– 33 –CHAPTER 1 General7.5 Range of Faults Specification(1) Upon receiving a fault report from a station user or an operator, the technician can assume a faulty cardexists if the range affected by the fault can be determined. For the detailed procedure, refer to Chapter 6.Use the following actions to check the MDF:(a) Check the LENS of the reporter (Station or ATTCON/DESKCON).(b) Check other circuits of the circuit card in which the reporter (station line or ATTCON/DESKCON) islocated.(c) Check the other groups (other circuit cards mounted in the same module) in the module in which thereporter is located.(d) Check lines in each of the other modules on the basis of multiple lines.(2) If the fault cannot be detected by the system (a fault related to the speech path such as noise during speech,one-way speech, speech inability), the range of (a) through (d) (itemized above) should be limited.(3) When a major fault is detected in the dual systems, the CPU or TSW system automatically changes over ifthe fault range is (c) and (d). In this case, the whole module involved is placed into make-busy status evenif the fault is partial, and the station lines currently operating normally become faulty status. Diagnose thefault from the content of the system message displayed and repair the fault as required.(4) To narrow down the range of faults, consider the system circuitry that consists of the control (see Figures1-17 and Figure 1-18, where CPU 0 is active) and speech path systems (see Figure 1-14 and Figure 1-19).(5) As seen from the block diagrams in Figure 1-14 through Figure 1-19, if a fault that affects the commonportions occurs, all other associated portions will be affected by this fault. When CPU and TSW are pro-vided in dual configuration, they will be automatically changed over as far as the fault is detectable by thesystem.
