Comtech EF Data SDM-300A - Manual (Page 353)

SDM-300A Satellite Modem Revision 6
Troubleshooting MN/SDM300A.IOM
18–17
Fault/Alarm Possible Problem and Action
DEMUX_LOCK Demultiplexer synchronization lock fault. This fault means that the demultiplexer is unable to maintain
valid frame and multiframe alignment.
The usual cause is invalid or absent receive data. This is a major (prompt) alarm. The alarm will cause
insertion of receive AIS (all 1s) and the switch-over will be attempted. This fault is to be sent as a
backward alarm to the distant end. This fault will occur when no carrier is present, but will probably
never occur with a correct signal.
RX 2047 LOCK RX 2047 lock alarm.
Indicates the RX 2047 data test pattern is not being received by the decoder. The alarm probably
indicates the transmitter is not set correctly.
BUFFER FULL Buffer full alarm.
Indicates the buffer is < 10% or > 90% full.
RX INSERT Insert interface hardware fault (D&I only).
The typical cause of this fault is the insert phase-locked loop is not locked, or some other insert
interface hardware has malfunctioned. Contact the Comtech EF Data Customer Support Department.
18.3.3.5 Common Equipment Faults
Fault/Alarm Possible Problem and Action
BATTERY/CLOCK M&C battery voltage or clock fault.
Indicates a low voltage in the memory battery. Typically, this fault will be active when a modem has been hard
reset or the firmware has been changed. When a hard reset has been executed or the firmware has been
changed, this fault will typically be active when the modem is first turned on.
-12 VOLT SUPPLY -12V power supply fault.
Indicates a high or low voltage condition. Level is
± 5%. Check for a short on the -12V line from the power supply
or on any of the plug-in boards.
+12 VOLT SUPPLY +12 VDC power supply fault. Use the same procedure as with -12V fault.
+5 VOLT SUPPLY +5V power supply fault.
Use the same procedure as with a -12V fault. The +5V supply requires a minimum load of 1A.
CONTROLLER Controller fault.
Indicates a loss of power in the M&C card. Typically indicates the controller has gone through a power on/off
cycle.
INTERFACE Interface module fault.
Indicates a problem in programming the interface card.