Black Box MT160A Manual page 40

3) Note that there are two fuses in the drawer. The front fuse is the spare,
and the rear fuse is the "active" fuse.
4) If the active fuse appears to be blown, remove it from the clips and replace it
with the spare from the front compartment. Note the size and rating of the
blown fuse before discarding it.
5) Buy a replacement fuse at an electronics store. (Note: For continued
protection against the risk of fire, replace only with the same type and
rating of fuse.)
Switching the Power Supply Between 120 and 240 Volts
The power supply module should be installed in the rack chassis before any
CSU/DSU cards. Here are the steps to select the switch for the proper voltage
level.
1) Locate the two-position switch near the back of the card. Slide the switch to
the desired voltage. (Note: The actual values on the switch may be "110/220"
or "115/230.")
2) Verify that the existing fuse is the correct value (400 mA for the 120-volt, 200
mA for the 240-volt).
3) Connect the power supply cord.
Wiring the MicroCSU/DSU
Each of the rear interface cards compatible with the MicroCSU/DSU has one
terminal interface port and one 4-wire (twisted pair) port. For specific interface
pinouts, refer to Appendix B.
Operating the Power Supply
The AC power supply has a single power LED on the front panel, which lights
when the power switch is turned on and the unit is connected to an AC power
source.
The DC power supplies feature two front-panel LEDs that indicate the condition of
the power line. The "Power " LED will only light when the power switch is turned
on and the low voltage AC power is available to the function cards installed in the
rack. The "DC Input" LED will light whenever a power source is present (with
correct polarity), regardless of whether or not the power switch is turned on.
CHAPTER 5: Installation
37