CD Changer Problem
 

My 6 disc cd changer in the boot is not working, I only just tried it out as it never had a cd cartridge when I got the car, so I put some cd's in the cartridge exactly the right way up, pushed the cartridge into the player and tried it out, I pressed the cd button twice on my audi concert 2 radio and it showed that the disc was being loaded and actually playing, but its not, I can select different cd's on the changer but they are not playing, even thought the radio shows that they are, I turned on the radio while holding down the cd button and "Connect" shows up on the radio screen, as I understand this is correct, I have done some tests with VCDS and its not showing any problems, I cant eject the cartridge from the cd changer as it seems like there is no power??

I have also connected another identical cd changer that is known to be working ok, but it still has the same problems, any ideas on this guys??

First make sure the CD cable is connected in the back of the head unit.
If that end appears OK, check that power is available at that end and the far (changer) end.
There may be a fuse for the changer as well.

There are two +12V power circuits in the cable to the CD changer, one is always on (so you can load/eject CDs) and one is probably only on when the head unit is on.

Not sure if your head unit has a label showing the pins on the connector, but it's probably the same as an RNS-D for that connector and their layout can be found easily enough online.
IIRC it's an 8-pin connector with 3 parallel rows of pins - 3,2,3. The +12V pins are the central ones in the rows of 3, though which way round I don't recall.
Easy enough to test with a multimeter.

Somewhere I have the layout of the round connector at the changer end, will dig it out if you need it. Edit: Attached! :D

One slightly odd thing I discovered is that the documentation I found for that plug has the live/switched 12V connectors the wrong way round.
I'm also not 100% sure which way round that pin layout is, i.e. looking at the end of the loom or the plug on the CD changer itself.
But test it with a multimeter and you'll soon find out if there's +12v anywhere. ;)

What can I say, Thank you very much for the brilliant detailed information, I will get my multimeter out tomorrow:)

I only found that out while looking for power sources for my DVB-T tuner, video converter and reversing camera.

Well, I got my multi meter out and checked the plug that goes to the cd changer in the boot, I checked it with the ignition in the ACC and on positions and there was no power on any pin, the weird thing is that the pins are not the same on my plug as shown in your diagram, not all the pins are there and pin 6 is missing, I am sure that they are not broken off, I will have to pull the head unit out and check the plug there for power.

Remember, I said it may be a mirror image, so 6 would be 7, which is unused!

Anyway, no voltage is no voltage, you need to delve behind the head unit!