a state of a technical device in which at least one of its main or supplementary parameters deviates from the requirements stated in technical specifications. A device may become faulty because of failure or damage.
Failure makes a device inoperative, since in this case at least one of the main parameters does not conform to specifications. Damage does not necessarily make a device inoperative; it may remain operative if the deviation from technical requirements is confined to supplementary parameters. An example of a device that is faulty but operative may be a radio receiver with all main parameters still within the required limits but with a burned-out lamp for illumination of the tuning scale. The same radio receiver would become inoperative in case of a break in the powersupply circuit or a failure of an electron tube (or transistor) in one of the amplifier stages.