FAULT LOGIC DIAGRAMS

Table 1-6.—Sample Maintenance Turn-On Procedures Some of the primary equipment troubleshooting may also include internal indications at key test documentations are covered in this subsection, includ- ing fault logic diagrams, signal-flow diagrams, pyra- mid diagrams, relay and lamp indexes, and relay lamp ladder diagrams. Also included is a sample equipment troubleshooting problem relating to a simple checkout procedure. FAULT LOGIC DIAGRAMS.— Fault logic dia- grams (FLDs) are used to speed troubleshooting by requiring the technician to answer a branching series of questions about an observed system fault. The questions, which permit only yes-or-no answers, per- tain primarily to the status of external indications (lamps, dials, meters, scope displays, etc.), but they points. By a process of elimination, the technician is led to the area of probable trouble and is referred to equipment troubleshooting documents. Figure 1-4 shows a sample fault logic diagram. SIGNAL-FLOW DIAGRAMS.— Signal-flow diagrams show the signal flow from an input to an output function. Adjustment procedures, replacement procedures, and schematics are referenced in the signal-flow diagram to provide the technician with quick access to the appropriate maintenance require- ment cards and related troubleshooting documenta- tion. Figure 1-5 shows a sample signal-flow diagram. 1-17