Troubleshooting the Installation 5-7
Troubleshooting Overview
•The MBus module on the RP monitors the progress of the CSC power-up sequence.
When the CSC is powered up, the MBus module on the RP turns on its DC-DC
converter to power its own electronics.
•The master MBus module on the RP then sends instructions to each line card and each
SFC to power up; the MBus module on each card then turns on its own onboard DC-DC
converter.
—The MBus module on each line card monitors its progress during the power-up
sequence. During this process, the line card processor performs its own boot
sequence to load line card operating software. When the line card boot process is
complete, the card communicates its status to the master MBus module on the RP.
—The MBus module on each SFC also monitors its own progress during the power-
up sequence. When the SFC boot process is complete, the cards likewise
communicate their status to the master MBus module on the RP.
•As the power on and boot process progresses for the RP and each installed line card, the
status of each card is given in the alphanumeric displays near the bottom of its faceplate.
The top display is powered by the DC-DC converter on the card; the bottom display is
powered by the +5 VDC provided through the backplane by the AC-input or DC- input
power supply(ies).
By checking the status LEDs on the power supply(ies) and the alphanumeric displays on
the RP and each line card, you can generally determine when and where the system failed
during the startup sequence.
The following section describes what you should expect to see in the power supply LEDs
on system startup.

Power Supply Status LEDs

When you start up the system by turning on the rotary power switch on the power supply
faceplate, the following should occur:
•The green INPUT OK LED on each DC-input power supply or the green AC INPUT
OK LED on each AC-input power supply should go on immediately and stay on as long
as source power is applied to the system.