Comtech EF Data SMS-758 - Manual (Page 116)

Maintenance SMS-758 Modem Protection Switch
5–4 MN/SMS758 Rev. 3
5.2.2 Demodulator Operation
Faults Procedures
BK-UP FAULT DMD X
(DOF_BU_OP_FLT_x) If no M:N faults exist:
Verify that the switch is in AUTO mode.
Verify that a backup demodulator is available to backup
all of the faulted prime demodulators.
Verify that the data cable between the switch and the
modem is connected to the correct connectors.
Verify that the IF cable between the switch demodulator
output and the modem IF input is connected to the
correct connectors.
If an M:N fault exists:
Check M:N faults for communication, configuration, and
compatibility faults.
ALL DMDS D/L X FAULTED
(DL_FLT_y) Verify that the downlink assignments for the demodulator are
programmed in the modem configuration and properly
connected behind the patch panel.
Verify that the IF cables between the switch demodulator
outputs and the modem IF inputs are connected to the correct
connectors.
Verify that the IF cables between the down converter
equipment and the switch downlink inputs are connected to
the correct connectors.
If there are faulted primes that are not backed up, or the
downlink signal is interrupted, the demodulator operation fault
display will remain ON.