Replacing a DC Power Supply on the SRX3600 Services Gateway
To remove a DC power supply:
- Switch off the dedicated facility circuit breaker for the power supply being removed. Follow your site's procedures for ESD.
- Make sure that the voltage across the DC power source cable leads is 0 V and that there is no chance that the cables might become active during the removal process.
- Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to one of the ESD points on the chassis. For more information about ESD, see Preventing Electrostatic Discharge Damage to the SRX3600 Services Gateway.
- Remove the clear plastic cover protecting the terminal studs on the faceplate.
- Remove the screws and washers from the terminals. Use a number-2 Phillips screwdriver to loosen and remove the screws.
- Remove the cable lugs from the terminals.
- Carefully move the power cables out of the way.
- Push the tab on the right edge of the power supply to the left.
- Pull the power supply straight out of the chassis.
Figure 1: Removing a DC Power Supply

- Orient the replacement power supply so that the tab is on the
right side, as shown in Figure 2.
Figure 2: Inserting a DC Power Supply

- Using both hands, slide the replacement power supply straight
into the chassis until the power supply is fully seated in the chassis
slot. Make sure the tab on the right edge of the power supply clicks
into place. The power supply faceplate should be flush with any adjacent
power supply faceplate.

Note: Be sure to have the power supply oriented correctly. The tab must be on the right and click into place when fully seated. If the power supply does not insert easily or does not become flush with the chassis, you may have the power supply upside down.
- Remove the clear plastic cover protecting the terminal studs on the faceplate.
- Remove the screws and washers from the terminals.
- Secure each power cable lug to the terminal studs,
first with the washer, then with the screw. Apply between 23 lb-in.
(2.6 Nm) and 25 lb-in. (2.8 Nm) of torque to each screw.
- Secure each positive (+) DC source power cable lug to a RTN (return) terminal.
- Secure each negative (–) DC source power cable lug to a -48V (input) terminal.

Caution: You must ensure that power connections maintain the proper polarity. The power source cables might be labeled (+) and (–) to indicate their polarity. There is no standard color coding for DC power cables. The color coding used by the external DC power source at your site determines the color coding for the leads on the power cables that attach to the terminal studs on each power supply.

Note: The DC power supplies in slots PEM0 and PEM1 must be powered by dedicated power feeds derived from feed A, and the DC power supplies in slots PEM2 and PEM3 must be powered by dedicated power feeds derived from feed B. This configuration provides the commonly deployed A/B feed redundancy for the system.

Note: For information about connecting to DC power sources, see SRX3600 Services Gateway DC Power System Electrical Specifications.
- Replace the clear plastic cover over the terminal studs on the faceplate.
- Verify that the power cabling is correct, that
the cables are not touching or blocking access to services gateway
components, and that they do not drape where people could trip on
them. If the power supply is correctly installed and functioning normally,
the LED on the power supply lights green steadily.

Note: You must have an SFB and a Routing Engine installed in the services gateway for the power supply to turn on automatically.

