Could anyone point me in the right direction for a wiring diagram for the circuit board inside the box please?

The box in question is the mains charger under the R&R bed, Westie Club Joker 1.6 TD 1986, black thing that charges the batteries when van plugged into mains.
Rest of items within work fine, but board U/S. Have a magic ferret (pet leckie) on it, but he could do with a diagram. Have tried Wiki, Bentley and previous threads but haven't found anything. (may be thick here, and not recognise it)

Alternatively, will now be looking for replacement 2nd hand board/2nd hand charger/replacement charger. Any hints, tips or otherwise in this direction please?
Thanks guys, 'preciated.
Myk.
