She returned to Wilhelmshaven for periodic maintenance from 2 December to 3 January 1940, after which she resumed training duties. During the shipyard period, a degaussing coil was installed just above the waterline to protect the ship from magnetic mines and her anti-aircraft armament was strengthened. After the work was completed, Emden returned to training duties through the winter of 1939–1940.[15][16][17]