Tests accuracy of flow meters, pressure gauges, temperature indicators, controllers, radiation counters or detectors, and other recording, indicating or controlling instruments to locate defective components in system, using test equipment, such as pressure gauges, mercury manometers, potentiometers, pulse and signal generators, oscilloscopes, transistor curve tracers, and ammeters, voltmeters, and watt-meters. Traces out and tests electronic solid state and vacuum tube circuitry and components to locate defective parts in analog and digital, protection, or radiation monitoring systems, using test equipment, schematics, and maintenance manuals.