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