An AC/DC converter is operative to receive, via AC input terminals, an AC input signal and to transform the AC input signal into a DC output signal. The AC/DC converter comprises a first DC discharge circuit coupled to AC input terminals. The controller comprises a second DC discharge circuit having a controllable switching element for switching the second DC discharge circuit on and off. The second DC discharge circuit is operative to receive a DC discharge current from the first DC discharge circuit; logic associated with the AC/DC converter repeatedly: receives a DC sense signal from the second DC discharge circuit and determines, based on the value of the DC sense signal within a predetermined measurement time period, loss of the AC input signal. In response to determining loss of the AC input signal, the logic controls activation of the second DC discharge circuit depending on the DC sense signal.