ATT System 25 Maintenance Manual

							AT&T555-520-105
Issue 2, October 1987
AT&T SYSTEM 25
MAINTENANCE MANUAL 
						

							©1987 AT&T
All Rights Reserved
Printed in USA
TO ORDER COPIES OF THIS DOCUMENT REFER TO DOCUMENT
NUMBER 555-520-105.
Contact: Your AT&T sales representative or
Call: 800-432-6600, Monday to Friday between 7:30 am
and 6:00 EST, or
Write: AT&T Customer Information Center
2855 North Franklin Road
P.O. Box 19901
Indianapolis, Indiana 46219
Every effort was made to ensure that the information in this document
was complete and accurate at the time of printing. However, information
is subject to change. This document will be reissued periodically to
incorporate changes.
Maintenance Manual
Prepared by System 25
Document Development Group and the
AT&T Documentation
Management Organization 
						

							DANGER
Do not open the fan assembly or remove rear cabinet cover before
unplugging the cabinet from the electrical outlet. Wait at least five
minutes after unplugging the power cord before removing the rear
cover or power supply. The AT&T System 25 cabinets are not user
serviceable. Some voltages inside the cabinets are hazardous.
This equipment is to be serviced only by qualified technicians.
CUSTOMER WARNING
The Installation and Test Manual and the Maintenance Manual are
designed for use by qualified service technicians only. Technician
qualification includes completion of an AT&T hands-on instructor-led
course covering installation and maintenance for this product. The
use of these documents by anyone else might void the warranty.
Hazardous electrical voltages are present inside this product. 
						

							FCC NOTIFICATION AND REPAIR INFORMATION
AT&T SYSTEM 25
This telephone equipment is registered with the Federal Communications
Commission (FCC) in accordance with Part 68 of its Rules. In compliance
with the Rules, be advised of the following:
MEANS OF CONNECTION
Connection of this telephone equipment to the nationwide
telecommunications network shall be through a standard network interface
USOC RJ21X jack. Connection to private line network channels requires
USOC RJ2GX jack for tie lines or USOC RJ21X jack for off-premises station
lines. These can be ordered from your telephone company.
NOTIFICATION TO THE TELEPHONE COMPANY
If the system is to be connected to off-premises stations (OPSs), you must
notify the telephone company of the OPS class of service, OL13C, and the
service order code, 9.0F.
Upon the request of the telephone company, inform them of the following:
—
The Public Switched Network lines and the Private lines to which
you will connect the telephone equipment.
—
The telephone equipments registration number and ringer
equivalence number (REN) from the label on the equipment.
—
For private line connections, provide the facility interface code, TL31M
for tie lines. You must also specify the service order code, 9.0F. 
						

							—
—The quantities and USOC numbers of the jacks required.
For each jack, provide the sequence in which lines are to be connected;
the type lines and the facility interface code and the ringer equivalence
number by position, when applicable.
This telephone equipment should not be used on coin telephone lines.
Connection to party line service is subject to state tariffs.
REPAIR INSTRUCTIONS
If you experience trouble with this telephone equipment, contact the AT&T
Business Customer Service Center on 1-800-242-2121. The telephone
company may ask that you disconnect this equipment from the network until
the problem has been corrected or until you are sure that this equipment is
not malfunctioning.
RIGHTS OF THE TELEPHONE COMPANY
If your telephone equipment causes harm to the telephone network, the
telephone company may discontinue your service temporarily. If possible,
they will notify you in advance. But if advance notice isnt practical, you will
be notified as soon as possible. You will be informed of your right to file a
complaint with the FCC.
Your telephone company may make changes in its facilities, equipment,
operations, or procedures that could affect the proper functioning of your
equipment. If they do, you will be notified in advance to give you an
opportunity to maintain uninterrupted telephone service. The voice terminals
described in this manual are compatible with inductively coupled hearing aids
as prescribed by the FCC.
HEARING AID COMPATIBILITY
The voice terminals described in this manual are compatible with inductively
coupled hearing aids as prescribed by the FCC. 
						

