TM 1-1510-225-10 3B-181 d.   The color of the fourth target band (65 to 75 nm) is red e.   The two red target bands flash on and  off  approximately  once  each second. 5.   Momentarily press  WX/C  push  button and slide   TGT   ALRT  control  to   ON.   Verify  that  the  letter  T  in  a  red  box appears in the target alert field. 6.   Press  TEST push button and observe that   when   the   test   pattern   display crosses     the     centerline,     the     T     is replaced    by    a    flashing    TGT    label.   Slide   TGT   ALRT   control   to   OFF  to disable the function. 7.   Verify that 100 (nm) is displayed in the upper  right-hand  corner  and  that  the first four range marks are labeled with the correct numerics. 8.   Slide  AZ MK control to  ON  and  verify that  azimuth  marks  displayed   in cyan at 30° intervals.  Slide   AZ MK control to OFF to remove azimuth marks. 9.   Momentarily press  WX/C  push  button to   erase   display,   then   press   TEST push    button.        After    approximately 2 seconds,    momentarily    press    FRZ and    verify    that    the    1    2    3    display beneath  the  color  bar  is  replaced  by flashing FRZ label.  Verify that only a portion of the test pattern is displayed and    there    is    no    further    updating.   Momentarily  press   FRZ  push  button and    verify    that    the    display    begins updating  starting  at  the  current  scan position. 10.   Press 10 (nm) range push button and verify that the test pattern is momentarily blanked and the restored to the previous display. 11.   Momentarily press  WX/C  push  button and   verity   that   WX   appears   in   the Mode   field   and   10   appears   as   the selected  range.    Verify  correct  range numerics. 12.   Press    each    range    push    button    in succession (25 / 50 / 100 / 200 / 300) and verify that range numerics change appropriately with each selection. 13.   Momentarily press  WX/C  push  button and verify that CYC is displayed in the Mode field. 14.   Rotate GAIN    control     just     out     of PRESET and verify that 1 2 3 remains in the auxiliary field. 15.   Momentarily press  WX/C  push  button and verify that WX is displayed in the mode field and that VAR replaces 1 2 3 in auxiliary field. 16.   Momentarily  press   MAP  push  button and verify that MAP is displayed in the Mode field.  Verify that the color of the range   marks   and   alphanumerics   is green. 17.   Momentarily press  STBY  push button to    return    radar    to    non-transmitting state. Return GAIN     control     to PRESET. (4)   Fault     Displays.          Display     colors     are continuously  monitored  by  the  color  bar  and  1  2  3 legend in the auxiliary field.  If a fault causes a change to unfamiliar colors, the severity level denoted by the faulty color(s) is directly coded by the 1 2 3 legend. Other  circuits  continuously  monitor  performance and    loading    of    system    power    supplies.        A    fault resulting  in  power  supply  operation  outside  of  preset limits   will   cause   the   system   to   shut   down   and   the display   will   be   blank.      Should   this   occur,   use   the following procedure to recycle the system: 1.   Rotate INT / OFF control to OFF. 2.   Verify that aircraft radar circuit breaker is on. 3.   After a few seconds, rotate  INT / OFF control  to  mid-point  and  press   TEST push button. If  the  fault  was  of  transient  nature,  the  system may operate satisfactorily. (5)   Ground     Mapping.          Ground     mapping operation   is   selected   by   pressing   the    MAP   push button.    Turn  the   TILT  control  down  until  the  desired amount of terrain is displayed.  The degree of downtilt will  depend  upon  the  type  of  terrain,  aircraft  altitude, and selected range. For  the  low  ranges  (10,  25,  and  50  nm),  the transmitter  pulse  width  is  narrowed  and  the  receiver