Nautel NX50, Troubleshooting Manual

Page: 18 / 205

NX50 Troubleshooting Manual Responding to alarms
Page 1-8 Issue 6.0 2019-04-01
Table 1.1: Troubleshooting Alarms
Alarm (with Prefix) Description and Troubleshooting Action
Controller: Audio Loss
Shutdown This alarm occurs if the modulation level is below the preset
threshold for the designated period of time set in the Audio Loss
settings of the current preset, and the desired action was set to
RF Inhibit. This will cause the transmitter to shut down its RF
output until the exciter determines that the modulation source has
returned. If this alarm is unexpected, check the audio inputs
specified in the preset and verify there is signal present.
Controller: Arc Shutback This alarm indicates the transmitter has entered a shutback (see
Shutback on page 3.1.10 of the Operations & Maintenance
Manual for a description of the shutback routine) due to one of the
rack controller’s arc detectors being activated. When this fault
occurs, the transmitter immediately inhibits PDM and the
transmitter's output power drops to 0 W. Once the fault clears the
transmitter will automatically recover, either to the power setpoint,
or to a reduced power as determined by the cutback routine (see
“
Cutback: ” on page 1-12
of the Operations & Maintenance Manual
for a description of the cutback routine). Visually inspect the inside
of the transmitter to locate the fault causing the arc detector to
trigger.
Controller: Brownout
Reset This alarm is only visible in the transmitter logs, and indicates the
controller was reset because its +5 V power supply voltage was
less than +4.3 V, but remained above +1.4 V, and then
subsequently recovered. This alarm should occur concurrently
with other alarms. Follow the troubleshooting information for the
associated alarms. If the alarm persists without the presence of
other alarms, replace the control/interface PWB
(see “Control/
interface PWB replacement” on page 1-64 ).
Controller: Combiner
Interlock Open This alarm will only occur if the transmitter is connected in a
combined system. The alarm indicates that the interlock signal
from the combiner is open. When this alarm occurs, the
transmitter immediately inhibits the PDM and the transmitter's
output power drops to 0 W. The transmitter will automatically
recover when the condition is cleared. Check the combiner for a
condition that may cause it to open the interlock to the transmitter.
If so, troubleshoot the cause of that condition. If not, inspect the
wiring between the combiner and the transmitter and verify there
is no damage. If the alarm persists, replace the control/interface
PWB
(see “Control/interface PWB replacement” on page 1-64 ).