This document describes the steps for removal of AC/DC PSM in MX2020.

MX2020’s power subsystem consists of two zone each powered with 9 PSM (power supply modules). Each PSM module has 2 input feeds, with one active at a time.

In customer setup, bottom portion PSM0 to PSM8 have both Inputs connected. The top portion PSM9 to PSM17 have Input 0 unplugged.

Since PSM9 to PSM17 are disconnected from input, Below alarms are continuously logged for these PSMs:

Jul 19 03:39:39 re0-ROUTER1 chassisd[27747]: CHASSISD_PEM_INPUT_BAD: Input 1 failure for power supply 11 (status bits: 0x0); check circuit breaker

Jul 19 03:39:39 re0-ROUTER1 chassisd[27747]: CHASSISD_PEM_INPUT_BAD: Input 0 failure for power supply 15 (status bits: 0x4); check circuit breaker

Customer have planned to offline PSM which are not in use.

Before you remove a PSM, be aware of the following:

Note: After powering off a PSM, wait at least 60 seconds before turning it back on.

Note: The minimum number of AC PSMs changes based on the configuration.

Please refer document for power management in MX2020 :

https://www.juniper.net/documentation/us/en/hardware/mx2020/topics/task/maintain-mx2020-power-usage.html

Removing an MX2000 AC Power Supply Module

NOTE: The AC PSM is hot-swappable when a minimum number of PSMs installed and operational.

1. With one PSM installed and operational, remove any additional PSMs by turning the power switch to the off (O) position.
2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
3. Loosen the two captive screws on the PSM faceplate.
4. While grasping the handle on the PSM faceplate with one hand, use your other hand to guide the PSM away from the chassis.
5. Pull the PSM straight out of the chassis. CAUTION:Do not touch the power connectors on back of the PSM. They can get damaged.
6. Place the PSM module into an antistatic bag.
7. NOTE: Each PSM slot not occupied by a AC PSM must be covered by a PSM blank panel.

CAUTION: To maintain proper cooling and prevent thermal shutdown of the operating PSM, each PSM slot must contain either a PSM or a blank panel. If you remove a PSM, you must install a replacement PSM or a blank panel shortly after the removal.

WARNING: The AC PSMs have no circuit breakers that can physically disconnect AC current from the router. After AC feeds have been connected to the PDM, the AC voltage is always present on the power midplane and is distributed to the PSM connectors on the power midplane.

Figure 1: Removing an MX2020 Router AC Power Supply Module

Removing an MX2000 Router DC Power Supply Module 

NOTE: After powering off a PSM, wait at least 60 seconds before turning it back on.

To remove a DC PSM Figure2.

NOTE: The minimum number of DC PSMs change, based on the configuration.

1. With one PSM installed and operational, remove any additional PSM by turning the power switch to the off (O) position.
2. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
3. Loosen the two captive screws on the PSM faceplate. Apply between 10 lb-in. (1.13 Nm) to 12 lb-in. (1.35 Nm) of torque to each screw. Do not overtighten the screws.
4. While grasping the handle on the PSM faceplate with one hand, use your other hand to guide the PSM away from the chassis.
5. Pull the PSM straight out of the chassis.
6. WARNING: To avoid damage, do not touch the power connectors in back of the PSM.
7. Place the PSM module into an antistatic bag.
8. NOTE: Each PSM slot not occupied by a DC PSM must be covered by a PSM blank panel.

Figure 2 : Removing an MX2020 Router DC Power Supply Module