The preamplifier boards for CHAOSJunior were soldered according to slightly modified scematics of the High Energy Telescop (HET) experiment. For the detector setup of the balloon flight in September 2023, only four preamplifers are necessary and only those four were assembled for now. Since the HET preamp board has room for twelve preamps in total, more can be added at a later time for the detector setup of CHAOS. The assembled preamplifier board was tested for any short circuits and function of the operating points. The boards are working as desired and can now be tested further with attached detectors.