NEC Neax 2400 Imx System Operations And Maintenance Manual

CHAPTER 5 NDA-24238
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FAULT REPAIR PROCEDURES
Check the faulty line on the MDF.
Isolate the faulty line to the in-house wiring
side and to the system side.
Connect the test telephone to the system side
and check to see if dial tone can be heard.
When Dial Tone (DT) is heard Check the in-house wirings.
Replace the station telephone set with a spare.
When no DT or side tone is
heardCheck LT cables.
Replace the LC circuit card with a spare.
When DT is not heard, but side
tone can be...

NDA-24238 CHAPTER 5
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FAULT REPAIR PROCEDURES
1.4 Line Fault - When Dialing Results in Wrong Connection
Note:If a circuit card is replaced because only one line is
faulty, no other lines in that circuit card can be used
until the replacement is complete.
When a call addressed to a specific station
has terminated to another stationCheck to see if Call Forwarding-All Calls data
has been deleted.
Check the faulty line on the MDF. On the MDF, isolate the faulty line to the in-
house...

CHAPTER 5 NDA-24238
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FAULT REPAIR PROCEDURES
1.5 Line Fault - When Bell Does Not Ring
Note:If a circuit card is replaced because only one line is
faulty, no other lines in that circuit card can be used
until the replacement is complete.
Call the faulty station line by Station-to-
Station calling and check to see if the bell
of the telephone rings.Replace the telephone set and check to see if
its bell rings.
Check the faulty line on the MDF. Isolate  the  faulty  line  to  the...

NDA-24238 CHAPTER 5
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FAULT REPAIR PROCEDURES
1.6 When Call Cannot Be Answered and Speech Cannot Be Made
Note:If a circuit card is replaced because only one line is
faulty, no other lines in that circuit card can be used
until the replacement is complete.
Check the faulty line on the MDF. Isolate  the  faulty  line  to  the  in-house  wiring
side and to the system side.
Connect the test telephone to the system side.
Call the faulty line by station-to-station
calling.
When speech can...

CHAPTER 5 NDA-24238
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FAULT REPAIR PROCEDURES
1.7 Dterm Fault
Note 1:If a circuit card is replaced because only one line
is faulty, no other lines in that circuit card can be
used until the replacement is complete.
Note 2:If any of the in-house cable wirings short-circuit,
the POW ALM lamp on the ELC circuit card
lights. Remove the cause of the short-circuit and
initialize the ELC circuit card.
When OPE lamp on the ELC circuit card
does not illuminateConfirm that MB switch of the ELC...

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FAULT REPAIR PROCEDURES
Check the faulty line on the MDF. Isolate  the  faulty  line  to  the  in-house  wiring
side and to the system side.
Connect the test D
term to the system side.
Confirm speech by Station-to-Station calling.
When no speech can be made. Check LT cables.
Replace ELC circuit card with a spare.
When speech can be made. Check to see if the modular plug is firmly
connected with the D
term.
Check the wiring inside the rosette.
Check the in-house...

CHAPTER 5 NDA-24238
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FAULT REPAIR PROCEDURES
2. TRUNK FAULT
This paragraph explains the fault repair procedure when a fault, shown in Table 5-3, has occurred to a specific
trunk.
2.1 Check Point
When repairing a trunk fault, consider the following items:
(1) Check alarm lamps on trunk circuit cards.
(2) When an outgoing call cannot be originated to a specific trunk or when an incoming call cannot be termi-
nated from a specific trunk, check Tenant Restriction Data (assigned via ATNR...

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FAULT REPAIR PROCEDURES
Table 5-4  Timings for Trunks
ITEMS FOR STATUS 
SUPERVISIONCONDITIONS FOR SUPERVISION TIMING SPECIFICATIONS
1 Detection of Call 
Termination Ring Down System
Detection by ringing signal (20Hz) from 
the opposite office.
 Loop System
Detection by loop from the opposite office.
E&M System
Detection by incoming signal (ground or –
48V) on E (RG2) lead.Ringing signal of more than 4 cycles 
is detected within 800 ms.
Detection within 16 ms...

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FAULT REPAIR PROCEDURES
Table 5-5  Timings for Senders
ITEMS FOR STATUS 
SUPERVISIONCONDITIONS FOR SUPERVISION TIMING SPECIFICATIONS
1 Sender Acknowledge Wait 
Ti merTiming limit for waiting to receive connection 
acknowledgement signal from the opposite 
office after seizing the opposite office.4 sec. (standard) 
Timing can be assigned using ASYD 
SYS 1 Index 130 command.
2 Sender Prepause Timer Time from sender seizure till sending of the 
1st digit where...

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FAULT REPAIR PROCEDURES
2.2 Trunk Control
Trunk circuit cards are controlled from the CPU via the MUX. Each trunk line in a specific trunk circuit
card is controlled by the Port Microprocessor (PM) in a trunk circuit card. Figure 5-2 shows the control
route of the trunk circuit card.
Figure 5-2   Controlling Trunk Circuit Cards and Speech Path
TRK
TDSW/INT
GT
CPU
CPR TSW
MDF
LT Cable
LT Cable Control Signal
Speech Path
Control SignalCOT/TLT
Symbols:
           :...