ATT System 25 Installation And Maintenance Manual

MAINTENANCE
Figure 4-10.TDM Signal Designations on Cabinet Backplane
4-75 

MAINTENANCE
Figure 4-11.Power Designations onCabinet Backplane
4-76 

_ MAINTENANCE
Each of the 12 universal carrier slots has 48 pins on the backplane for
connection to station and trunk ports. The 48 pins are divided into eight
groups of 6 pins each, one group for each port circuit. Lead
designations consist of the lead name suffixed by the group number (for
example, TA.2, RA.2). Specific functions depend on the type of port CP.
Table 4-D provides the 25-pin connector to backplane pin designations.
Typical backplane problems include power supply failure, sudden failure...

MAINTENANCE
Table 4-D.
25-Pair Connector to Backplane Designations
25-Pin-Conn.
Call
Proc
Pin No.
Wire
ColorGS
Trunk
ZTN76LS
Trunk
ZTN77Tip Ring
Line
ZTN78ATL
Line
ZTN79MET
Line
TN735Backplane
Pin No.
(Slots 1-12)
26
1
27
2
28
3
29
4
30
5
31
6
32
7
33
8
34
9
35
10
36
11
37
12
38
13
39
14
40
15
41
16
42
17
43
18
44
19
45
20
46
21
47
22
48
23
49
24
50
25W-BL
BL-W
W-O
O-W
W-G
G-W
W-BR
BR-W
W-S
S-W
R-BL
BL-R
R-O
O-R
R-G
G-R
R-BR
BR-R
R-S
S-R
BK-BL
BL-BK
BK-O
O-BK
BK-G
G-BK
BK-BR
BR-BK
BK-S
S-BK
Y-BL
BL-Y...

MAINTENANCE
Table 4-D.25-Pair Connector to Backplane Designations Contd)
25-Pin-Conn..
Pin No.Wire
ColorDID
Trunk
TN753Tie
Trunk
TN760BAux.
Trunk
TN763Data
Line
TN726Analog
Line
TN742Analog
Line
TN746BDS1
Interface
TN767Backplane
Pin No.
(Slots 1-12)
26
1
27
2
28
3
29
4
30
5
31
6
32
7
33
8
34
9
35
10
36
11
37
12
38
13
39
14
40
15
41
16
42
17
43
18
44
19
45
20
46
21
47
22
48
23
49
24
50
25W-BL
BL-W
W-O
O-W
W-G
G-W
W-BR
BR-W
W-S
S-W
R-BL
BL-R
R-O
O-R
R-G
G-R
R-BR
BR-R
R-S
S-R
BK-BL
BL-BK
BK-O
O-BK
BK-G...

MAINTENANCE
8 CABLE LENGTH
CONNECTOR 1
CONNECTOR 0
CONNECTOR 2
STOCKLIST
DESCRIPTION
25-PR PLUG
8-FT, 8-PR, 24-GC, CABLE
25-PR RECEPTACLE
SPACER (NOTE 1)
NOTES:
1.
2.
3.
INSTALL SPACER AT CONNECTOR CABLE CLAMP TO ENSURE PROPER
CABLE RETENTION.
ITEMS 1 AND 3 SHALL BE EQUIPPED WITH SCREWS TO FACILITATE
ASSEMBLY TO B25A CABLES.
LABEL CONNECTORS AS SHOWN: 0,1,2.
CONN 0CONN 2
2626
11
2729
24
2832
37
2935
4
10
3438
9
13
3541
1016
3644
1119
3747
1222WIRING LIST
CONN 0
CONN 1
38
26
131
39
29
144
40
32
157
4135...

MAINTENANCE
Emergency Transfer Unit Trouble
If the Emergency Transfer Unit (ETU) will not enter the power failure mode, do
the following steps:
1.
2.
3.
Unplug the cable bringing the control signal from port 7 or 8 on the
CPU/Memory CP to the ETU. This cable terminates in a modular jack
that is inserted in a modular plug labeled CPU on the left-hand side of
the ETU.
If the ETU goes into the power failure mode, the CPU/Memory CP is
probably faulty or a wiring problem exists. Plug the cable back in, then...

MAINTENANCE
CLEARING USER-DETECTED TROUBLES
User-reported troubles are usually associated with voice or data terminal
equipment or trunks.They can result from system-detected errors and are
often solved by clearing system error conditions or alarms.
This section presents trouble-clearing techniques and procedures for user-
reported troubles.
Maintenance routines for data terminals and Asynchronous Data Units (ADUs)
are not contained in this section (although some basic routines for clearing...

MAINTENANCE
Note:For problems with administration equipment that is not
connected on a dedicated basis, refer to the Terminal
Operations Manual, 555-540-710.
Time-Keeping Troubles
Symptoms:
Clock
Procedures:
1.Resetdoesn’t reflect current time or date.
clock from SAT (see the Administration Manual). Clock has
tolerance of plus or minus 3 minutes per month. Variances outside
this range indicate a faulty clock and require replacement of the
CPU/Memory CP. Time must be reset
Voice Terminal and Wiring...

6.
7.
8.
9.
Voice
Check CP translations from the SAT to be sure that this CP has
Check LEDs on CP. The red LED will be lighted if a fault on the CP
affects all ports. Also, the red LED may be lighted if one or a few
ports are faulty.
Check Error Log for relevant messages.
Reseat the CP even if the red LED is dark. (See “Reseating and
Replacing Circuit Packs” under “Routine Maintenance” in this
section.) Replace the faulty CP.
Transmission Troubles
Symptoms:
Voice terminals not receiving tones....