User's Manual Part 2

SCCP Backplane Troubleshooting – continued
PRELIMINARY
1X SCt4812ET Lite BTS Optimization/ATP
08/01/2001
6-24
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 SCCP Shelf Power Supply Modules
Table 6-24: No DC Input Voltage to Power Supply Module
Step Action
1 Verify DC power is applied to the frame. Determine if any
circuit breakers are tripped.
* IMPORTANT
If a breaker has tripped, remove all modules from the SCCP
shelf and attempt to reset it.
– If breaker trips again, there is probably a cable or breaker
problem within the frame or DC PDA.
– If breaker does not trip, there is probably a defective
module or sub–assembly within the shelf. Perform the
tests in Table 2-3 to attempt to isolate the module.
2 Verify that the PS1 and PS2 circuit breakers on the DC PDA
are functional.
3 Remove the frame rear access panel (Figure 2-1), and use a
voltmeter to determine if the input voltage is being routed to
the SCCP backplane. Measure the DC voltage level between:
S The PWR_IN_A and PWR_RTN_A contacts on the
extreme right side at the rear of the backplane
S The PWR_IN_B and PWR_RTN_B contacts on the
extreme right side at the rear of the backplane
– If the voltage is not present, there is probably a cable or
circuit breaker problem within the frame or DC PDA.
4 If everything appears to be correct, visually inspect the PS1
and PS2 power supply module connectors.
5 Replace the power supply modules with a known good
module.
6 If steps 1 through 4 fail to indicate a problem, an SCCP
backplane failure has occurred (possibly an open trace).
6