Nautel NX15, Troubleshooting Manual

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NX25/NX15 Troubleshooting Manual Responding to alarms
Issue 5.0 2016-05-06 Page 1-41
Responding to alarms
Controller: External PDM Inhibit
The external PDM inhibit is wired to the control/interface PWB.
A
Controller: External PDM Inhibit
alarm indicates that an external PDM inhibit command is
present. The alarm could be caused by an short circuit in the external wiring path to the control/
interface PWB or a fault in the switching circuitry on the control/interface PWB. Troubleshoot as
follows:
1. If the control/interface PWB’s shorting jumper E2 is in the
INT
position (shorting pins 2
and 3), verify the dc voltage between J6-4 and ground on the control/interface PWB is
approximately 15 V. This signifies there is no external PDM inhibit command.
2. If the control/interface PWB’s shorting jumper E2 is in the
EXT
position (shorting pins 1
and 2), verify the dc voltage between J6-3 and J6-4 on the control/interface PWB is 0 V. This
signifies there is no external PDM inhibit command.
3. If the conditions in Step 1 and Step 2 are met, suspect the control/interface PWB and if
necessary, replace it (see “Control/interface PWB replacement” on page 1-60 ).
Controller: Interlock Open
A
Controller: Interlock Open
alarm indicates an external interlock is open. The transmitter’s RF
output will be inhibited.
The external interlock input is wired to the control/interface PWB by the end user and triggered by
the conditions that they set (e.g., the state of the door to the transmitter room).
1. Gain access to the control/exciter panel (A11) (see Figure 1.6 on page 1-54 ) by opening the
control cabinet’s front door. The door is not latched and just swings open to the left.
2. Connect a digital multimeter (set to measure dc) between J6-2 of the control/interface PWB
and ground.
3. If 15 V is present on J6-2, the external interlock circuit is intact and the probable cause of the
alarm is a defective monitoring circuit. Suspect the control/interface PWB and if necessary,
replace it (see
“Control/interface PWB replacement” on page 1-60 ).
4. If 15 V is not present on J6-2, measure the voltage between J6-5 (external 15 V) of the
control/interface PWB and ground, then between J6-1 (+15 V) and ground.