A cryopump system includes an integral assembly having a refrigerator, cryopumping surfaces cooled by the refrigerator, a first electronic module for controlling the cryopump, and a second electronic module which is removably coupled to the first module. The second electronic module has a first surface abutting a complementary first surface of a housing of the first electronic module. Preferably, the first controller module has three orthogonal surfaces of approximately the same dimensions. Electronic modules can be removably coupled to each of the three surfaces. The cryopump system includes a module cap which is coupled to an end of an electronic module to shield electrical connections between two coupled electronic modules. The electronic modules comprise a channel of rectangular cross section having slots for mounting printed circuit boards.