MNC-0400-048
8 of 14
Revision B
Operation, TWTA ODU Amplifier
Table 1TWTA Fault Log Troubleshooting
Fault Log
Entry
Description
Possible Cause of
Fault
Action Needed to
Clear Fault
Cbl ILOK
Cable Interlock Fault
A cable other than
the M&C cable has
come loose.
Check all cables for
proper connection.
CstPwr A
Constant Power mode
suspended.
RF input power has
suddenly dropped.
Check input power
level. Look for loose
or disconnected RF
cable.
Cvr ILOK
Cover Interlock Fault
The top cover of a
rack unit has been
removed.
Re-install top cover.
DCV LOW Low DC Voltage Alarm -
voltage on computer board.
The DC bias voltage
to the computer
module has
dropped below the
minimum level.
Call customer
service.
Ext ILOK
External Interlock Fault
The M&C connector
has been
disconnected, or
there is no jumper in
the M&C cable to
close the interlock.
Check for
disconnected cable
or a cable with no
interlock jumper.
See manual with
addendum, ODU
External Interlock,
MNC-0000-026,
Table 1.
Fan Lock
Fan Fault
Fan is not operating
correctly
Clean fan and filter.
Ensure fan spins
freely.
FW CHSUM Firmware Checksum Alarm
The program
memory has
changed, or
program memory
has failed.
Call customer
service.
HEATER F Heater Fault
Heater Power
Supply, or failed
TWT filament.
Call customer
service.
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