Nautel NX50 Programming manual

NX50 Transmitter
Troubleshooting Manual
Document:NHB-NX50-TRB
Issue: 6.0 2019-04-01
Status: Standard

Nautel Limited
10089 Peggy’s Cove Road
Hackett’s Cove, NS Canada B3Z 3J4
Phone: [phone] or
Toll Free: +1.877.6NAUTEL (6628835) (Canada & USA only)
Fax: [phone]
Nautel Inc.
201 Target Industrial Circle
Bangor, Maine USA 04401
Phone: [phone]
Fax: [phone]
Customer Service (24 hour support)
+1.877.628.8353 (Canada & USA only)
+1.902.823.5100 (International)
Email: [email protected]
Web: www.nautel.com
The comparisons and other information provided in this
document have been prepared in good faith based on publicly
available information. The reader is encouraged to consult the
respective manufacturer's most recent published data for
verification.
© Copyright 2019 NAUTEL. All rights reserved.

NX50 Troubleshooting Manual Table of contents
Page v
Contents
Release control record ix
Responding to alarms 1-1
Corrective maintenance 1-1
Electrostatic protection 1-3
Identifying an alarm 1-5
Troubleshooting an alarm 1-7
Accessing the Inside of the Transmitter 1-42
Troubleshooting Tips 1-43
Removing and reinstalling RF power modules 1-51
Troubleshooting RF power modules 1-56
Control/interface PWB replacement 1-64
Remote interface PWB replacement 1-66
Digital AM exciter PWB replacement 1-66
GPS Sync PWB replacement 1-71
USB Audio Interface PWB replacement 1-71
Exgine PWB replacement 1-72
PDM Drive Distribution PWB replacement 1-73
RF drive distribution PWB replacement 1-74
Rack Interface PWB replacement 1-76
SCR Rectifier Inspection/Replacement 1-78
Rectifier Fan Inspection/Replacement 1-80
Low Voltage Power Supply Replacement 1-81
RF Power Module Fan Tray replacement 1-84
RF Power Module Fan Tray Cooling Fan replacement 1-85
Touchscreen Monitor Replacement 1-86
Single Board Computer (SBC) Replacement 1-87
Arc Detector UV Sensor Replacement 1-90

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RF Voltage Probe Replacement 1-93
RF Current Probe Replacement 1-95
Parts Lists 2-1
Parts information 2-1
Family tree 2-1
How to locate information about a specific part 2-1
Column content 2-2
Common abbreviations/acronyms 2-4
Wiring/connector lists 3-1
Wiring lists provided 3-1
Wiring lists not provided 3-1
Connector mating information 3-1
Wire colours 3-1
Printed wiring board patterns 3-1
Reading Electrical Schematics 4-1
Component values 4-1
Graphic symbols 4-1
Logic symbols 4-1
Reference designations 4-1
Unique symbols 4-2
Identifying schematic diagrams 4-2
Structure of schematics 4-2
Locating schematic diagram(s) for a functional block 4-3
Locating a part or assembly on a schematic 4-3

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Mechanical Drawings 5-1
Identifying mechanical drawings 5-1
Content of mechanical drawings 5-1
List of terms 6-1

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NX50 Troubleshooting Manual
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Release control record
Issue Date Reason
6.0 2019-04-01 Supports release 6 of hardware (NARA53E) and
software version NX SW 4.7 or higher.

