Nautel NX50, Troubleshooting Manual

Page: 104 / 205

NX50 Troubleshooting Manual Responding to alarms
Page 1-94 Issue 6.0 2019-04-01
1. Set the transmitter to its RF Off state and turn off (disable) the ac power at the source.
Lift the air filter (slide it up) to verify the LEDs on the power module interface PWBs
are off (green when on), indicating the B+ capacitors are discharged. Open the rear
door of the cabinet and verify the six ac indicator LEDs on the rectifier assembly are
off (amber when on). For additional safety, measure the dc voltage across the + and -
terminals of any of the large, electrolytic capacitors on the floor of the cabinet as well
as the line-to-line and line-to-ground voltages at the ac input terminals. There should be
little or no ac or dc voltage. DO NOT PROCEED if either the ac or dc voltage is
greater than 5 V.
2. Remove the E1 end of the yellow wire that connects the RF Voltage Probe (A41) to
the filter. (see Figure 1.28 on page 1-93 and Mechanical Drawing MD-19).
3. Disconnect BNC connector P24 from J1 of the RF Voltage Probe.
4. Remove and retain the two M5 screws that secure the voltage probe to the side of the
transmitter’s chassis.
5. Obtain a replacement RF Voltage Probe (Nautel Part # 207-6111-01).
6. Complete the replacement procedure by reversing Step 2 and Step 4 .
7. Close the rear door and turn on (enable) the ac power source to resume transmitter
operation.