  In 2015/16, the photomultiplier cameras of the H.E.S.S. Cherenkov telescopes
CT1-4 have undergone a major upgrade. The entire electronics has been replaced,
using NECTAr chips for the front-end readout. A new ventilation system has been
installed and several auxiliary components have been replaced. Besides this,
the internal control and readout software was rewritten from scratch in a
modern and modular way. Ethernet technology was used wherever possible to
ensure both flexibility, stability and high bandwidth. An overview of the
installed components will be given.
