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CHAPTER 4: Installation
4.2 The MicroRacks’ Power Supply
The power supply included with the MicroRacks uses the same mid-plane
architecture as the line-driver cards. Slide the front module of the power
supply into the MicroRack from the front, and slide the rear module in from
the rear. The two modules plug into one another in the middle of the rack.
Secure the front module with thumbscrews and the rear module with
conventional metal screws; these screws and thumbscrews come with the rack.
4.2.1 S
WITCHING THE
P
OWER
S
UPPLY
O
N AND
O
FF
The MicroRack’s power switch is located on the power supply’s front panel.
When the MicroRack is plugged in and switched on, the power supply will
light the red LED on its front panel. Since the MicroRack is a “hot-swappable”
rack, you don’t have to install any cards before switching on the power supply. Also,
the power supply may be switched off at any time without harming the
installed cards, and you can install or remove cards without turning off the
power supply. However, you should always unplug the power cord before
removing, replacing, or switching the power supply or its fuses.
4.2.2 R
EPLACING THE
P
OWER
S
UPPLY
’
S
F
USE
The MicroRack’s power supply uses a 400-mA fuse for 120-VAC circuits, and a
200-mA fuse for 240-VAC circuits. The fuse compartment is located just below
the AC socket on the power supply’s rear module. To replace the fuse, follow
these steps:
1. Making sure the rack is turned off and unplugged, use a small screw-
driver to pop the compartment open: It will slide open like a drawer.
2. Notice that there are two fuses in the compartment: The rear fuse is
“active,” and the front fuse is the “spare.”
3. If the active fuse appears to be blown, remove it from the clips and
replace it with the spare from the front of the compartment. Note the
size and rating of the blown fuse before discarding it.
4. Order a new replacement fuse. Both the 400-mA fuses (Littelfuse
®
239.400 or equivalent) and the 200-mA fuses (Littelfuse 239.200 or
equivalent) measure 5 x 20 mm.
CAUTION!
For continued protection against the risk of fire, replace blown fuses
only with fuses of the same type and rating.