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67
(Rev. 8/04)
®
The “Check CDBR Cabling” handset text message
as shown below will be displayed when the ARTU
detects a synchronization problem on the LAN bus
between the ARTU and the LAN repeaters. Typically
this fault condition occurs because of cabling prob-
lems. The most common cause of this problem is
incorrect wiring or pinched wiring in the connector
backshell. The ARTU and LAN repeaters can also be
damaged if a LAN repeater is inadvertently connected
up backwards, resulting in the same type of fault.
LAN repeaters can be damaged if no cable strain relief is provided in
the installation and may cause intermittent operation or latent faults.
See Section 9.1.8 and 9.2.1 in the Magnastar Installation Manual for
MMT troubleshooting designed to isolate and correct intermittent
faults.
The “Temporary Service Disruption” handset text
message is generated by the handset itself and does
not originate from the ARTU as do all other handset
messages. This message is generated by the handset if
power and ground are present but the handset is miss-
ing the clock, sync or data signals. The message may
also appear if the data to the handset is corrupted. If
this message appears, verify that the ARTU has not
detected a fault condition or is running power-up Built-In Test (BIT).
This can be done by viewing the fault (red) light on the front of the
ARTU. If the ARTU fault light is illuminated then a fault has been
detected or is running power-up BIT. Power-up BIT should not take
longer than five minutes to complete. If after enough time has passed
to allow power-up BIT to complete then the handset text message
would be displayed because of a fault with the ARTU. If the
temporary service disruption handset text message is present and
the ARTU fault light is not present, then check the handset and
CDBR cabling in the aircraft.
Check
CDBR
Cabling
Handset
Operation May
Be Intermittent
Temporary
Service
Disruption