Alcatel-Lucent 7750 SR-a4, Installation Manual, Page: 178 / 232

Removing and Replacing a PSU
178 7750 SR-a4 and SR-a8 Installation Guide
Removing a –48 VDC PSU
Figure 60 and Figure 61 show how to remove a –48 VDC PSU from the 7750 SR-a chassis.
Table 90 describes the features.
Figure 60: Removing a –48 VDC PSU (7750 SR-a4)
Danger:
• Ensure that all power from the DC circuit is OFF. Locate the circuit breaker on the panel
board that serves the DC circuit. Switch the circuit breaker to the OFF position. For extra
safety, lock out the circuit breaker by taping the handle of the circuit breaker in the OFF
position.
• When wiring the unit, the ground connection must always be made first and
disconnected last.
• The correct wiring sequence is ground/negative to ground/negative and positive/return
to positive/return.
Note:
Refer to 7750 SR-a –48 VDC PSU LED and Connectors on page 139 for a
description of the PSU.
7750
S R-a4 Fan Tray
Pwr
S tat
S lot Layout
1/1 XP
1/2
1/3
1/4
1
CPM A
CPM B
7750 SR-a4
S ervice Router
Pwr
Stat
Pwr
7
7
5
0
MD
A
-a
X
P
1
-1
0
0
G
B-C
F
P
Stat
Lnk
Pwr
7
7
5
0
M
DA
-a
20
-1
G
B-
TX
Stat
Lnk
1
Act
2
Lnk
3 Act
4
Lnk
5
Act
6 Lnk
7
Act
8 Lnk
9 Act
10
Lnk
11
Act
12
Lnk
13
Act
14 Lnk
15 Act
16
Lnk
17
Act
18 Lnk
19
Act
20
Sy
n
cE/1
58
8
Alarms
1PPS
ACO/LT
Critical
Lnk DTE
Pwr
7
7
5
0
CP
M
-a
Stat
Console M
gmt
O
ES
B
ITS
Compact Flash
DCE Act Lnk
Act
Major
Minor
Sy
n
cE/
15
88
Alarms
1PPS
ACO/LT
Critical
Lnk DTE
Pwr
7
7
5
0
C
P
M
-a
Stat
Console M
gmt
O
E
S
B
ITS
Compact Flash
DCE Act Lnk
Act
Major
Minor
Pwr
7750
SR
-a
Stat
Pwr
Stat
77
50
M
D
A
-a
XP
10
-1
0G
B-
S
FP
+
10
Lnk
Act
9
Lnk
Act
8
Lnk Act
7
Lnk Act
6
Lnk Act
5
Lnk Act
4
Lnk Act
3
Lnk Act
2
Lnk Act
1
Lnk Act
Pwr
7
7
5
0
M
DA
-a
44
-1
G
B-
CS
FP
/S
FP
Stat
Lnk/Act
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
25 26 27 28
29 30 31 32
33 34 35 36
37 38 39 40
41 42 43 44
17 18 19 20
21 22 23 24
A
ir
F
ilt
er
Ac
c
es
s
77
5
0
S
R
-a4
2
4
3
1
245 8 2