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Thread: Connecting an iPod to JVC KD-G720 (help with pinout?)

  1. #1
    Newbie
    Join Date
    Jan 2010
    Posts
    1

    Connecting an iPod to JVC KD-G720 (help with pinout?)

    Hey guys, i'm new here, and fairly new to the whole car audio world..
    I've installed and hooked up HU's/amps/speakers in cars, and I'm really into building/modding guitars/guitar amps and effects.
    ..just so you know I'm definitely capable when it comes to electronics, I've just never done anything like this before

    as my title says, I'm trying to hook my 3G touch up to my JVC kd-g720.

    I know JVC sells an ipod adapter, but from the little bit of information I've found, it's not entirely compatable with the newest generation..
    so, of course, I'm going to have a go at making it myself.

    heres what I know so far:
    I'm gonna be using a j-link connector, plugging it in to where the cd-changer or ipod adapter would normally go on the back of the HU. as far as I know, it's the same connector as alpine uses, as well as sony.
    so if I can't find a cheap j-link one, I can look at them. for now I'll stick with the j link, cause I know for sure it's what I need, though.

    ok, so I got the j-link pinout from an older thread on here:


    I also have an idea of the dock connector's pinout. for what I'm interested in:

    1- Ground
    2- A/V ground (connected on the iPod's motherboard to 1)
    3- Right line out +
    4- Left line out +
    11- *
    15- Ground
    16- USB ground (connected to 15 on iPod motherboard)
    21- **
    23- +5v (usb power)
    25/27- usb data***


    *- on a 3G iPhone, pin 11 gets grounded to send signal through 3 and 4 (line out). if pin 11 is left open, the internal speaker gets used. the info I've found about 3G touch tells me it should work the same way. anyone know anything about that?

    **- accessory indicator. different resistances to ground tell the ipod what accessory is plugged in. again, I only have info for the iPhone 3G and 2G touch.. so I'm guessing about the 3G touch unless someone comes in and gives me a confirmation that it'll work the same for my 3G touch

    ***- again, for 3g iphone and 2g touch, but.. I'm hoping it'll work for mine: pin 25 needs to be at 2.8v, and pin 27 at 2v. that'll force the ipod to charge.



    So I pretty much have 2 goals:
    1- get my ipod to play through the line out and into the car system. I dont think I'll have as much trouble with this one.

    2- get the ipod to charge when the HU's on.


    for goal 1:
    -pin 3 of the ipod to pin 6 of j-link (right channel line out to right line in)
    -pin 4 on ipod to pin 8 of j-link (left ch line out to left line in)
    -pin 2 on ipod to pin 7 on j-link (audio grounds)

    to force the ipod to send the line out, I need to ground pin 11 (to pins 15/16).
    I also need to connect pin 21 to ground (15/16) with a 68k resistor, to play through the line out instead of the internal speaker.


    goal 2:
    I still need to figure out what sort of load resistance the iPod's gonna show, but once I do that, I'll figure out what resistor values I'll need to drop the 12v from the HU (j-link pin 1) down to 5v.

    - connect that 5v to ipod pin 23 (usb power)
    - power ground will be j-link pin 4, and ipod pin 16.
    - to force charge, I'll drop the 5v to 2.8v and 2.0v, and connect those to ipod pins 25 and 27, respectively.


    ..so.. has anyone done anything like this, or does anyone know more than me about the workings of the 3G touch?
    if my 3G works the same as a 2G touch, I think I'll be in the clear, but I figured I'd run it past you guys first..

    any help/advice/anything?

    also, sorry if this isn't the right forum. but I'm a car audio noob, so I figured I'm safe here for now

  2. #2
    Newbie
    Join Date
    Apr 2010
    Posts
    1

    Does it work well?

    I'm looking to make the line-out modification to make my car kit work with my new ipod touch 3g and I'll be glad if you can confirm it work well.

    Thank you!

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