Installing a T640 SCG

To install a replacement SCG (see Figure 1):

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
2. Carefully align the sides of the SCG with the guides in the SCG slot.
3. Grasp the SCG by its handle, and slide it straight into the chassis until it contacts the midplane.
4. Tighten the captive screws on the corners of the SCG faceplate.
5. To bring the SCG online, press the online/offline button until the green OK LED lights.
6. To verify that the SCG is installed correctly and is functioning normally, check the LEDs on the SCG faceplate. The green OK LED should light steadily. If the SCG is master, the blue MASTER LED should also light steadily.

   To check the status of the SCGs, use the following CLI command:

   user@host> show chassis environment scg

   For more information about using the CLI, see the Junos OS manuals.

7. If an external clocking device was connected to one or both RJ-48 ports, reconnect the cables.

Figure 1: Installing an SCG