• Before beginning any procedures requiring access to the chassis interior, locate the emergency power-off switch for the room in which you are working.
• Disconnect all power and external cables before moving a chassis.
• Do not work alone in potentially hazardous conditions.
• Never assume that power has been disconnected from a circuit; always check.
• Do not perform any action that creates a potential hazard to people or makes the equipment unsafe.
• Carefully examine your work area for possible hazards such as moist floors, ungrounded power extension cables, and missing safety grounds.

Electrostatic discharge (ESD) damage occurs when electronic cards or components are improperly handled, and can result in complete or intermittent failures. All line cards consist of a printed circuit card that is fixed in a metal carrier. Electromagnetic interference (EMI) shielding and connectors are integral components of the carrier. Although the metal carrier helps to protect the cards from ESD, use an antistatic strap each time you handle the modules. Handle the carriers by the edges only; never touch the cards or connector pins.

Caution

Always tighten the captive installation screws on all system components when you are installing them. These screws prevent accidental removal of the module, provide proper grounding for the system, and help to ensure that the line card connectors are properly seated in the backplane. Captive screws should be torqued to 6-8 in-lbs to ensure proper grounding and mechanical support. Never use cordless or corded drills to tighten screws; power screwdrivers and hand tools are acceptable.

Static electricity can harm delicate components inside your system. To prevent static damage, discharge static electricity from your body before you touch any of your system components. As you continue to work on your system, periodically touch an unpainted metal surface on the computer chassis.

The following guidelines can prevent ESD damage:

• Always use an ESD-preventive wrist or ankle strap and ensure that it makes good skin contact. Before removing a card from the chassis, connect the equipment end of the strap to the ESD plug at the bottom of the chassis below the power entry modules. Ensure that the chassis or rack or both have a grounding cable installed.
• Handle line cards by the faceplate and carrier edges only; avoid touching the card components or any connector pins.
• When removing a card, place the removed module component-side-up on an antistatic surface or in a static-shielding bag. If the module will be returned to the factory, immediately place it in a static-shielding bag.
• Avoid contact between the modules and clothing. The wrist-strap protects the card from ESD voltages on the body only; ESD voltages on clothing can still cause damage.
• When transporting a sensitive component, first place it an antistatic container or packaging.
• Handle all sensitive components in a static-safe area. If possible, use antistatic floor pads and workbench pads.

Caution

For safety, periodically check the resistance value of the antistatic strap. The measurement should be between 1 and 10 megohms.

This section provides information about environmental, power, cabling, and mounting requirements. Ensure that you have met all of these requirements before you install your product.

You need the following tools to install and cable the Cisco CMC:

• Torque wrench capable of 5 to 12 ft-lbs (6.8 to 16.3 Nm)

• 4-inch to 6-inch extension for torque wrench

• 1/8-inch slot screwdriver for the F-connectors

• 1/2-inch socket for the strand clamp bolts

• #2 Phillips-head screwdriver for the grounding screw

• Heavy-duty wire cutters or snips for cutting the cable

• Deburring tool for filing the rough edges

You need the following tools to install and cable the Cisco uBR-MC3GX60V-RPHY line card:

• T-10 Torx driver tool

• 1/4-inch flathead screwdriver

• Blank Cisco uBR10012 slot cover (if required)

• ESD-preventive wrist strap

• Antistatic surface, such as a mat or antistatic bag

The table below provides the torque specifications for the fasteners used with the Cisco CMC.

Fastener	Torque Specification	Illustration
Strand clamp mounting bracket bolts	5 ft-lb to 8 ft-lb (6.8 Nm to 10.8 Nm)
Housing closure bolts	5 ft-lb to 12 ft-lb (6.8 Nm to 16.3 Nm)
5/8" port plugs	6.7 ft-lb (9 Nm)
PG11-to-5/8" adapter	4.63 ft-lb (6.25 Nm)
RJ-45 port PG16 plug	5.55 ft-lb (7.5 Nm)
Power port PG11 gland	Plastic: 3 ft-lb (4 Nm) Metal: 4.63 ft-lb (6.25 Nm)
RJ-45 port PG16 gland	Plastic: 4.44 ft-lb (6 Nm) Metal: 5.5 ft-lb (7.5 Nm)
PG11 F-connector	4.63 ft-lb (6.25 Nm)
5/8" F-connector	6.7 ft-lb (9 Nm)

Installation or maintenance of the Cisco CMC requires opening the housing to access the internal components.

