Common impedance coupling of shield current at equipment inputs and outputs - the pin 1 problem

Neil Muncy\´s landmark 1994 paper (N. Muncy, 1994) identified the improper termination of cable shields (to a circuit board rather than to a shielding enclosure) as a primary mechanism coupling EMI into audio equipment. He called it "the pin 1 problem" because pin 1 is the designated shield contact for the XL-connectors widely used for audio. The problem exists with both balanced and unbalanced wiring, and is addressed by a new AES standard. (AES48-2005, 2005) It has been shown (J. Brown, 2003) (J. Brown and D. Josephson, 2003) that pin 1 problems are a common cause of RF coupling into equipment pin 1 problems abound in professional and consumer equipment of all sorts.