Nautel NX15, Troubleshooting Manual

Page: 29 / 274

NX25/NX15 Troubleshooting Manual Responding to alarms
Issue 5.0 2016-05-06 Page 1-21
Exciter A/B: No Carrier
Sync Signal Present This alarm will occur when the transmitter’s Sync Source is set to
GPS Sync Card or Combiner and the 10 MHz or 1 kHz
synchronization signal is either not present or out of specification.
If the Sync Source is
set to Combiner, this alarm will cause the
transmitter to be
inhibited, otherwise this alarm is displayed for
information only.
If the transmitter’s Sync Source is set to GPS
Sync Card, check the connection between the GPS sync PWB
and the control/interface PWB. If the connection is OK, replace
the GPS sync PWB
(see “GPS Sync PWB replacement” on
page 1-61 ). If the alarm persists, replace the associated digital AM
exciter PWB (see “Digital AM exciter PWB replacement” on
page 1-55 ) or the control/interface PWB (see “Control/interface
PWB replacement” on page 1-60 ). If the transmitter’s Sync
Source is set to Combiner, check the connection between the
combiner and the control/interface PWB. If the connection looks
OK, troubleshoot the combiner’s synchronization signal source.
Exciter A/B: No External
10 MHz This alarm indicates the transmitter is set to run on an external 10
MHz source, but the exciter has determined the frequency of the
external source to be outside of the range 9.9 MHz to 10.1 MHz.
This will cause the exciter to revert to using its internal 10 MHz
reference until it determines the external 10 MHz is in range. This
may also cause an exciter changeover if a backup exciter is
installed and automatic changeover is enabled. Check the
integrity and signal level of the external 10 MHz source. If the
external source is acceptable and the alarm persists, replace the
associated digital AM exciter PWB (see
“Digital AM exciter PWB
replacement” on page 1-55 ).
Exciter A/B: No IBOC
Data This alarm indicates there is no modulation data being provided
by the embedded Exgine when the transmitter is running in an
IBOC mode of operation. This alarm will trigger the Digital Input
Loss alarm. Verify the transmitter is operating in the intended
mode. Verify the embedded Exgine is connected to the control/
interface PWB and the wiring connections are intact. Verify the
Exporter is connected to the Exgine and the Exgine is receiving
data from the Exporter. If the alarm persists, replace the
associated digital AM exciter PWB (see
“Digital AM exciter PWB
replacement” on page 1-55 ) or the Exgine PWB (see “Exgine
PWB replacement” on page 1-61 ).
Alarm (with Prefix) Description and Troubleshooting Action