							FCC REGISTRATION INFORMATION
Registration NumberAS593M-71565-MF-E
Ringer Equivalence
0.5A
Network InterfaceRJ21X or RJ2GX
PRIVATE LINE SERVICE
Service Order Code9.0F
Facility Interface Code
lTie LinesTL31M
lOff-Premises StationsOL13C
FCC WARNING STATEMENT
Federal Communications Commission (FCC) Rules require that you be
notified of the following:
l
l
lThis equipment generates, uses, and can radiate radio frequency energy
and, if not installed and used in accordance with the instruction manual,
may cause interference to radio communications.
It  has  been  tested  and  found  to  comply  with  the  limits  for  a  Class  A
computing device pursuant to Subpart J of Part 15 of FCC Rules, which
are designed to provide reasonable protection against such interference
when operated in a commercial environment.
Operation of this equipment in a residential area is likely to cause
interference in which case the user at his or her own expense will be
required to take whatever measures may be required to correct the
interference. 
						

							AT&T System 25 Maintenance
INTRODUCTION1-1
Organization1-2
Equipment Needed1-3
Assumption1-3
Precautions1-4
GENERAL MAINTENANCE INFORMATION
System Errors and Alarms
Error Log
Emergency Transfer
Alarm and Status Indicators
Switches and Test Points
System Administration Terminal
Maintenance Tests
2-1
2-2
2-2
2-3
2-3
2-4
2-4
2-5
SYSTEM HARDWARE
Overview
Digital Switch
Station Interconnect Panel
Trunk Access Equipment
Terminal Equipment
Wiring
Emergency Transfer Unit
3-1
3-1
3-3
3-3
3-5
3-7
3-7
3-7
-i- 
						

							Digital Tape Unit3-8
Common Control and Switching Network3-8
Common Control3-10
Switching Network3-16
SYSTEM SOFTWARE
General
Switched Services Software
Administrative Software
Maintenance Software
Memory Allocation
Real-Time Constraints
Software Partitioning
Memory Circuit Pack
Call Processor Circuit Pack
TDM Bus
Port Circuit Packs
Step-By-Step Call Description
4-1
4-1
4-1
4-1
4-2
4-2
4-3
4-3
4-4
4-4
4-5
4-5
4-7
MAINTENANCE STRATEGY
General Procedures
Total System Failures
Port Problems
Common Control Problems
Station, Wiring, and Trunk Problems
Automatic Maintenance Tests
Maintenance Failure
5-1
5-3
5-3
5-3
5-4
5-4
5-5
5-5
ERROR LOG6-1
Accessing the Error Log From the SAT6-3
Error Log Dictionary6-5
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							OPERATING THE DIGITAL TAPE UNIT7-1
Setting up the DTU7-1
Saving Translations7-2
Verifying Translations7-3
Restoring Translations7-4
CLEARING SYSTEM-DETECTED TROUBLES
General Trouble-Clearing Techniques
Consulting Error Log
Reseating and Replacing Circuit Packs
Removing and Restoring Power
Restarting the System
Interpreting Circuit Pack LEDs
Clearing Specific System Troubles
Complete System Failure
Common Control Trouble
Circuit Pack Trouble
Frontplane Ribbon Connector Trouble
Power Supply Trouble
Fan Assembly Trouble
Overheating Trouble
Backplane and Cabinet Trouble
Emergency Transfer Unit Trouble
8-1
8-1
8-1
8-1
8-3
8-4
8-8
8-9
8-9
8-9
8-11
8-12
8-12
8-17
8-18
8-18
8-26
CLEARING USER-REPORTED TROUBLES9-1
Administration Equipment Troubles9-1
Time-Keeping Troubles9-2
Voice Terminal and Wiring Troubles9-2
Voice Transmission Troubles9-3
7300H Series Terminal Troubles9-4
-iii- 
						

							Trunk Troubles
Outgoing Trunk Problems
Incoming Trunk Problems
Error Log Interpretation: Loop Start Trunks
Error Log Interpretation: Ground Start
Trunks
DID Trunks Troubles
Special Port Circuit Options for Stations
and Trunks
Data Line Troubles
Multiple or Undiagnosable Troubles
9-5
9-5
9-6
9-6
9-7
9-8
9-9
9-11
9-13
REFERENCE DOCUMENTATION10-1
ABBREVIATIONS AND ACRONYMS11-1
GLOSSARY12-1
INDEX13-1
-iv-