Vintage Electronic Service Manual - DAVID BOGEN model 2AR & 2RS 2-tube office intercom inter-communication system. Manufactured by David Bogen Company, of New York, NY. Dated 1947. 2 pages. Original old Sams Photofact manual includes schematic, layout, voltage & resistance test chart, repair parts list and description. This manual would make a sensational accompaniment to your retro office equipment.