additional temperature sensors tm11 to tm33 respectively indicate the positions of the additional temperature sensors tm11 to tm33 in the matrix in the direction from below to above and in the direction transverse thereto the output signals of the additional temperature sensors tm11 to tm33 then respectively represent the discharge temperatures t11 to t33 at the regions of the temperature sensors tm11 to tm33 wherein the digits in the designations of the discharge temperatures t11 to t33 correspond to the digits of the corresponding temperature sensors tm11 to tm33 the temperatures t11 to t33 are then used in a manner which will be more fully described later for the determination of a discharge temperature ta depending on the kind of the parts or objects which are presented for the soldering operation only a subset for instance a row or a column of the measuring matrix can be occupied by temperature sensors the cooling chamber 4 which is depicted in particular in fig8 adjoins the oven 3 in the downstream direction as considered in the advancement direction of the workpieces or parts 51a to 51e the cooling chamber 4 is equipped with a controllable blower 71 for an initial slow cooling of a soldered part 51c below the solidification temperature of the solder and a spraying arrangement 74 equipped with valves 76 to 79 for the quenching of the part 51c to a lower temperature with cold water and the rinsing of the part 51c with warm water as well as a blower 72 the outlet of which is aimed in a jet nozzle.