Nautel XR12, Troubleshooting Manual, Page: 33 / 283

XR12 Troubleshooting Manual Responding to alarms
Issue 3.0 2009-07-28 Page 1-13
Fan P/S fault
The 48 V power supply used for the fans is monitored and will report a fault if the voltage is outside
the range of 48 V ± 10%.
1. Check for accompanying alarms in the
Status
screen. If there is a
LVPS Fault
, troubleshoot it
first (see LVPS fault ).
2. Measure the voltage between R48-LHS and ground on the distribution PWB. If it is outside
the range of 48 V ± 10%, press
RF Off
, switch off ac power and wait five minutes. Adjust the
V OUT
potentiometer (R10) - on the fan power supply PWB - a half turn clockwise (if the
measured voltage was too low) or counterclockwise (if the measured voltage was too high).
3. Switch on ac power, press
RF On
and repeat Step 2 until the measurement is 48 V. If the
voltage cannot be adjusted, suspect the fan power supply PWB.
4. Otherwise recalibrate the 48 V supply to read the measured voltage (see “Calibrating meters”
on page 2-21 of the Operating and Maintenance Manual ).
5. Verify there is less than 1 V on U34 pin 12 (surface-mount part) on the control/display
PWB. If not suspect the control/display PWB.
RF drive P/S fault
The 62 V dc power supply used for the RF drive is monitored and will report a fault if the voltage is
outside the range of 62 V ± 10%.
The alarm could result from a fault in the RF drive power supply PWB, or faulty detection circuitry
on the RF drive power supply PWB. Troubleshoot an
RF Drive P/S Fault
alarm as follows.
1. Check for accompanying alarms in the
Status
screen. If there is a
LVPS Fault
or
Fan P/S
Fault
, troubleshoot it first (see LVPS fault or Fan P/S fault ).
2. Measure the voltage between R50-RHS and ground on the distribution PWB. If it is outside
the range of 62 V ± 10%, adjust the RF drive power supply PWB’s
VOLTAGE CONTROL
potentiometer R3 to restore the voltage within its acceptable range.
WARNING:
Potentially lethal voltages exist on the lower, front panel of the
transmitter. Use caution when troubleshooting power supply alarms.