User Manual

SCCP Backplane Troubleshooting – continued
PRELIMINARY
SC 4812ETL BTS Optimization/ATP
08/15/2000
6-18
DC Power Problems
Potentially lethal voltage and current levels are routed to
the BTS equipment. This test must be carried out with a
second person present, acting in a safety role. Remove all
rings, jewelry, and wrist watches prior to beginning this
test.
WARNING
No DC Input Voltage to Power Supply Module
Table 6-22: No DC Input Voltage to Power Supply Module
Step Action
1 Verify DC power is applied to the BTS frame. Verify there are
no breakers tripped.
* IMPORTANT
If a breaker has tripped, remove all modules from the
applicable shelf supplied by the breaker and attempt to reset it.
– If breaker trips again, there is probably a cable or breaker
problem within the frame.
– If breaker does not trip, there is probably a defective
module or sub–assembly within the shelf.
2 Verify that the SCCP shelf breaker on the BTS frame breaker
panel is functional.
3 Use a voltmeter to determine if the input voltage is being
routed to the SCCP backplane by measuring the DC voltage
level on the PWR_IN cable.
– If the voltage is not present, there is probably a cable or
breaker problem within the frame.
– If the voltage is present at the connector, reconnect and
measure the level at the “VCC” power feed clip on the
distribution backplane. If the voltage is correct at the
power clip, inspect the clip for damage.
4 If everything appears to be correct, visually inspect the power
supply module connectors.
5 Replace the power supply module with a known good
module.
6 If steps 1 through 4 fail to indicate a problem, the SCCP
backplane failure (possibly an open trace) has occurred.
6