Chapter
11
Maintain and Replace Cooling System Components
his chapter describes how to maintain and replace cooling system components:
Tools and Parts Required on page 153
Maintain and Replace the Air Filter on page 154
Maintain and Replace the Fan Tray on page 155
Maintain the Impeller Assemblies on page 157
Replace the Lower Impeller Assembly on page 158
Replace the Upper Impeller Assembly on page 159
Tools and Parts Required
You need the following tools and parts to replace cooling system components:
Phillips (+) screwdrivers, numbers 1 and 2
ESD grounding wrist strap
Electrostatic bag or antistatic mat for each component removed
Maintain and Replace Cooling System Components
153
Maintain and R eplace the Air Filter
Maintain and Replace the Air Filter
Check the air filter regularly for dust and debris, replacing it as necessary. The air filter is
hot-removable and hot-insertable, as described in “Field-Replaceable Units (FRUs)” on
page 4. Take note of the following caution, however.
Do not operate the router for more than a few minutes
when the air filter has been removed. The fans and
impellers are powerful enough to draw in foreign material,
such as bits of wire, through the unfiltered air intake,
which could damage router components.
See the following sections:
Remove the Air Filter on page 154
Install the Air Filter on page 155
Remove the Air Filter
The air filter is located below the craft interface at the front of the chassis (see Figure 1). The
air filter weighs less than 0.5 lb (0.2 kg), and you must remove it in order to remove the
lower impeller assembly.
To remove the air filter, use the following procedure (see Figure 67):
1.
Attach an ESD wrist strap to your bare wrist, and connect the wrist strap to one of the
two ESD points on the chassis.
2.
Grasp the sides of the air filter and firmly pull it out from the chassis.
Figure 67: Remove the Air Filter
1039
Craft interface display
154
M40 Internet Router Hardware Guide
Maintain and Replace the Fan Tray
Install the Air Filter
To install the air filter, follow this procedure (see Figure 68):
1.
Attach an ESD wrist strap to your bare wrist, and connect the wrist strap to one of the
two ESD points on the chassis.
2.
Grasp the sides of the air filter and push it firmly over the air intake, inserting its metal
prongs into the chassis.
1064
Figure 68: Install the Air Filter
Maintain and Replace the Fan Tray
The fan tray is located at the rear of the chassis, beneath the upper impeller assembly (see
Figure 2). To check the status of the fans in the fan tray, issue the show chassis environment
command. The output refers to the individual fans in the fan tray as the Rear Left Fan,
Rear Center Fan, and Rear Right Fan:
user@host> show chassis environment
Class Item
. . .
Fans Top Impeller
Bottom Impeller
Rear Left Fan
Rear Center Fan
Rear Right Fan
. . .
Status
Measurement
OK
OK
OK
OK
OK
Spinning
Spinning
Spinning
Spinning
Spinning
at
at
at
at
at
normal
normal
normal
normal
normal
speed
speed
speed
speed
speed
For further description of the output from the command, see the JUNOS Internet Softw are
Oper ational Mode Command R eference: Pr otocols, Class of Service , Chassis, and
Management .
To replace the fan tray, perform the following procedures:
Remove the Fan Tray on page 156
Install the Fan Tray on page 156
Maintain and Replace Cooling System Components
155
Maintain and R eplace the F an Tray
Remove the Fan Tray
The fan tray is located at the rear of the chassis, beneath the upper impeller assembly (see
Figure 2). On some M40 routers, the tray is covered by a protective screen. You do not need
to remove the screen before removing the fan tray from the chassis. The fan tray weighs
approximately 5 lb (2 kg).
To remove the fan tray, follow this procedure (see Figure 69):
1.
Attach an ESD strap to your bare wrist and connect the strap to one of the ESD points on
the chassis.
2.
Unscrew the screws at the outer corners of the fan tray (not the screws that attach the
protective screen), using a Phillips screwdriver if necessary.
3.
Grasp the sides of the fan tray and pull firmly to slide it out of the chassis.
1040
Figure 69: Remove the Fan Tray
Install the Fan Tray
To install the fan tray, follow this procedure (see Figure 70):
156
1.
Attach an ESD strap to your bare wrist and connect the strap to one of the ESD points on
the chassis.
2.
Slide the fan tray into the chassis.
3.
Align the screws at the corners of the fan tray with the mounting holes at the edges of
the opening and use a Phillips screwdriver to tighten the screws.
M40 Internet Router Hardware Guide
Maintain the Impeller Assemblies
1053
Figure 70: Install the Fan Tray
Maintain the Impeller Assemblies
The router has two non-interchangeable impeller assemblies. The lower impeller is located
behind the craft interface at the front the chassis (see Figure 1), and the upper assembly is
located above the fan tray at the rear of the chassis (see Figure 2). They work together to cool
the Packet Forwarding Engine components.
