An in-line heating device (1,2,3,4) for a liquid food or beverage preparation machine in which liquid is circulated through the heating device and then guided into a brewing chamber. This heating device comprises: a thermoblock with a metal mass (1) that incorporates an inlet, an outlet and a heating chamber extending therebetween to form a passage for guiding said liquid circulating through said mass, the mass being arranged to accumulate heat and to supply heat to the liquid; and one or more electric components (60,70,75) that are rigidly secured onto or into the thermoblock and that are connected to a printed circuit board (4) and/or a flex-print (4') arranged to control the thermoblock. The electric components are rigidly connected to the printed circuit board and/or flex-print, in particular via rigid connector pins or blades or rigid plug and socket members.