
NX50 Troubleshooting Manual
Responding to alarms
Page 1-22
Issue 6.0 2019-04-01
Exciter A/B: No B+
Sample
This alarm indicates the exciter’s B+ voltage sample is below 40 V
for more than 10 seconds. If there is an associated Low B+
voltage alarm, follow the troubleshooting information for that
alarm. If there are no additional alarms and there is a second
exciter installed, switch exciters and check if the alarm is present
on the other exciter. If the alarm is present on the second exciter,
check the cabling between the B+ sampling point and the control/
interface PWB. If the connection is OK, replace the control/
interface PWB (see
“Control/interface PWB replacement” on
). If the alarm is not present on the second exciter, or
there is no second exciter in the transmitter, replace the digital AM
exciter PWB (see
“Digital AM exciter PWB replacement” on
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
If the alarm persists, replace the associated digital AM
exciter PWB
(see
“Digital AM exciter PWB replacement” on
) or the control/interface PWB (see
). 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
).
Alarm (with Prefix)
Description and Troubleshooting Action
Содержание NX50
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