Quite a useful document if you need to repair your beebs CUB monitor!
microvitec-series-3-colour-displays-service.pdf
Also, this is the TTL RGB output pinout diagram.
    Blue Green        Hsync      Vsync     Red         GND
Please note : Wiring diagrams on this site are provided as is. I cannot be held responsible if you damage your quipment or yourself, either through errors in the wiring diagrams or through any errors that you may make when ssembling the lead. Also remember that electricity (especially mains electricity) is dangerous. Take care when working with it.