A hot fluid preparation unit for a fully automatic coffee machine is specified. With the goal of reducing the heating-up time of a fluid, the solution according to the invention provides that the hot fluid preparation unit has a temperature control device, a fluid heating arrangement, a rectifier circuit and a power semiconductor switching device. The rectifier circuit is connected at an input of the rectifier circuit to an AC voltage supply and at an output of the rectifier circuit, via the power semiconductor switching device, to the fluid heating arrangement. The power semiconductor switching device is designed in a controllable manner such that it selectively switches through the output of the rectifier circuit to the fluid heating arrangement. The temperature control device is configured to control the power semiconductor switching device in a pulsed manner, in order thus to perform a temperature adjustment.