Hi there my drayton 711 timeswitch loses it's memory when power to c.h boiler is switched off. From what I understand from the instruction leaflet it should have battery back up for this eventuality. I have opened the unit up but can't find any sign of a battery or even where a battery may have been fitted. I phoned Drayton and was told that the battery is soldered into the pcb and it's similar to a watch battery. Well there's nothing which even resembles a watch battery on the pcb. Can anyone please help me identify where this elusive battery may be hiding? Any help would be greatly appreciated. The system was fitted circa 1995. 
