Juniper MX104 Hardware Guide

b. The cable with very low resistance (indicating a closed circuit) to chassis ground
is the return cable (+).
For +24V:
a. The cable with very low resistance (indicating a closed circuit) to chassis ground
is the DC input cable (–).
b. The cable with very high resistance (indicating an open circuit) to chassis ground
is the return cable (+).
8. Secure each power cable lug to the terminal with the flat washers and screw (see
Figure 57 on page 176). Apply up to 27.4 lb-in. (3.1 Nm) of torque to each screw. Do not
overtighten the screw. (Use a number 2 Phillips screwdriver.)
a. Secure the positive DC source power cable lug to the return (+) terminal.
b. Secure the negative DC source power cable lug to the input (–) terminal.
CAUTION: Ensurethat each power cablelugseatsflushagainstthe surface
of the terminal block as you are tightening the screws. Ensure that each
screw is properly threaded into the terminal. Applying installation torque
to the screw when improperly threaded may result in damage to the
terminal.
CAUTION: The maximum torque rating of the terminal screws on the DC
power supply is 27.4 lb-in. (3.1 Nm). The terminal screws may be damaged
if excessive torque is applied. Use only a torque-controlled driver to tighten
screws on the DC power supply terminals. Use an appropriately sized
driver, with a maximum torque capacity of 27.4 lb-in. or less. Ensure that
the driver is undamaged and properly calibrated and that you have been
trained in its use. You may wish to use a driver that is designed to prevent
overtorque when the preset torque level is achieved.
9. Replace the clear plastic cover over the terminals on the faceplate.
10. Connect each DC power cable to the appropriate external DC power source.
NOTE: For information about connecting to external DC power sources,
see the instructions for your site.
11. Switch on the external circuit breakers to provide voltage to the DC power source
cable leads. Observe the system LED on the front of the router. If the DC power cable
is correctly installed and functioning normally, the system LED lights green steadily.
175Copyright © 2017, Juniper Networks, Inc.
Chapter 23: Replacing Power System Components

Juniper MX104 Specifications

General

Product Name	MX104
Product Series	MX Series
Switching Capacity	80 Gbps
Throughput	80 Gbps
Operating System	Junos OS
Humidity	5% to 90% non-condensing
Interfaces	10 Gigabit Ethernet, Gigabit Ethernet
Power Supply	Dual redundant AC or DC
Cooling	Front-to-back airflow
Memory	8 GB
Operating Temperature	0°C to 40°C