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Corrective MaintenancePower Subsystem
C H A P T E R
( D R A F T L A B E L ) A L P H A D R A F T - C I S C O C O N F I D E N T I A L
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This chapter describes fault isolation techniques for the VCO/4K power subsystem. Refer to the Cisco
VCO/4K Mechanical Assemblies for a description of the power subsystem components.
Power Subsystem Operation
Starting Up the System
To start the VCO/4K:
Step 1
Turn on the power switch to the right of the power connector on the power entry module. (The VCO/4K
is on when the switch is in an upward position.) See Figure 5-1 or Figure 5-2.
Step 2
Check the power LED on the power supply module. Check both LEDs on both power supply modules in
a redundant system. The LED is green under normal operating conditions.
Figure 5-1
Power Entry Module with Input Power Type Specied
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Power Subsystem Operation
Figure 5-2
Power Entry Module Without Input Power Type Specied
Power LED
When the power is off, the left indicator LED on the power supply module is not illuminated (see
Figure 5-3). When the power switch is on and the power LED is not illuminated, either a fuse (see the
Spare Fuse Kit section on page 5-4) or the power supply module needs to be replaced. Green indicates
that the power is on and operation is normal. Red is a warning that there are voltages in the power supply
module that are over or under the required voltages or that there is a problem with load sharing. The
power supply module needs to be replaced. See the Removal and Replacement Procedures section on
page 5-4.
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Alarms
Figure 5-3
Power Supply Module
Turning Off the System
To turn off a VCO/4K system, move the power switch on the power entry module to the off (down)
position. The LED is no longer illuminated.
Alarms
Two events occur simultaneously whenever voltage monitoring on the control board of the power supply
module detects either an overvoltage or an undervoltage condition: An alarm is sent to the Alarm Arbiter Card (AAC) and is visually displayed on the AAC. The red
MAJOR LED turns on, and the yellow AUX1 LED turns on. The power LED on the power supply module turns red.
When these two events occur, you must remove and replace the power supply module. See the Removal
and Replacement Procedures section on page 5-4.
50162
Ring generator LED
Hand grip
Power LED
Ring generator
Control
board
Location of
interlock
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Spare Fuse Kit
Spare Fuse Kit
One spare fuse kit used for AC or DC systems comes with the VCO/4K. The contents of the kit is
described in Table 5-1.
The two replaceable fuses on the power entry module are the main fuses, shown in Figure 5-1. One
replaceable 25-amp fuse is located on the back of the power supply module to the right of the power
connector socket.
If you choose to go from 120 VAC to 240 VAC as a result of the input power that is available at your site,
you do not need to change any fuses. The VCO/4K is an auto-ranging system.
Removal and Replacement Procedures
Caution
When you are working inside the VCO/4K system enclosure, ensure that you are ESD
protected.
Warning
Voltages present on the power backplane and at other points can produce severe,
perhaps fatal electrical shock. Observe all precautions normally associated with the
testing of electrical equipment.
Turn off power at the source before performing any service.
Removing a Nonredundant Power Supply Module
To remove a nonredundant power supply, follow these steps:
Step 1
Turn the switch off on the power entry module if the system does not contain redundant power supply
modules, or if both power supply modules are to be removed simultaneously. The power disconnect
switch is located in the rear of the system on the power entry module.
Step 2
Remove the front door of the VCO/4K system to access the power supply module.
Step 3
Connect the wrist strap to the system (upper right corner).
Step 4
Remove the two mounting screws on the front panel of the power supply module.
When the upper left screw is removed, the power is cut off from the module (the power LED is off).
If the LED is faintly illuminated red, and the interlock switch screw is removed, it is safe to remove the
power module.
Table 5-1
Contents of Spare Fuse Kit
Number of
Cartridge Fuses
Rating
Location
Four
30 amps
Power Entry Module
Two
25 amps
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Removal and Replacement Procedures
Step 5
Grasp the black hand grip on the front of the module with one hand and pull the module out. Use your
other hand to provide support underneath the module as you remove it from the system.
Removing a Redundant Power Supply Module
To remove a redundant power supply, follow these steps:
Step 1
Remove the front door of the VCO/4K system to access the power supply module.
Step 2
Connect the wrist strap to the system (upper right corner).
Step 3
Remove the two mounting screws on the front panel of the power supply module.
When the upper left screw is removed, the power is cut off from the module (the power LED is off).
If the LED is faintly illuminated red, and the interlock switch screw is removed, it is safe to remove the
power module.
Step 4
Grasp the black hand grip on the front of the module with one hand and pull the module out. Use your
other hand to provide support underneath the module as you remove it from the system.
Replacing a Power Supply Module
Caution
Follow ESD rules when replacing a system component. Use a wrist strap for grounding.
To replace a power supply, follow these steps:
Step 1
If the power supply module is nonredundant, ensure that the power is off.
Step 2
Remove the front door of the VCO/4K system to access the power supply module.
Step 3
Connect the wrist strap to the system (upper right corner).
Step 4
Grasp the black hand grip on the front of the module with one hand and use your other hand to provide
support underneath the module as you push it into its compartment.
Step 5
Fasten the two mounting screws on the front panel of the power supply module.
Step 6
Rotate the plate into position to align the left mounting screw before fastening the screw into place.
Step 7
If necessary, turn the VCO/4K system on.
Step 8
Remove the wrist strap.
Step 9
Check the power LED and ensure that the power supply module is operating. Refer to the Starting Up
the System section on page 5-1 for information on the LED.
Step 10
Replace the front door.
Caution
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Troubleshooting the Power Subsystem
Troubleshooting the Power Subsystem
There are two tasks you might need to perform when troubleshooting the VCO/4K power subsystem: Replace a fuse or fuses Replace the power supply module
Red Power LED
When an alarm is sent to the Alarm Arbiter Card and the power LED on the power supply module turns
red as a result of a voltage fault condition, you must replace the power supply module.
Power LED Is Not Green When It Should Be
If the power switch is turned on but the power LED is not illuminated (not green), either the power
supply module has failed or the power supply within the power supply module is still running (the fans
are still operating) even though the power supply module itself is not functioning. See Figure 5-3. In
either case, follow the process in listed in the Cisco VCO/4K Troubleshooting Guide to determine the
cause of the problem, which can be any one of the following conditions: A blown fuse in the power entry module A blown fuse in the power supply module A failed power supply module
When troubleshooting, you can either immediately replace a fuse or as an alternative, test it first by
checking its resistance with a meter.
The Cisco VCO/4K Troubleshooting Guide presents the process to follow when troubleshooting a single
power supply module. In a system with redundant power supply modules, both modules are load sharing;
when one of them fails, the other one takes over.
For more information about troubleshooting the VCO/4K, refer to the Cisco VCO/4K Troubleshooting
Guide.