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Old 16th March 2009, 22:25   #1
BoneyTony
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MG ZT-T 135+ diesel

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Thumbs up Symphony + CD changer - facelift models

Here is a guide to making a compatible Alpine CD changer work with the Symphony head unit in a facelift 75 or ZT, using the existing CD changer (IOVOX) connecting lead in the boot and the small blue ISO connector for the head unit. I’ve also assumed that you’ve changed the wiring of the grey ISO connector so that the Symphony works properly as a radio cassette.

I bought my Symphony & changer in June ’08 just after I bought the car, and spent many months reading forum posts & scratching my head with bits of wiring loom all around me. I had 2 'Eureka' moments which led to me solving the puzzle of why 2 compatible components wouldn't work in a 'facelift' ZT but obviously do work together in the older models.
  • The Symphony & changer will not work if you simply connect them together using all the correct plug pins. I know, I've tried! They MUST be connected via the car's K-Bus circuit (which feeds through the body control unit). This explains why the 'pre facelift' glovebox connecting lead does not simply connect the blue mini ISO to the CD connector, it has also integrates with other circuits, inc the K-Bus.
  • Although the wiring loom is different in facelift models with different colour coding, the car’s K-Bus wires are still coded Red / White / Yellow.
To do this job you need to be happy wielding a soldering iron, and you need a large bottle of persistence & patience!

HEAD UNIT END


Task: to connect the Symphony’s K-Bus feed to the car’s K-Bus ring

Method: Pin 19 on the blue ISO is the K-Bus feed out of the Symphony. You need to remove the white wire (plus any others attached to the pin – mine only had one) from Pin 19 of the ISO plug, & replace it with a K-Bus wire - Red / White / Yellow. I found mine feeding a small flat 4 pin plug taped to the audio loom connected to nothing, which I now know is for the low-line sat nav system – see picture. I bought the correct ISO plug pins from www.nexxia.co.uk. The white wire is too fine for a Scotchlok connection. You could cut the white wire leaving the plug pin intact & solder the K-Bus wire to it; I removed it complete with the pin (you need patience & a jewellers screwdriver to flatten the 2 tangs on the pin to do this) & attached a new pin to the K-Bus wire, inserting it into the ISO plug. That’s all you do at the ‘head end’.



BOOT END - CD CHANGER
Task: To connect the CD changer to the car’s CD cable and to the K-Bus ring.
Method:
You need a suitable lead with the small oblong 10 pin socket that connects to the changer’s plug. The VUL100320 lead often supplied is fine.
The cable that connects up to the old IOVOX CD unit terminates in a circular 8 pin DIN plug. You can choose to leave this intact and connect a suitable 8 pin DIN plug to the changer cable (as I did), or not bother with plugs & hard wire the CD player lead to the car’s cable.
You need to buy a suitable DIN socket from Maplin & be ready for some soldering.


The connections are as follows:
Note: DIN Pins numbered clockwise looking towards the CD cable, i.e. looking at the BACK of the socket that you need to solder, or the FRONT of the plug in the car. Pin 1 is to the left of the 'notch', 7 is to the right, 8 is in the centre

DIN socket pin 1 connects to the K-Bus. I used the Red / White / Yellow wire (using a 'scotchlok' piggy back) that connects to the parking sensor module on my car as it's below the CD changer. I think the loom is still there on “non-parking sensor” cars. Other connections:



The 10 pin oblong CD changer socket (on the separate lead that you hopefully have) has the pins numbered - you may need a magnifying glass to see them! To help, looking at the face of it, pins 5 & 10 are at the end with 2 lugs sticking out sideways - pins 1 & 6 are at the end with 1 lug.



Pin numbering (10 pin CD connector, description, then 8 pin DIN, then blue mini ISO + wire colour for info if you want to check continuity)



1 = Yel/Blk = Audio Rt +ve; DIN pin 2; ISO pin 14, green
2 = Blk/Yel – Audio Rt –ve; DIN pin 3; ISO pin 17, red
5 = Wh/Red/Yel, K-Bus (see text); DIN pin 1 (see text); ISO pin 19
6 = Pink/Blk, Audio Lf +ve; DIN pin 5; ISO pin 13, brown
7 = Blk/Pink, Audio Lf –ve; DIN pin 6; ISO pin 16, yellow
8 = Black, Chngr earth; DIN pin 4; ISO pin 15, orange
10 = Purple, Power; DIN pin 7; ISO pin 20, blue

Make sure the soldering is secure & there are no shorts - remember that power is fed down this cable as well as signal & earth.


My thanks to STUBIE for his post on 8th April '08.




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