When you're listening to AM and the aux is unplugged, the black/white and black/white/green wires are connected. When you plug in the aux, the black/white wire disconnects, and your source connects to the black/white/green wire and the brown ground wire.
 

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Resident Whippersnapper
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Discussion Starter · #3 ·
Next, the hard part. You'll need to connect the ground wire to the part of the jack that connects to the base of your aux cable. The black/white wire connects to what is called the "normally closed" part of the jack, i.e. the part that connects when the aux cable is unplugged, and is disconnected when your aux is plugged in. The black/white/green wire connects to either the part of the jack that conects to the middle or tip of your aux cable. Then you connect the two parts of the jack that connect with the middle and tip of the aux cable with a resistor, 80-220 ohms. I used two 300 ohm resistors in parallel to give me a value of 150 ohms.

Now assemble your radio, put it in your car, mount your aux jack somewhere, and crank up your tunes! You'll get AM with the aux unplugged, and surprisingly good (mono) sound with the aux plugged in, just don't set your MP3 player too loud or you'll get distortion. Enjoy!
 

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Resident Whippersnapper
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Discussion Starter · #6 ·
Well, here it is installed in the dash panel, I would've gone with just a little hole, but I drilled too close to the radio, so I had to drill a bigger hole so the jack could fit through, then I put that cover plate on... If you do it right you'll only have a little hole next to the radio, or you could put longer wires and mount the jack elsewhere.
 

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Well, here it is installed in the dash panel, I would've gone with just a little hole, but I drilled too close to the radio, so I had to drill a bigger hole so the jack could fit through, then I put that cover plate on... If you do it right you'll only have a little hole next to the radio, or you could put longer wires and mount the jack elsewhere.
Nice Mod! I'm putting this on my list of things to do.

Thanks!!

Gary
 
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