2)  Re-install the remote electronics unit. To install it, do this task: Remote Electronics Unit (REU) Installation, AMM TASK 23-51-01-000-802.
3)  Re-install the VOR/marker beacon receiver. To install it, do this task: VOR/MKR
Receiver Installation, AMM TASK 34-51-01-400-801.
4)  Do this task: Marker Beacon System -System Test, AMM TASK 34-32-00-730-801.
5)  If the audio tone is normal, then you corrected the fault.
(e) If there is continuity, then do this step and continue:
1)  Re-install the VOR/marker beacon receiver. To install it, do this task: VOR/MKR Receiver Installation, AMM TASK 34-51-01-400-801.
(3) Replace the remote electronics unit, M1353. These are the tasks: Remote Electronics Unit (REU) Removal, AMM TASK 23-51-01-000-801, Remote Electronics Unit (REU) Installation, AMM TASK 23-51-01-000-802.
(a)
Do this task: Marker Beacon System -System Test, AMM TASK 34-32-00-730-801.

(b)
If the audio tone is normal, then you corrected the fault.

-------------------------END OF TASK ---------------------------
802. Indication And Audio Tone Problem -Fault Isolation
A.  Description
(1)  Indication does not show on the display when passing a marker, audio tone does not occur or is weak.
B.  Possible Causes
(1)  
Marker Beacon antenna and its coaxial cable.

(2)
VOR/marker beacon receiver, M1724.

(3)
Wiring.

(4)  
Remote electronics unit, M1353.

(5)
Display electronics unit (DEU), M1808 (No. 1) or M1809 (No. 2).

C.  Circuit Breakers
(1)  This is the primary circuit breaker related to the fault:
CAPT Electrical System Panel, P18-1
Row Col Number Name
A 1 C01374 RADIO NAVIGATION VOR/MKR BCN 1

D.  Related Data
(1)
(SSM 34-32-11).

(2)
(WDM 34-32-11).

E.  Initial Evaluation
(1)  Do this task: Marker Beacon System -System Test, AMM TASK 34-32-00-730-801.
EFFECTIVITY

34-32 TASKS 801-802
SIL ALL
Page 202 D633A103-SIL Feb 15/2009

(a)  
If the indication do not show on the display and the audio tone is weak, then do the Fault Isolation Procedure below.

(b)  
If the indications and the audio tone are normal, then there was an intermittent fault.

F.  Fault Isolation Procedure
(1)  
Do
this
task:Audio
Tone
Problem
-Fault
Isolation,
34-51
TASK
809

(a)  
If the indications do not show on the display and the audio tone does not occur or is weak, then continue.

(b)  
If the indications shows on the display and the audio tone is normal, then you corrected the fault.

(2)  
Do
this
task:
VOR/Marker
Beacon
Receiver
BITE
Procedure,
34-51
TASK
801.

(a)  If the VOR/Marker Beacon BITE test shows a fault, then go to the fault isolation task for the applicable maintenance message to correct the fault.
1)  Do this task: Marker Beacon System -System Test, AMM TASK 34-32-00-730-801.
a)  If the indications do not show on the display and the audio tone does not occur or is weak, then continue.
b)  If the indications shows on the display and the audio tone is normal, then you corrected the fault.
(b)  If the VOR/marker beacon BITE test does not show a fault, then continue.
(3)  Do this check of the wiring:
(a)  
Remove the remote electronics unit, M1353. To remove it, do this task: Remote Electronics Unit (REU) Removal, AMM TASK 23-51-01-000-801.

(b)  
Remove the VOR/marker beacon receiver, M1724. To remove it, do this task: VOR/MKR Receiver Removal, AMM TASK 34-51-01-000-801.
　
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