DEFINITY Enterprise Communications Server Release 7
Maintenance for R7r
555-230-126 Issue 4
June 1999
Maintenance Object Repair Procedures
9-1383SNC-BD (Switch Node Clock Circuit Pack)
9
Figure 9-83. SNC Functions
SNC LEDs
SNC circuit packs have the stand ard red, green and yell ow LEDs. The red and
green LEDs operate as usual: red means an alarm c ondition and green ind icates
maintenance testing in prog ress. If the yellow LED is lit this indicates that the
SNC is the active circuit pac k, supplying timing to the carrier. In a high reliability
system (duplicated SPE, simplex PNC), the standby SNC on a carrier will be
unlit. In a critical reliability system (d uplicated PNC), an SNC on a standby switc h
node carrier will be lit since it is providing timing for the standby carrier.
Clear Firmware-Counters Command
SNC firmware generates error reports indep endently of technician-d emanded
tests. Therefore, the test board UUCSS clear command will not affect the error
status reported by firm ware. The clear firmware-counters command will c lear
all firmware-generated errors unc onditionally.
The clear firmware-c ounters UUCSS command sends a downlink mess age to
the SNC circuit pack, causing it to clear out its firmware error counters and failure
Clock Duplication
9 Clock Busses
SNC-BD
SNC-BD
SNC-LINK
(aux data 1)
SNC-REF
SNC-LINK
(aux data 2)
TPN Links
Reference Signals
Serial Channel
.
Loop
Locked
Phase
Circuit
Generation
Clock
Microcontroller
.
...
Active SNC
Standby SNC
SNI 1e02
SNI 1e20
SNI 1e03
.
Microcontroller
TPN
Oscillator
Stratum 3
Control
16
SNI (TN573)
17