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Section 1: Responding to alarms
This section provides instructions you need when performing troubleshooting on the NX50
transmitter. This section includes the following topics:
•Corrective maintenance
•Electrostatic protection - see page 1-3
•Identifying an alarm - see page 1-5
•Troubleshooting an alarm - see page 1-7
•Accessing the Inside of the Transmitter - see page 1-42
•Troubleshooting RF power modules - see page 1-56
•OtherModule Replacement Procedures - see page 1-41
If none of the procedures and alarms described in this section address your problem, contact
Nautel for assistance.
Corrective maintenance
Corrective maintenance procedures consist of identifying and correcting defects or deficiencies
that arise during transmitter operation. Local and/or remote alarm signals are generated when
a malfunction occurs. If an alarm condition is caused by a malfunction in the RF power stage,
the transmitter may maintain operation at a reduced RF output level. The nature of the fault –
and station policy – will dictate whether an immediate maintenance response is necessary.
Fault analysis and rectification may be conducted from three different levels, with a different
technical competence level required for each: on-air troubleshooting, remote or local, and off-
air troubleshooting.
CAUTION:
The transmitter contains many solid state devices that may be damaged if
subjected to excessive heat or high voltage transients. Every effort must be taken
to ensure that circuits are not overdriven or disconnected from their loads while
turned on.

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On-air troubleshooting
On-air troubleshooting can be performed from a remote location, or locally at the transmitter
site.
Remote troubleshooting
Remote on-air troubleshooting consists of monitoring the transmitter's radiated signal using an
on-air monitor or via a LAN connection, and observing the status of each remote fault alarm
indicator. Information obtained from these sources should enable an operator to decide
whether an alarm response may be deferred to a more convenient time, an immediate
corrective action must be taken, or if a standby transmitter must be enabled (if one is
available). It is recommended that the significance of remote indications, and the appropriate
responses, be incorporated into a station's standard operating procedures. Refer to “Identifying
an alarm” on page 1-5 to determine the remedial action required for a given fault.
Local troubleshooting
Local on-air troubleshooting consists of monitoring the transmitter's integral meters and fault
alarm indicators. Analysis of this data will normally identify the type of fault, and in most
cases will determine what corrective action must be taken. Refer to “Identifying an alarm” on
page 1-5 to determine the remedial action required for a given fault.
The power amplifier stage contains an integral modular reserve (IMR) feature. This feature
permits the transmitter to operate at a reduced RF output level when a malfunction occurs in
one of its power modules. Station operating procedures will dictate whether a reduced RF
output level is acceptable. When a reduced RF output level can be tolerated, replacement of the
defective RF power module may be deferred to a convenient time. A defective RF power
module may be removed from the transmitter for servicing, while the transmitter is operating,
provided that the conditions in the removal instructions detailed in “Removing an RF power
module” on page 1-51 are met.
Off-air troubleshooting
Off-air troubleshooting must be performed when the replacement of a defective RF power
amplifier module, or routine on-air calibration adjustments, will not restore operation.
WARNING:
Failure to follow the RF power module removal instructions may
result in injury to the operator and serious physical damage to the RF
power module and transmitter.

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It is recommended that the transmitter’s output be connected to a precision 50 resistive
dummy load (rated for 1.5 times the rated transmitter carrier power) before starting off-air
troubleshooting procedures. If an appropriate dummy load is not available, troubleshooting
for a majority of faults can be performed with the RF power stage turned off. The transmitter
may remain connected to its antenna system for these procedures.
Electrostatic protection
The transmitter's assemblies contain semiconductor devices that are susceptible to damage
from electrostatic discharge. The following precautions must be observed when handling an
assembly which contains these devices.
Electrical discharging of personnel
Personnel should be electrically discharged by a suitable grounding system (e.g., anti-static
mats, grounding straps) when removing an assembly from the transmitter, and while handling
the assembly for maintenance procedures.
Handling/Storage
An assembly should be placed in an anti-static bag when it is not installed in a host transmitter,
or when it is not undergoing maintenance. Electronic components should be stored in anti-
static materials.
Tools/Test equipment
Testing and maintenance equipment – including soldering and unsoldering tools – should be
suitable for contact with static sensitive semiconductor devices.
NOTE:
Reduce the RF output level to a minimal value when troubleshooting faults in
the power amplifier stage while the transmitter’s RF output is connected to the
antenna system.
CAUTION:
Electrostatic energy is produced when two insulating materials are rubbed
together. A person wearing rubber-soled shoes, walking across a nylon carpet or a
waxed floor, can generate an extremely large electrostatic charge. This effect is
magnified during periods of low humidity. Semiconductor devices such as
integrated circuits, field-effect transistors, thyristors and Schottky diodes may be
damaged by this high voltage unless adequate precautions are taken.

