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 heard.Replace the LC circuit card with a spare.
ATTENTIONContents
Static Sensitive
Handling
Precautions Required
A
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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 wiring side and to the system side.
Connect the test telephone to the system side.
Repeat station-to-station connections and
check to see if the connection is established
normally.
When  the  dialed  station  is  called The station telephone set is faulty. Replace the
station telephone set with a spare.
When a wrong connection 
occursReplace the LC circuit card with a spare.
AT T E N T I O NContents
Static Sensitive
Handling
Precautions Required
START
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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  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 and check to see if the bell rings.
When the bell does not ring Replace the LC circuit card with a spare.
When the bell rings The in-house wiring side is faulty. Confirm
that the A wire is not short-circuiting with
ground.
ATTENTIONContents
Static Sensitive
Handling
Precautions Required
START
END 
						

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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 be made Replace the telephone set with a spare.
When speech cannot be made Replace the LC circuit card with a spare.
ATTENTIONContents
Static Sensitive
Handling
Precautions Required
START
END 
						

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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 circuit
card is in ON position (UP).
Confirm that station data (ASDT command)
in the ELC circuit card is assigned.
Replace ELC circuit card with a spare.
When BL lamp for each line is flashing or
illuminating on the ELC circuit cardConfirm that MB switch of the ELC circuit
card is in ON position (UP).
Use MBST command to confirm that ELC
circuit card has not been placed into make-
busy state.
Check the station data (ASDT command)
assignment.
Replace the ELC circuit card with a spare.ATTENTIONContents
Static Sensitive
Handling
Precautions Required
START
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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 wiring for any
abnormality.
Replace the D
term with a spare.
ATTENTIONContents
Static Sensitive
Handling
Precautions Required
A
END 
						

							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 command) and Route Re-
striction Data (assigned via ARSC command).
(3) Three-Way Conference Trunk (CFT) is on the MUX (PH-PC36) circuit cards. If a three-way conference
call cannot be established, check the MUX cards.
(4) If the present timing for supervising the trunk/sender status is considered to be responsible for the fault,
change the timing. The specifications for timings that can be changed with respect to trunks and senders
are shown in Table 5-4 and Ta b l e  5 - 5.
Table 5-3  Trunk Fault Situation
TRUNK FAULTY SITUATION REFERENCE SECTION
ORT No connection can be set up.
PB/DP signals are erroneously received or cannot be received.Section 2.3, Trunk (ORT, SND, 
CFT) Fault
SND No connections can be set up.
PB/DP signals are erroneously sent out or cannot be sent out.
CFT No connections can be set up.
No three-way calling can be made.
Noise gets in an established connection.
COT
TLT
DTINo connections can be set up.
A connection results in no speech.
Noise gets in an established connection.Section 2.4, Trunk (COT, TLT, DTI) 
Fault 
						

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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 after call 
termination.
2 Acknowledge Signal 
Sending Wink Signal
 Delay Start160 ms (standard)
Timing can be assigned using ARTD 
command.
3 Detection of Release at the 
time of Incoming 
ConnectionE&M System
 Loop System288 ms (standard)
160 ms (standard)
Timing can be assigned using ARTD 
command.
4 Timing for Restricting Call 
Origination after ReleaseAfter release of the user’s trunk or the trunk at 
the opposite office has been detected, a new 
call origination is restricted.3070 ms (standard) 
Timing can be assigned using ARTD 
command.
5 Seizure of Opposite Office  Loop System
Closure of DC loop.
E&M System
Supply of outgoing call signal (ground or –
48V) onto M (DL) lead.
6 Detection of Acknowledge 
Signal Wink Signal
 Delay StartTiming is assigned using ARTD 
command.
7 Trunk  Hold  Time Even if answer signal has not reached from the 
opposite office, the call is regarded as 
answered. If DP Signal is 10 sec. (standard) 
after dial pulses are sent out
Timing can be assigned using 
ARTD command.
 If PB Signal is 30 sec. (standard) 
after seizure of the trunk
Timing can be assigned using 
ASYD SYS 1 Index 156 (only 
when 2nd Dial Tone System).
8 Detection of Release at the 
time of Outgoing 
Connection Loop System
Detection of polarity reversal across tip and 
ring.
E&M System
Detection of Release Signal (ground or –
48V) on E lead.608 ms (standard)
Timing can be assigned using ARTD 
command. 
						

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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 connection acknowledgment is 
made by interface with the opposite office.DP: 3 sec. (standard) 
PB: 2.5 sec. (standard) 
Timing can be assigned using ASYD 
SYS 1 Index 131 command.
3 Sender Inter-digit Timer Inter-digit timing for the numbers to be sent 
out by the sender.For DP
10 pps: 860 ms (standard)
20 pps: 460 ms (standard)
Timing can be assigned using 
ASYD SYS 1 Index. 132 com-
mand.
For PB
60 ms/120 ms (to be selected by
ONSG of ARTD command.)
Timing can be changed using 
ASYD SYS 1 Index 133 com-
mand. 
						

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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:
           :  Circuit Card                              :  Speech Path
          :  Control Signal
TSW:  PH-SW12                     GT:  PH-GT09
MUX:  PH-PC36                     ISAGT:  PZ-GT13
TRK
PM
MUX
TRKControl Signal
Speech PathORT/SND
TRK
PM
CFT
Note
TRKControl Signal
Speech PathORT/SND
TRK
PM MUX
Control Signal
Speech Path
CFT
Note
Note:
Eight CFTs are provided on the MUX (PH-PC36) cards.
Network
ISAGT
TRKLT Cable
LT Cable COT/TLT
TRK
PM