Nautel NX50, Troubleshooting Manual

Page: 106 / 205

NX50 Troubleshooting Manual Responding to alarms
Page 1-96 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. Refer to Figure 1.29 on page 1-95 for the location of the RF Current Probe (A42).
3. Remove the left hand side panel, viewed from the front of the transmitter, by
removing and retaining the three M5 screws on the top of the transmitter that secures
the panel. Lift upwards to remove the panel.
4. Remove and retain the eight M5 screws for the RF Current Probe access panel, located
on the side of the transmitter.
5. Disconnect the BNC connector P23 from J1 of the RF Current Probe. Refer to
Mechanical Drawing MD-20.
6. See Figure 1.30 on page 1-97 . Using a 19-mm socket, remove and retain the M12 bolt
and hardware. When re-installing the bolt, torque to 24 ft-lbs.
7. Using a 13-mm socket, remove and retain the three M8 bolts and hardware. When re-
installing the bolts, tighten appropriately (no torque setting recommended).
8. Obtain a replacement RF Current Probe (Nautel Part # 207-6213-10).
9. Complete the replacement procedure by reversing Step 3 and Step 7 .
10. Turn on (enable) the ac power source to resume transmitter operation.