Black 20pin miniiso connectorthis connector has pin lock which need to be unlocked befor inserting pins, this is how it's look from booth sides:
Use screwdriver os something flat to push lock on side which is on previous picture, lock will slide inside few milimeters:
On the other side it will popout:
This is how its looks inside of connector:
and after unlock:
CD changer ground pin in mini iso connector
If your radio has ground pin(CD-GND) as this one has (in this case audi concert2) connect emulator like is on next pictures (but insert pins all way down). Take attention to power pin, red one, it must go to switched output pit, in case you put it on constant +12V emulator will probable not works, maybe for first time.
audio cable goes here:
CD changer ground in 10pin tel/nav connector
if your radio is for example audi chorus/concert1, ground pin for CD changer is on 10pin connector on this picture, upper right, but body for this connector is to expensive for low budget project like this emu, so ground connection is made by cable fastened to metal chassis of radio. Screw has torx T-9 head.
In case you have pre-ampifier, this one is powered from constant +12V pin, righr audio channel is also red, but goes from shielded cable pare, I marked it with pinkish color:
grounding goes to chassis: