Alcatel-Lucent 9500 MXC User Manual page 744

ODU -48V Supply
Probable Cause
Recommended Actions
Additional Information
Vol. VI-B-18
to the node. Confirm by measuring the -48 Vdc supply with a voltmeter.
If the alarm is not supported by other indications and measurement, the
voltage sensing circuit is faulty. Replace the RAC.
ODU -48 volt supply out of tolerance. This is a warning alarm.
Main 48 Vdc power supply is outside limits of -40.5 to -60 Vdc, or the voltage
drop on the ODU cable is excessive due to poor connections or a combination of
poor connections and a low -48Vdc power supply.
1. Check for other alarms to determine how critical the alarm is. In particular,
check the NCC/IDU -48V alarm, and for a Node check the RAC -48V Supply
alarm. Depending on the malfunction, the node may otherwise operate
satisfactorily.
2. Check the -48V ODU Supply voltage in the CT Performance screen, and use
a voltmeter to measure the -48V supply at the front panel power connector.
• If the -48V supply is normal, (and for the Node there is no RAC -48V
Supply alarm), suspect excessive voltage drop on the ODU cable, or the
voltage sensor circuit in the ODU.
3. If a cable related problem is suspected check the ODU cable, connectors, and
connector weatherproofing. Disconnnect the cable at the ODU and apply a
short-circuit between inner and outer conductors. Measure the resistance at
the node end. For 9913 coax, resistance should be not more than 0.01 ohms
per meter (0.003 ohms per ft). Bear in mind that for a 100m run, a resistance
of about 1 ohm is expected so care must be taken to ensure correct
measurement.
4. If there are no other alarms, the node is operating normally, and the ODU
cable is OK, then the voltage sensor circuit and/or its processing in the ODU
is the likely cause. Replace the ODU.
CAUTION: use extreme care if attempting to measure voltage at the RAC/IDU
front panel ODU connector, or at the ODU end of the cable. Inadvertently
shorting the inner to outer will blow the surface-mounted PCB fuse on the RAC,
which is not a field replaceble item. Repair will not be covered by warranty.
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