  In the framework of the upgrade of the Pierre Auger Observatory, a new high
voltage module is being employed for the power supply of the 1-inch
photomultiplier added to each water-Cherenkov detector of the surface array
with the aim of increasing the dynamic range of the measurements. This module
is located in a dedicated box near the electronics and comprises a low
consumption DC-DC converter hosted inside an aluminum box. All the modules have
undergone specific tests to verify their reliability in the extreme
environmental conditions of the Argentinian pampa. In this paper, we describe
the validation procedure and the facility developed to this aim. The successful
results of the tests on the HVPS modules are presented and discussed.
