NEC SV8500 Operation And Maintenance Manual - page 680
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CHAPTER 5
Operation Procedure for System with PIR
4.5.3
Speech Path System Fault - When Dial Tone (DT) Cannot Be Heard
Faulty Situation:
•
Dial Tone (DT) cannot be heard.
•
[1-A] Both TSW Failure (Permanent)
•
[1-E] Both TSW Clock Failure
•
[4-C] Both TSW Ready Failure
•
[23-Y] MUX Clock Failure
Note:
For dual system configuration, if a system message indicates that both systems are faulty, first repair the
fault in the indicated system and then proceed to repair the PIR in the other system.
(1) Check to see if the TSW circuit card is making poor contact.
(a) Place the TSW circuit card in STBY mode referring to How to Control Switching Block.
(b) Set MB switch of the TSW circuit card UP.
(c) Extract the TSW 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 TSW MBR switch, PLO MBR switch (1-IMG only), and MB switch of the TSW circuit card UP
and insert the circuit card into its mounting slot.
(e) Set MB switch of the TSW circuit card DOWN.
(f)
Set TSW MBR switch DOWN.
(g) Check if a station-to-station connection can be normally set up.
(2) Check PCM cables.
(a) Check the Front cables.
(b) Initialize the system by pressing the INIT button on the EMA card and see if a station-to-station con-
nection can be set up.