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Stress current protection
Every precaution should be taken to ensure the static sensitive semiconductor devices are
protected from unnecessary stress current. This is achieved by ensuring that current is not
flowing when an electrical connection is broken, and that voltages are not present on external
control/monitoring circuits when they are connected.

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Identifying an alarm
You can identify an alarm by viewing the Transmitter Status page (Figure 1.1), either locally
on the front panel of the transmitter, or remotely through an ethernet connection. After
successfully identifying an alarm, attempt to determine the cause of the alarm and correct it
(see “Troubleshooting an alarm” on page 1-7). The colour of the Status button at the bottom of
the AUI indicates the severity of the highest offending alarm. The button can display green,
amber or red. When the Status button is:
• Green - transmitter is on, with no known faults that would affect the normal operation
of the transmitter.
• Amber - a fault is present that affects the normal operation of the transmitter and may
cause a reduction n RF power, but the transmitter is still producing RF power.
• Red - a fault is present and the transmitter is not producing power.
Figure 1.1: Transmitter Status Page

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Click the Status button to view the Transmitter Status page (Figure 1.1 on page 1-5), which
displays a list of active alarms. Alarms are listed by their origin (Device column), then by name
(Alarm column), and then by severity (Level column).
1. The Device column displays the sub-system origin of the alarm. The sub-systems that
can be displayed are:
• Controller: All Alarms in this sub-system apply to the controller.
• Exciter A or B: All Alarms in this sub-system apply to an exciter (A or B)
• Rack #: All Alarms in this sub-system apply to a rack (cabinet) (Rack 1)
• Module #: All Alarms in this sub-system apply to a specific RF power module (1
through 20)
• Exgine: For systems with Exgine installed, all alarms in this sub-system apply to
the Exgine.
2. The Alarm column displays the alarm name. Use this name as a cross-reference during
troubleshooting (see “Troubleshooting Alarms” on page 1-8).
3. The Level column displays a symbol that indicates the severity of the alarms, as
follows:
• One Yellow ! - low severity, normal operation of transmitter not affected
• One Orange ! - medium severity, normal operation of transmitter affected, RF
output may be reduced
• Two Red !! - high severity, RF output is inhibited

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Troubleshooting an alarm
Troubleshoot an alarm as follows:
1. Attempt to clear any latching alarms by pressing the Reset button on the bottom
banner of the AUI. If the alarm persists, it will not be cleared from the display.
2. Locate the alarm name in Table 1.1 on page 1-8 (sorted alphanumerically for each sub-
system) to determine the cause of the alarm and perform any recommended procedures
in the Description and Troubleshooting Action column. This may also lead to
replacing a suspect PWB, power supply or fan, as detailed in Table 1.3 on page 1-41.
3. Refer also to Table 1.2 on page 1-36 for Summary alarms that can occur - when
properly configured - as remotely monitored outputs.
4. If troubleshooting and subsequent replacement of a suspect PWB or module causes the
alarm to disappear, the alarm has been successfully cleared. If the fault condition does
not clear contact Nautel Customer Service for assistance.
NOTE:
Before undertaking any troubleshooting, record all AUI meter readings and note
if any other alarms are displayed on the Transmitter Status page. Record all
alarms. The most convenient way to do this is by using a web browser over a
LAN connection to copy the Critical Parameters. Go to Menu, User Settings and
select Critical Parameters. Select Capture Meters button followed by Copy Meters
button and paste into a spreadsheet or word file for later viewing if necessary.
Capture alarms in the same manner - Capture Alarms followed by Copy Alarms
and paste into file.
NOTE:
Table 1.2 lists the Summary alarms that can be configured for remote
monitoring through the local or remote AUI’s Remote I/O -> Remote Outputs
menu (see the “Operating the Transmitter” section of the Operations &
Maintenance Manual for configuration details). Each Summary alarm can be
triggered by any one alarm in a specific sub-set, as shown in Table 1.2. The
Description and Trigger Alarms column of Table 1.2 provides a brief description
of the summary alarm and a list of the triggering alarms. To determine the root
cause(s) of a Summary Alarm, check the local or remote AUI for an offending
trigger alarm and refer to its troubleshooting information for more details.

