Great post.
I've been trying to do this on my stereo but running into some problems:
2003 Outback Wagon Limited with 6CD/9-speaker P122/P128 headunit with Weatherband feature.
- My CD player is busted so no JazzyMT kit for me.
- the
Leptronix kit which works without a CD costs more than a new headunit so not for me either.
Tapping into the FM receiver output seems like a slam dunk.
The FM receiver module in the 2003 headunit is *exactly* the same as the 2005 unit. In fact I have both stereos (2005 was a spare) and dissected them side-by-side to compare. I found the right and left audio output pins from the FM module.
When I attached an old Sony Walkman, it worked great and I heard FM+walkman mixed. When I attached a cellphone, I just get a loud click like its passing DC or something and both signals were blocked. I tried two different cellphones both of them Windows phones and same thing. I got my multimeter and tested the output of the cellphones and I can't see any DC on the leads, but my multimeter isn't terribly accurate. I did measure about 70K-ohms between left and right audio channels. Not sure if that is noteworthy.
The weatherband receiver module has only MONO output so can't really use that for music. But I attached the cellphone to that anyway and heard the cellphone audio just fine. Plugging my cellphone into my home stereo works just fine too.
Weird right?
Edit: I figured it out. I believe the output stage on many digital devices switches off when an input in the audio frequency range is detected or the measured impedance is in a particular range. In the case of cellphones based on Qualcomm chipsets, the headphone jack is a multifunction device that acts as:
- headphone output
- microphone input
- switching for controls
- FM antenna
So it is a fairly complex device. All I had to do to get it to work was to NOT mix the cellphone output and Subaru radio FM signals together. Instead I switched them with the radio-shack 3.5mm jack that has 5 pins as originally proposed. When the cellphone is not plugged in, the signal from the FM radio loops through the 3.5mm jack on its own and back to the amplifier. When I plug in the cellphone, that circuit is broken and instead the cellphone is connected directly to the amp. Works like a champ now. I successfully modified both a 2005 single-CD player and a 2003 6-CD player and integrated the jack right into the faceplate of both stereos for easy access. No need to run a cable around the back and into the cubby. Just plug and play.
The 6CD player was a lot more difficult to work inside. I had to partially de-solder the Weatherband radio and flip it down out of the way so I could get to the pins on the FM radio. Very tedious and probably not worth the trouble. But pretty straightforward on the single-CD player without weatherband.
I may get an in-line 3.5mm ground loop isolator as well so I can charge my cellphone while playing music without any hum:
[ame]http://www.amazon.com/Kensington-Reducing-SmartPhone-including-iPhone/dp/B0031U1ATQ/ref=sr_1_3?ie=UTF8&qid=1376848964&sr=8-3&keywords=3.5mm+ground+loop+isolator[/ame]
Just need to find one that uses quality transformers and doesn't degrade audio quality too much that isn't a huge brick.
Pics to follow.
