TM 1-1510-223-10 Change 3          8-9 b.   VHF navigation receivers (#1 and #2) — Test as follows: (1)   VOR self test/marker beacon test: (a) Tuning knob (NAV control unit) — Select a VOR frequency. (b) VOR/localizer   push-button   se- lector switch (display controller) — Select VOR 1 or VOR 2. (c) Single   needle   bearing   pointer source  selector  switch  (display controller) — VOR 1. (d) Double  needle  bearing  pointer source  selector  switch  (display controller) — VOR 2. (e) Course  knob  (EHSI)  —  Rotate until pointer indicates 0 degrees. (f) TEST  button  (NAV  control  unit) —   Depress.   Normal   test   will show  dashes  in  the  active  win- dow and 00 in the preset window. A fault will show DIAG in active display and a two digit fault code in the preset display. (g) NAV  flag  on  the  EHSI  —  Will come  into  view.  After  two  sec- onds, the flag will go out of view, the  EHSI  course  deviation  bar will  center,  and  a  TO  indication will appear. The bearing pointers will indicate a 0 magnetic bear- ing. The VIR-32 will return to nor- mal after 15 seconds. (h) EHSI — Check for three marker beacon indications (I, O, M illumi- nates) and listen for a 30 Hz tone on B audio channel of intercom box. (2)   ILS self test (NAV 1 and NAV 2): (a) Tuning knobs (NAV control unit) — Select a localizer frequency. (b) TEST  switch  (NAV  control  unit) — Depress. (c) NAV  and  GS  flags  on  EHSI  — Will come into view. After 3 sec- onds, the flags will go out of view, the  EHSI  course  deviation  bar will deflect 2/3 full scale, and the glideslope   pointer   will   deflect 1-1/4 dot right and down on the glideslope and localizer pointer. (d) VIR-32  —  Will  return  to  normal after 15 seconds. (3)   ADF receiver test: (a) Power and mode switch — ADF. (b) Tuning  knobs  (control  head)  — Tune a nearby NDB, compass lo- cator, or broadcast station. (c) EFIS display controller — Select ADF   on   single   needle   pointer bearing source selector switch. (d) TEST switch — Depress. Bear- ing pointer will rotate 90 degrees from   previous   indication.   Re- lease   TEST   switch   and   verify bearing  pointer  returns  to  pre- vious indications. (4)   TACAN/DME indicator system — Will conduct a self-test for 3 seconds after power-up. After 3 seconds, check for SELF  TEST  PASS  or  SELF  TEST FAIL (with a fail message number). (5)   Transponder (APX-100): (a) Mode selector — STBY. (b) Warm-up — Allow two minutes. (c) Mode 1 and mode 3/A codes — Set. (d) Lamp indicators — Press to test. (e) Antenna switch — Select to TOP. (f) Mode selector — NORM. (g) Modes 1, 2, 3/A and C — Hold to TEST and observe GO light. (h) Antenna  switch  —  Select  BOT and repeat step (g).