Once again many thanks for all your help and comments etc. Apologies for my slow replies however I haven't been feeling to good in recent days! It's great to know so many people want to try and help.
I confirm the wiring is as per Brian's diagram.
As I'm not used to using them, after reading the multi meter instructions carefully (LOL) I confirm the out put of the transformer is 18.6/18.7 V AC, its labelled as 16V.
The caps haven't blown, there hasn't been any explosions etc, I suspect it's the transistor on the CDU that has gone.
I hope I haven't missed anything, and still suspect its my error in some way or other. Anywat, I look forward to all your further responses.