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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).

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Controller: Controller
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 1.4 V, which normally happens due to a loss of ac power.
If the controller is rebooting without losing ac power to the
transmitter, check for the presence of other alarms at the time of
the controller reset and follow the troubleshooting information for
those alarms. Otherwise, replace the control/interface PWB (see
“Control/interface PWB replacement” on page 1-64).
Controller: EEPROM
Failure: Config This alarm occurs when the transmitter is unable to read the following settings from EEPROM upon boot-up. The transmitter
will revert to its initial default settings, which may be different from
the values set before the transmitter was shipped. The alarm will
remain asserted until at least one of the settings are changed.
Affected settings are:
– Main Exciter (Defaults to A)
– Standby Exciter Installed (Defaults to Yes)
– Exciter Sync (Defaults to None)
– Active Max Power Lockout (Defaults to 1)
– RF Monitor Select (Defaults to forward power)
– Host Watchdog Enable (Defaults to OFF, should be turned
ON)
– Network Configuration
Configure the affected settings as desired. Cycle (turn off, then
on) ac power to the transmitter. If the alarm persists, replace the
battery on the control/interface PWB and retry the above steps. If
the alarm persists, replace the control/interface PWB (see
“Control/interface PWB replacement” on page 1-64).
Alarm (with Prefix) Description and Troubleshooting Action

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Controller: EEPROM
Failure: Thresholds This alarm occurs when the transmitter is unable to read its configuration for transmitter type and rack interface serial
numbers from EEPROM upon boot-up. The transmitter will revert
to its initial default settings, which may be different from the values
set before the transmitter was shipped. The alarm will remain
asserted until the setting is changed. Change the transmitter type
to the correct setting. Remove and re-apply the ac power to the
transmitter. If the alarm persists, replace the battery on the
control/interface PWB and retry the above steps. If the alarm
persists, replace the control/interface PWB (see “Control/interface
PWB replacement” on page 1-64).
Controller: EEPROM
Failure: Potentiometers This alarm occurs when the transmitter is unable to read its RF Symmetry Adjustment calibration from EEPROM upon boot-up.
The alarm will remain asserted until the RF Symmetry has been
re-calibrated. When this alarm occurs, the transmitter will load a
default level of exactly mid-scale for the symmetry adjustment
potentiometers. Set the RF Symmetry Adjust per the factory
configuration. Cycle (turn off, then on) ac power to the transmitter.
If the alarm persists, replace the battery on the control/interface
PWB and retry the above steps. If the alarm persists, replace the
control/interface PWB (see “Control/interface PWB replacement”
on page 1-64).
Controller: EEPROM
Failure: Remotes This alarm occurs when the transmitter is unable to read its remote I/O configuration from EEPROM upon boot-up. The
transmitter will revert to the initial default remote I/O settings and
the alarm will remain asserted until a new remote input/output is
configured. Reconfigure the remote I/O settings as desired. Cycle
(turn off, then on) ac power to the transmitter. If the alarm persists,
replace the battery on the control/interface PWB and re-try the
above steps. If the alarm persists, replace the control/interface
PWB (see “Control/interface PWB replacement” on page 1-64).
Controller: EEPROM
Failure: Schedule This alarm occurs when the transmitter is unable to read its schedule configuration from EEPROM upon boot-up. The
transmitter will establish a new, completely blank schedule. The
alarm will remain asserted until at least one new scheduled event
is created. Recreate the desired schedule settings. Cycle (turn off,
then on) ac power to the transmitter. If the alarm persists, replace
the battery on the control/interface PWB and retry the above
steps. If it still persists, replace the control/interface PWB (see
“Control/interface PWB replacement” on page 1-64).
Alarm (with Prefix) Description and Troubleshooting Action