ARMY  TM  5-6675-238-14 MARINE CORPS TM 08839A-14/1 8-11. Tape Reader Testing and Troubleshooting Proce- dure. a.    General. Testing and troubleshooting of the tape reader consists of performing the procedures in table 8-8  or  8-8.1.  Table  8-8  uses  tape  reader,  part  no. 877406-1,  and  table  8-8.1  uses  tape  reader,  part  no. 877406-2. The procedure 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, As an aid in performing the test proce- dure,  see  the  tape  reader  schematic  contained  in  figure FO-19 or FO-20. See figure 8-3 for location of tape reader test points and figure 8-4 for location of plug-in circuit card adjustments. Figures 8-3 and 8-4 apply to tape  reader,  part  no.  877406-1,  See  the  tape  reader exploded view (figure 8-10 or 8-10.1) for location of parts. b. Test  Equipment  and  Materials  (Tape  Reader, Part No. 877406-1). (1) (2) (3) (4) (5) (6) Signal  processor  unit Digital Voltmeter AN/GSM-64B Oscilloscope AN/USM-281A or AN/USM-273 Self-test  tape Take-up reel Multimeter  AN/USM-223 c.  Test  Equipment  and  Materials  (Tape  Reader, Part  No.  877406-2). (1) Signal processor unit d. Test Connection and Conditions (Tape Reader, Part  No.  877406-1). When  working  on  the  tape  reader,  re- move from case and use extreme care to avoid damage to components and cables. (1) Remove tape reader from instrument case (3, figure 8-10, sheet 1) by removing 20 screws (1) and washers (2). (2) Connect cable W201 as shown in figure 8-2. (3) Connect cable W203 as shown in figure  8-2. e.  Test  Connections  and  Conditions  (Tape  Reader, Part No. 877406-2). (1) Remove tape reader from instrument case (3, fire 8-10.1, sheet 1) by removing 20 screws (l) and washers (2). (2) Connect cable W201 as shown in figure 8-2. (3) Connect cable W203 as shown in figure 8-2. f.   Procedure (Tape Reader, Part No. 8774M-1). Perform  tape  reader  testing  and  troubleshooting  in accordance with table 8-8. NOTE Except for SPOOLING switch S1 (DIS- ABLE/ENABLE)   located   on   the   tape reader  (unit  23),  all  other  switches  are located on the SPU (unit 20). The  tape  reader  contains  115  VAC;  be especially careful when working around F2  and  T1.  DEATH  OR  SERIOUS  IN- JURY may result from contact with 115 VAC. B1 is extremely hot to the touch. The   tape   used   in   testing   of   the   tape reader is electrically conductive. DEATH OR SERIOUS INJURY, as well as damage to the tape may result if the tape is al- lowed  to  come  into  contact  with  115 VAC. NOTE Check that the tape reader head is clean before  proceeding  with  procedures  in  ta- ble 8-8. If any component is replaced during test- ing, table 8-8 tests 1, 2, and 5 must be performed. Unless otherwise indicated, the replace- ment  of  any  tape  reader  component  re- quires that testing be restarted. Make  sure  that  tape  reels  are  not  de- formed and that the tape runs smoothly through tape reader head. g. Procedure (Tape Reader, Part No. 877406-2). Perform  tape  reader  testing  and  troubleshooting  in accordance with table 8-8.1. The  tape especially reader contains 115 VAC; be careful when working around 8-64 Change 1