A mounting arrangement for a circuit board on the neck of a cathode ray tube includes a guide member formed in the cathode ray tube base. The guide member is formed to have a surface extending perpendicular to the tube longitudinal axis. The circuit board incorporates a socket having a channel for receiving the guide member for aligning the socket on the tube base. A portion of a locking piece is inserted through a hole in the socket wall in order to abut the perpendicular surface of the guide member to prevent removal of the socket from the tube base. A second portion of the locking piece forms a hook which cooperates with the socket to prevent inadvertent removal of the locking piece.