NV5/NV3.5 Troubleshooting Manual Responding to alarms
Page 1-42 Issue 3.2 2014-12-10
+12 V Power Supply Replacement
See Figure 1.6 on page 1-41 and Figures MD-2 and MD-7 in the Mechanical Drawings section
(Section 6) of this manual.
1. Open the front door and remove the blank panel to the right of the RF power modules.
Retain hardware and locate the suspect +12 V power supply module [U1 (A) or U2 (B)].
2. Temporarily disconnect ac power from the suspect +12 V power supply module by
disconnecting the appropriate ac plug from the ac distribution assembly (A6). Disconnect P2
from A6J2 for +12 V power supply module A (U1). Disconnect P5 from A6J6 for +12 V
power supply module B (U2). The +12 V power supply module’s green lamp should turn off.
Verify ac power has been disconnected from the +12 V power supply module by using a
digital voltmeter to verify 0 V between the L and ground terminals and between the N and
ground terminals.
3. Disconnect all wiring from the +12 V power supply module’s terminal block, noting the
specific destination of each wire.
4. Using a 4 mm hex key (not provided), loosen the two M5 cap screws securing the +12 V
power supply module to the transmitter. Remove the +12 V power supply module and its
mounting plate from the transmitter.
5. Remove the two M4 screws that secure the +12 V power supply module to its mounting
plate.
6. Locate or obtain a replacement +12 V power supply module (Nautel Part # UG57). Reverse
Step 1 and Step 5 to reinstall the new +12 V power supply module. If necessary, refer to
Section 4, “Wiring/connector lists” on page 4-1 to locate wiring details.
7. From the AUI’s System Review page, select Controller and view the +12V A or +12 V B
meter, depending on which +12 V module was replaced. If necessary, adjust the
potentiometer on the rear of the +12 V module until the meter reading is 12.6 V.
8. The transmitter should resume normal operation and the alarm should clear.
WARNING:
Lethal voltages exist inside the transmitter when the power is turned
on. Follow replacement instructions carefully to ensure safety for
maintenance personnel during power supply replacement.
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