TM5-6115-593-34 NAVFAC P-8-631-34 TO-35C2-3-463-2 CHAPTER 4 MAINTENANCE OF AC-DC CONTROL BOX ASSEMBLY Section I.  ENCLOSURE COMPONENTS 4-1.  FUEL TRANSFER PUMP RELAY K20. a.    Replacement.    (See  figure  4-1.)  The  fuel  transfer pump relay K20, (33, figure 4-1) is mounted on the right side   wall   of   the   AC-DC   control   box   assembly.      It   is removed as follows: WARNING BEFORE STARTING ANY MAINTENANCE    PROCEDURE,    SET MAINTENANCE   LOCKOUT   SWITCH TO LOCKOUT. DISCONNECT NEGATIVE CABLE FROM BATTERIES.      REMOVE   EXTERNAL POWER BY OPENING CB101 (EXTERNAL POWER CIRCUIT BREAKER)     AND     DISCONNECTING POWER CABLE FROM RECEPTACLE J101 (120V RECEPTABLE). (1) Open  door  of  AC-DC  control  box  assembly to gain access. (2) Remove   and   tag   wires   connected   to   the relay. (3) Remove   two   screws   (31)   and   nuts   (32). Remove relay (33). (4) Install  relay  (33)  by  mounting  it  to  the  side wall  of  the  enclosure  with  two  screws  (31) and nuts (32). (5) Connect wires and remove tags. a.  Testing (1) Connect  24V  DC  to  the  small  terminals  on the  contactor  in  series  with  a  SPST  switch as shown in figure 4-2. (2) Connect ohmmeter (Rx1) scale to the larger terminals of the contactor. (3) Close  the  SPST  switch.    Ohmmeter  should show continuity. (4) Open the SPST switch.  Connect ohmmeter to the smaller terminals.  Meter should read approximately 60 ohms. 4-2.  TERMINAL BOARD. 4-3.  REPLACEMENET.  The six terminal boards (26 and 30, figure 4-1) are mounted on the right side wall of the enclosure (75).  Replace as follows: a.   Removal.  Tag and remove leads.  Remove each terminal board (26 and 30) by removing two screws (24 or 28) and nuts (25 or 29). NOTE Diode  (28)  may  also  be  tagged  and disconnected    from    terminal    board (30) at this time. b.   Replacement.    Replace  terminal  board  (26  or  30) on the enclosure side wall by attaching two screws (24) and nuts (25).  Install diode (28) on terminal board (30) and remove tags. 4-4.  RESISTOR R116.    Resistor  R116  (38,  figure  4-1) is located on the right side wall of the enclosure (75). a.    Test.    Disconnect  either  lead  from  resistor  (38). With an ohmmeter (set Rx1 scale) measure resistance. It should be 5 ohms 1 ohm.  If not, replace. b.  Replacement. (1) Remove   two   nuts   (35,   figure   4-1)   which secure resistor lugs (36) to the standoff (37). Then remove resistor (38) from clip (41) and separate lugs (36) from lead 4-1