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Self-Diagnostics
Field Checks
Troubleshooting Procedures
Turn On the Power Supply Module to initialize the XBN. At the
beginning of the XBN's initialization, the ERROR LED and all point
LEDs turn On for approximately three seconds.
1. First, the On condition of the LEDs tests whether or not all the LEDs
are functioning.
2. Then the Static RAM (SRAM) self-diagnosis is implemented. If the
SRAM test fails, an alternating odd/even pattern on the LEDs blinks in
1/2 second intervals. Power must be cycled and the XBN reinitialized.
If the SRAM test continues to fail, replace the module.
3. All self-diagnostics are conducted within the three seconds, and if
successful, the LEDs turn Off (except the POWER LED).
a. If the ERROR LED stays lit, the XBN is defective and must be
returned to the factory.
b. If the POWER LED turns Off (and the Power Supply Module
LEDs remain On), a power failure is occurring either in the
connections between the Power Supply Module and XBN, or
inside the XBN. If possible, test the connections by installing a
known functioning XBN module into the slot.
-
If the functioning XBN verifies the connections, replace the
faulty XBN module.
-
If a functioning XBN fails in the slot, a problem may reside in
the power supply or NCU/NEU base frame. Refer to the
technical bulletins for those units.
Perform the following steps to field check the XBN. Steps 4 and 5 must
be checked with the presence of functioning N2 communications, as
checked in Step 3.
1. Ensure that the POWER LED lights and remains lit to indicate that the
supply voltage is good.
2. Verify that the ERROR LED never lights (with the exception at power
On). If this LED constantly flashes, or remains illuminated, or if all
the LEDs constantly flash, a severe hardware failure is indicated.
Cycle power; if the error continues, replace the module.
3. Next, verify that the device is being polled. This is evident if the
XMIT (transmit) LED lights, which indicates that the XBN is replying
to a poll.
Point Multiplex Modules—Multiplex Binary
33
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