(2)  
In an alternate configuration receiver No. 3 sends data to either the captain's or first officer's instruments dependent upon the position of the transfer switch(es) and relays.

 EFFECTIVITY

 AF 121, 122, 155-171,  CONFIG 3 174-190, 195-199;  01 Page 30 VM ALL  Sep 25/94

34-31-00
 VOR/ILS NAVIGATION SYSTEM - TROUBLE SHOOTING
____________________________________________
 1.  General_______
 A.  The following trouble shooting procedures are based on performance of the system operational test using VOR/ILS navigation system 1. Trouble shooting system 2 can be accomplished using the same procedures with the substitution of first officer for captain and RMI wide bearing pointer for RMI narrow bearing pointer. Trouble shooting alternate VOR/ILS receiver No. 3 can be accomplished by selecting the third receiver in place of receiver No. 1 or 2 and following the applicable procedures. The procedures are presented in tree-type format. The test steps (heavy-line boxes) are connected by shaded arrows to show the OK condition path. When all steps in the OK condition path check out, the system is operable
 B.  When a test step does not check out, follow the NOT OK line to the box containing the trouble symptom. Turn to the procedure indicated and continue to follow a single line by analyzing the results of each test step until the required corrective action is determined. Perform the specified corrective action; then repeat the step at which the failure was encountered.
 C.  All trouble shooting procedures are based on the assumption that wiring is OK and that electrical power is available. If the corrective action in the procedure does not correct the problem, check wiring using the wiring diagram.
 D.  The VOR/LOC antenna switches are fail safe units, which if faulty can cause weak VOR reception. If only one system reception is weak, swap antenna switches to see if the problem follows the switch. Also check the antenna switching logic. Check that the rf distribution system coaxial connectors are properly connected. Cross-threaded or loose connectors cause weak rf reception. Compare the VOR test signal levels required to pull the warning flags from view in the flight instruments. Also compare the localizer test signal levels required for flag retraction. Refer to 34-31-00, System Test.
 NOTE: Do not compare VOR vs LOC test signal levels.
____
 CAUTION: DO NOT ACTIVATE A "GLIDE SLOPE ANT TEST" SWITCH ON PANEL P2 IF
_______ A GLIDE SLOPE ANTENNA SWITCHING FAILURE HAS BEEN REPORTED (G/S-1 ANT, G/S-2 ANT OR G/S-3 ANT ANNUNCIATOR ON PANEL P2 ILLUMINATED). REFER TO 34-31-12, GLIDE SLOPE ANTENNA SYSTEM -TROUBLE SHOOTING, FOR THE PROPER FAULT ISOLATION PROCEDURE TO PREVENT POSSIBLE FURTHER DAMAGE TO AUTOPILOT ACCESSORY BOXES.
 2.  Prepare for Trouble Shooting
____________________________
 A.  Verify that all circuit breakers on the STANDBY BUS, ESS FLT INST BUS and FLT INST BUS NO. 2 on panel P7 and the MISC bus on panel P12 are closed.
 B.  Place AP/FD mode select panel switches and controls as follows: Course Transfer - DUAL NAV Mode Select - HDG All Others - OFF COURSE Counters - 000
 EFFECTIVITY
 AF 101-120, 123-154,  CONFIG 1 172-173, 191-194; GN ALL;  04 Page 101 LH ALL AND MD ALL  Sep 25/94

34-31-00
 C.  On XA ALL EXCEPT LH 011-030, 051-070 and 082-099, position power control knobs (VHF NAV control panels) to VOR/ILS.
 D.  Position captain's VOR/ILS transfer switch (Pl panel) to CAPT 1 F/O 2.
 E.  Position both VOR/ILS-INS switches (P10 panel) to VOR/ILS.
 F.  Place flight controller TURN knob in detent position.
 G.  Place STANDBY POWER switch (P4 panel) to NORMAL or OFF position.
 H.  Check that STANDBY IGNITION switch (P5 panel) is in NORM position.
 I.  Provide electrical power (Ref 24-22-00).
 EFFECTIVITY

 AF 101-120, 123-154,  CONFIG 1 172-173, 191-194; GN ALL;  04 Page 102 LH ALL AND MD ALL  Sep 25/94

34-31-00
Prepare system for troubleshooting as described in par. 2. Check that NAV source annunciator in captain's HSI indicates 1, that F/O's indicates 2 and that both HSI VOR/ILS - INS annunciators indicate VOR/ILS. IF -

NAV SOURCE ANNUNCIATION FAULTY - Troubleshoot instrument
NOT OK
switching circuits. (Refer to Wiring Diagram Manual, Radio Navigation Display Schematics.)
VOR/ILS - INS ANNUNCIATION FAULTY - Replace RAD/INS
NOT OK
transfer relay (AMM 34-31-06) or VOR/ILS - INS transfer switch (AMM 34-31-08) and perform specified test.
OK

NOT OK
OK FLAG DISPLAY FAULTY - Replace indicator in which flag did not drop (RMI: AMM 34-21-06, ADI: AMM 34-41-05, HSI: AMM 34-41-06) and perform specified test.
　
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