During normal operation, the impellers run at less than full speed. The following conditions
automatically cause the impellers to run at full speed and trigger the indicated alarm:
One of the impellers fails (red alarm).
One of the impellers is removed (yellow alarm). For removal instructions, see the
following sections:
Remove the Lower Impeller Assembly on page 158
Remove the Upper Impeller Assembly on page 159
The router temperature exceeds the “temperature warm” threshold (yellow alarm).
The temperature of the router exceeds the maximum (“temperature hot”) threshold (red
alarm and automatic shutdown of the power supplies).
For more information about impeller-related alarms, see “Hardware and Interface Alarm
Messages” on page 192.
To check the status of the impeller assemblies, issue the show chassis environment
command. The output refers to the Top and Bottom impellers, as shown in this example:
user@host> show chassis environment
Class Item
...
Fans Top Impeller
Bottom impeller
...
Status
Measurement
OK
OK
Spinning at normal speed
Spinning at normal speed
For further description of the output from the command, see the JUNOS Internet Softw are
Oper ational Mode Command R eference: Pr otocols, Class of Service , Chassis, and
Management .
Maintain and Replace Cooling System Components
157
Replace the L ower Impeller Assembly
Replace the Lower Impeller Assembly
The lower impeller assembly is located behind the craft interface at the front the chassis (see
Figure 1) and works together with the upper assembly to cool the Packet Forwarding Engine
components. It is hot-removable and hot-insertable.
To replace the fan tray, perform the following procedures:
Remove the Lower Impeller Assembly on page 158
Install the Lower Impeller Assembly on page 159
Remove the Lower Impeller Assembly
The lower impeller assembly is located behind the craft interface at the front the chassis (see
Figure 1). It weighs approximately 9 lb (4 kg).
To remove the lower impeller assembly, follow this procedure (see Figure 71):
1.
Remove the air filter, if it is installed on the chassis. For instructions, see “Remove the
Air Filter” on page 154.
2.
Attach an ESD strap to your bare wrist and connect the strap to one of the ESD points on
the chassis.
3.
Unscrew the three screws at the bottom edge of the assembly, using a Phillips
screwdriver if necessary.
4.
Grasp the sides of the assembly, and slide it about halfway out of the chassis.
5.
Move one of your hands underneath the assembly to support it, and slide it completely
out of the chassis.
Figure 71: Remove the Lower Impeller Assembly
Impellers
Craft interface display
1023
Screws
158
M40 Internet Router Hardware Guide
Replace the Upper Impeller Assembly
Install the Lower Impeller Assembly
The lower impeller assembly is located behind the craft interface at the front the chassis (see
Figure 1). To install it, follow this procedure (see Figure 72):
1.
Attach an ESD strap to your bare wrist and connect the strap to one of the ESD points on
the chassis.
2.
Grasp the sides of the assembly, and align the rear with the slide guides in the chassis.
3.
Slide the assembly all the way into the chassis until it contacts the backplane.
4.
Using a Phillips screwdriver, tighten the three captive screws at the bottom edge of the
assembly to seat it firmly in the chassis.
5.
Install the air filter as described in “Install the Air Filter” on page 155.
Figure 72: Install the Lower Impeller Assembly
1062
Screws
Replace the Upper Impeller Assembly
The upper impeller assembly is located at the top rear of the chassis, above the fan tray (see
Figure 2), and works together with the lower assembly to cool the Packet Forwarding Engine
components. It is hot-removable and hot-insertable.
To replace the upper impeller assembly, perform the following procedures:
Remove the Upper Impeller Assembly on page 159
Install the Upper Impeller Assembly on page 160
Remove the Upper Impeller Assembly
The upper impeller assembly is located at the top rear of the chassis, above the fan tray (see
Figure 2). It weighs approximately 10 lb (4 kg).
1.
Attach an ESD strap to your bare wrist and connect the strap to one of the ESD points on
the chassis.
2.
Unscrew the captive screws at the bottom corners of the assembly, using a Phillips
screwdriver if necessary.
Maintain and Replace Cooling System Components
159
Replace the Upper Impeller Assembly
3.
Grasp the handle at the top of the assembly, and slide it about halfway out of the chassis.
4.
Move one of your hands underneath the assembly to support it, and slide it completely
out of the chassis.
1021
Figure 73: Remove the Upper Impeller Assembly
Install the Upper Impeller Assembly
To install the upper impeller assembly, follow this procedure (see Figure 74):
1.
Attach an ESD strap to your bare wrist and connect the strap to one of the ESD points on
the chassis.
2.
Grasp the handle at the top of the assembly and slide the assembly all the way into the
chassis.
3.
Using a Phillips screwdriver, tighten the thumbscrews at the lower corners of the
assembly.
1054
Figure 74: Install the Upper Impeller Assembly
160
M40 Internet Router Hardware Guide
">
