ARMY  TM  5-6675-238-14 MARINE CORPS TM 08839A-14/1 Section III. TROUBLESHOOTING 8-8.  General.  Troubleshooting  of  the  PADS  test  set consists of performing the self-test procedure (table 8-6 or 8-6.1) and fulfilling the corrective action if a mal- function  occurs  during  the  procedure.  Table  8-6  is performed using tape reader, part no. 877406-1, and table  8-6.1  is  performed  using  tape  reader,  part  no. 877406-2.  During  the  self-test  procedure,  the  tape reader is checked for proper operation, Paragraphs 8-10 and 8-11, and table 8-8 or 8-8.1 contain testing and troubleshooting information useful in isolating a tape reader     malfunction. 8-9. PADS Test Set Self-Test Procedure.  The PADS test set self-test procedure is contained in table 8-6 or 8-6.1 and  is  arranged  in  three  columns.  The  first  column contains the test operation procedures to be performed, The second column contains the normal indication to be observed when the procedure has been performed. The third column contains the corrective action to be taken if the normal indication is not obtained. When performing corrective actions, see the SPU schematic diagram (figure FO-18) and wire lists (tables 8-1 and 8-2) to determine where to make voltage measurements. See the SPU parts location diagram (figure 8-1) and SPU  exploded  view  (figure  8-6)  for  location  parts. Whenever   a   corrective   action   has   been   taken,   the complete  self-test  procedure  must  be  repeated.  The self-test procedure must be followed in the order given. a. Test Equipment and Materials. The only equip- ment required is the self-test tape 877417-1. b. Test  Connections  and  Conditions.  Connect  cable W201 as shown in figure 8-2. c. Procedure. Perform self-test in table 8-6 or 8-6.1. accordance  with The tape used in testing of the PADS test set is electrically conductive. DEATH OR SERIOUS INJURY, as well as damage to 8-10. the tape may result if the tape is allowed to come into contact with 115 VAC. N O T E The PADS test set self-test procedure is semiautomatic.  At  various  times  through- out the test, different SPU indicators light and  extinguish  under  the  self-test  tape control. A failure is indicated only by the FAILURE/ACTION  indicator  malfunc- tion  code  (table  8-7)  or  incorrect  SPU response as noted in the procedure’s nor- mal  indication  column.  Make  sure  that tape reels are not deformed and that tape runs smoothly through tape reader head. Tape Reader Testing and Troubleshooting.  When the PADS self-test procedure has indicated that the tape reader has a malfunction, some initial checks should be made. N O TE Steps a and b apply to tape reader, part no. 877406-1 only. a. Check all external controls, switches, and indica- tors and make certain that all plug-in circuit cards are properly seated. Check to ensure that the external ac- power source is normal and that the + 28V and + 5V power supply output voltages are normal. Check that all input and output connections are secure. b. As an aid for checking waveforms and voltage, an extender card is furnished with the tape reader. The extender  card  allows  a  plug-in  circuit  card  to  be  ex- tended  above  the  normal  card  checked  at  the  card connector. NOTE Step  c  applies  to  tape  reader,  part  no. 877406-2 only. c. Check all external controls, switches, and indica- tors. Check to ensure that the external at-power source is normal and that the power supply output voltages are normal.  Check  that  all  input  and  output  connections are  secure. Change 1 8-45