an anti - theft security device and alarm for detection of the disconnection of electronic equipment such as video cassette recorders from a series electronic signal path loop is disclosed . the chassis of the vcr or other electronic audio - visual equipment is used to complete a series connection between a security circuit and a ground potential signal so that disconnection of the electronic equipment on diplay from the sucurity circuit will cause an open circuit condition . the open circuit condition is detected by an alarm circuit , and the alarm circuit responds by producing an alarm signal which is supplied to audio and visual signalling devices to produce audible and visible theft alert signals .