NEC SV8500 Operation And Maintenance Manual - page 666
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CHAPTER 5
Operation Procedure for System with PIR
4.4.2
Check Point (2/2)
When repairing a unit fault, consider the following items:
(1) Speech paths and control paths in the unit are connected to line/trunks via the MUX circuit cards. Be sure
to check the alarm lamps on the MUX circuit cards, and check to see if the front cable between each MUX
circuit card and TSW circuit card is connected correctly. Figure 5-11 and Figure 5-12 show the block dia-
gram within the unit.
(2) The MUX circuit cards are operating in the ACT/STBY modes under control of the CPU circuit. When the
ACT-side CPU has detected a fault in the ACT-side MUX circuit card, CPU changeover is executed and
the ACT/STBY mode of the Speech Path System is also changed over. When both of the MUX circuit cards
have become faulty, all the lines/trunks in that unit are placed into make-busy state. (If a PFT circuit card
is located in that specific unit, the PFT is activated.) Figure 5-13 shows the location of the MUX cards.
(3) When both units in a specific PIR are faulty, it is possible that the PWR circuit card mounted in that specific
PIR is faulty. In such a case, refer to
Section 4.9, Power Supply Fault
.
Figure 5-11 Unit Control Block Diagram (Dual Configuration)
MUX 0
Clock
(B)
(A)
Speech
Path
TSW
MUX 1
LC/TRK
LC/TRK
PM
Line/
Trunk
Circuit Card
Control of
TP
Clock
(B)
Speech
Path
(A)
TSW
SYMBOLS
: Circuit Card
: Control on ACT/STBY of Speech Path Systems
: Control on ACT/STBY of Clock Systems
(A)
(B)