CHAPTER 8 GENERAL SUPPORT MAINTENANCE INSTRUCTIONS

ARMY TM 5-6675-238-14 MARINE CORPS TM 08839A-14/1 CHAPTER 8 GENERAL SUPPORT MAINTENANCE INSTRUCTIONS Section I. GENERAL 8-1. Scope of General Support Maintenance. General support maintenance consists of bench testing the SPU, tape reader, and cable assemblies; preventive mainte- nance checks and services; testing and troubleshooting the SPU and tape reader; removal and replacement of SPU and tape reader components; and repair of cable assemblies. 8-2. Signal Processor Unit Bench Testing. Bench test- ing of the SPU consists of performing continuity checks when broken or shorted wires or failing switch or relay contacts are suspected of causing a failure during per- formance of the self-test procedure. A schematic dia- gram of the SPU (figure FO-18) and wire lists (table 8-1 and 8-2) are provided for bench testing. Refer to para- graph 8-6 for an explanation of wire list format and notations, 8-3. Tape Reader Bench Testing. Bench testing of the tape reader consists of performing continuity checks when broken or shorted wires are suspected of causing a failure during performance of testing and trou- bleshooting. A schematic diagram of the tape reader (figure FO-19 or FO-20) is provided for bench testing. Column Signal From Compo- nent Pin To Compo- nent Pin Ref AWG Type 8-4. Cable Assemblies Bench Testing. Bench testing of the cable assemblies consists of performing a Point-to- point continuity check. A wire list (table 8-3 is pro- vided for bench testing. Refer to paragraph 8-6 for an explanation of wire list format and notations. Color 8-5. Preventive Maintenance Checks and Services. To ensure that the PADS test set is always ready for operation, the preventive maintenance checks and serv- ices must be performed as outlined in table 8-4. Definition Numbers or letters appearing in this column are used for logic terms and signal identification and are assigned per their respective circuit func- tions. Entries in this column denote point of origin. Entries in this column denote point of termination for items in the From Component Pin column. The suffix letter A, B, C, etc. defines which of several wires attached to the same pin is intended. The suffix letter S defines the shield of wire connected to this pin. Standard wire size for tables 8-1 and 8-2 are 24-gauge, except as noted, Standard wire size for table 8-3 is 22 gauge, except as noted. Symbols in this column specify con- figuration of a wire or wires. In the absence of a specific symbol, stan- dard insulated wire is intended. For flexible printed wiring, this column is not applicable. Standard wire color is white except as specifically color-coded. Numbers are coded to a color as follows: Number Color 0 Black 1 Brown 2 Red 3 Orange 4 Yellow 5 Green 6 Blue 7 Violet Change 1 8-6. Wire List Format and Notations. Tables 8-1 and 8-2 contain wire lists for the SPU and SPU front panel, respectively. Table 8-3 contains a wire list for the cable assemblies. The following paragraphs define wire list format and notations. a. Wire List Format. The wire list column head- ings, from left to right, are listed with their respective entries defined as follows: 8-1