Nautel NX50, Troubleshooting Manual, Page: 66 / 205

NX50 Troubleshooting Manual Responding to alarms
Page 1-56 Issue 6.0 2019-04-01
Troubleshooting RF power modules
Maintenance philosophy
Recommended troubleshooting procedures for RF power modules are limited to “go” or “no-
go” resistance or diode measurements on the module’s power semi-conductors and replacement
procedures for these devices.
Special Tools and Test Equipment
The following test equipment and cables are required to troubleshoot an RF power module.
• A digital multimeter with resistance and diode settings.
• A torque screwdriver with a torque range of 0.0 to 2.3 N-m (0 - 20 in.-lbs). Required
for installing MOSFET attaching hardware.
• A soldering iron and desoldering tool.
• An NX50 spares kit (contains replacement semi-conductors).
Electrostatic Precautions
The RF power module contains semiconductor devices that are susceptible to damage from
electrostatic discharge. Be sure to follow the electrostatic precautions in “Electrostatic
protection” on page 1-3 at all times.
Preparation for Troubleshooting
1. Follow the procedure in “Removing an RF power module” on page 1-51 to remove the
RF power module from the transmitter.
2. Place the RF power module on a suitable work surface.
3. Perform the resistance measurements on the modulator and power amplifier
MOSFETs as described in “Resistance measurements” on page 1-57 .
4. Perform the diode checks on the protection and free-wheel diodes as described in
“Protection Diode checks” on page 1-57 and “Free-Wheel Diode checks” on page 1-58 .