A print head of an ink jet printer comprising: a cavity for the circulation of jets, delimited laterally by side walls, at least one nozzle for producing at least one ink jet in the cavity, at least one generator applying a charge to at least one ink jet, at least one electrode for sorting drops or segments of one or several of the jets intended for printing from drops or segments that are not used for printing, a slot, open onto the exterior of the cavity, a 1st gutter for recovering drops or segments not intended for printing, a 2nd gutter for recovering drops or segments that are not deflected and not intended for printing, this 2nd gutter comprising an input slot and at least one suction channel, an actuator in order to actuate the 2nd gutter, a 1st detector to detect an electrical charge of drops recovered in the 2nd gutter for recovering when the latter is in a closed position and/or a detector to detect, without contact, the passing of charged drops when the 2nd gutter is in an open position.