This section provides information on how to remove and install the following accessories located inside the Cisco CMC.

Accessory	Description	Illustration
Attenuator pads	An attenuator pad produces flat (even) loss across the forward and reverse frequency spectrums. It is used during the station balancing to adjust signal levels. The loss (in dB) produced by an attenuator pad is equal to the value printed on the top of the attenuator pad. An attenuator pad with 75 Ω printed on the top works as a 75 ohm terminator. Important: Do not change the attenuator pads, unless specified by the system design.
Equalizers	An equalizer produces linear tilt. It must be used on the Cisco CMC if the output tilt does not have the desired output tilt. The EQ value specified on the equalizer is the amount of tilt from lowest to highest frequency (52 to 1002 MHz).
Signal director—Splitter	A splitter splits the RF input signal to feed two RF output ports. It is used for configuring the 4-way RF configuration on the Cisco CMC.
Signal director—Jumper	A jumper routes the RF input signal to the RF output port. It is used for configuring the 2-way RF configuration on the Cisco CMC.
AC shunts	An AC shunt is used for configuring the power direction in the Cisco CMC with the 60VAC power supply unit. Use the red AC shunt for the RF input port and black AC shunts for the RF output ports. Warning    Remove all the AC shunts if they are installed in the Cisco CMC before connecting the coaxial cables to the F-connectors. Note    Do not use AC shunts in the Cisco CMC with the 220VAC power supply unit.

These accessories can be removed and installed in the Cisco CMC through the cutouts in the base cover.

Figure 5. Location of the Accessories Inside the Cisco CMC

The Cisco CMC supports two types of fiber adapters:

• SC/APC-LC/APC fiber adapter

• SC/APC-SC/APC fiber adapter

The Cisco CMC contains two pre-installed SC/APC-SC/APC fiber adapters. Perform this procedure to install additional fiber adapters.

The Cisco CMC supports Gigabit Ethernet SFP and Ethernet Passive Optical Network (EPON) SFP.

Use the PG16 gland to connect the RJ-45 cable to the Cisco CMC.

Figure 12. PG16 Gland

The Cisco CMC supports two types of PG16 glands for the RJ-45 port:

• PG16 gland with one hole for single Ethernet connection

• PG16 gland with two holes for dual Ethernet connection

Forward-Path I/O Configurations

Forward-path refers to the signals received at the Cisco CMC from the headend. These signals are amplified in the Cisco CMC and routed to the subscribers through the cable modems. The Cisco CMC supports the following forward-path RF configurations:

• 4-way forward output RF configuration (default RF configuration)

• 2-way forward output RF configuration

Reverse-Path I/O Configurations

Reverse-path refers to the signals received at the Cisco CMC from the cable modem. These signals are amplified in Cisco CMC and returned to the headend optically through the fiber portion of the network. The reverse-path RF configuration is not used in all networks. The Cisco CMC supports the following reverse-path RF configurations:

• 4-way reverse input RF configuration (default RF configuration)

• 2-way reverse input RF configuration

The following sections provide information on how to enable the different RF configurations on the Cisco CMC:

Proper housing closure is important to maintain the Cisco CMC in good working condition. Proper closure ensures a good seal against the environment and protects the internal modules.

Caution

Avoid moisture damage and RF leakage. Follow the procedure exactly as shown below to ensure a proper seal.

The Cisco CMC has waterproof rubber and EMI gasket to seal the equipment.

Figure 25. Location of the Waterproof Rubber and EMI Gasket on the Cisco CMC

The following types of cables are used with Cisco uBR-MC3GX60V-RPHY line cards to connect to a switch or an OLT:

• RJ-45 10/100/1000BASE-T copper cable

• Single-mode or multimode fiber-optic cable