Unit Fault - When Dial Tone (Dt) Cannot Be Heard - NEC Univerge SV8500 Operation And Maintenance Manual

4.4.4

Unit Fault - When Dial Tone (DT) Cannot Be Heard

Faulty Situation:
• Dial Tone (DT) cannot be heard except within a unit.
• [4-T] Both MUX Failure / [4-S] MUX Ready Failure
• [23-Y] MUX Clock Failure
For dual system configuration, if a system message indicates that both systems are faulty, first repair the
Note:
fault in the indicated system and then proceed to repair the PIR in the other system.
<<For Dual Configuration>>
(1) Check to see if the MUX circuit card is making poor contact.
(a) Set the MUX circuit card into STBY mode. Flip the MBR switch of ACT side TSW circuit card from
ON OFF.
(b) Set the MB switch of the MUX circuit card UP.
(c) Extract the MUX circuit card from its mounting slot and clean the contact portion. If cleaning cannot
be done, repeat insertion and extraction of the circuit card two or three times.
(d) Set the MB switch of the MUX circuit card UP and insert the circuit card into its mounting slot.
(e) Set the MB switch of the MUX circuit card DOWN.
(f) Check to see if a station-to-station connection can be set up within the faulty unit.
(2) Check by replacing the MUX circuit card with a spare.
(a) Place the MUX circuit card into STBY mode. Flip the MBR switch on the ACT side TSW circuit card
from ON OFF.
(b) Replace the MUX circuit card. Refer to
Circuit Card.
(c) Change the new MUX circuit card to ACT mode.
(d) Check to see if a DT (Dial Tone) connection can be set up within the faulty unit.
CHAPTER 5 Operation Procedure for System with PIR
Section 1.5, Replacement Procedure of MUX (Multiplexer)
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