13
Powering and Mounting
Both an AC mains source and a DC source can be
connected at the same time. The AC mains source will
power the MD-4 with the DC source serving as a “hot
standby.” If the AC source fails the unit will draw power
from the DC source automatically with no interruption of
MD-4 operation. The MD-4 draws less that 100 micro-
amps (uA) from the DC input when an AC mains source
is connected.
Note: During the first few seconds after
the unit powers-up mechanical clicks may
be heard from the MD-4. This is normal
and is a function of the input attenuation
circuitry’s latching relays being set.
Powering On
The MD-4 begins its power-up sequence as soon as
power is connected. As an integrity check all the meter
LEDs, status LEDs, and numeric display digits will light
in a test sequence. This takes approximately five sec
-
onds and will be followed by the application firmware’s
(embedded software) version number being displayed
on the numerical display for about one second. Full
MD-4 operation will depend on the establishment of
Dante connectivity.
When power is removed all the MD-4’s operating
parameters are saved in non-volatile memory. All
settings, including gain, phantom power, and high-pass
filter state, will be restored at the next power-up cycle.
Also at power up the status LEDs on the back panel will
light in various manners. The status LED located below
the USB connector will flash once to confirm operation.
The two Dante and one network status LEDs, located
below the etherCON RJ45 connector on the back panel,
will light as Ethernet and Dante network performance
begins.
Rack Mounting
The MD-4 requires one space (1.75 vertical inches or
1U) in a standard 19-inch (48.3 cm) equipment rack.
Secure the unit into the equipment rack using four
mounting screws, two per side.
The rack-mounting brackets (“ears”), located on the
sides of the MD-4’s enclosure can be removed to
assist in achieving special mounting or installation
requirements.
Powering the MD-4
The MD-4 requires either AC mains or DC power for
operation. Both can also be simultaneously connected if
redundant (backup) power is desired.
AC Mains Power
The MD-4 operates from AC mains power, 100-240
volts, 50/60 Hz, 15 watts maximum. A 3-pin IEC 320
C14 inlet connector on the back panel mates with a
detachable mains cord set.
The MD-4 ships with an AC mains cord with a North-
American (NEMA 5-15L) plug on one end and an IEC
320 C13 connector on the other end. This cord is
suitable for use in North America and Japan. In other
locations consult your reseller or distributor for a suit-
able AC mains cord. The wire colors in the mains cord
should conform to the internationally recognized color
code and be terminated accordingly:
Connection
Wire Color
Neutral (N)
Light Blue
Line (L)
Brown
Earth/Ground (E)
Green/Yellow
Because the MD-4 does not contain a power on/
off switch it will begin operation as soon as power is
connected.
Safety Warning
: The MD-4 does not
contain an AC mains disconnect switch.
As such, the AC mains cord plug serves
as the disconnection device. Safety
considerations require that the plug and
associated inlet be easily accessible to
allow rapid disconnection of AC mains
power should it prove necessary.
DC Power
The MD-4 can operate from a stable DC power source
of 10 to 18 volts DC. The current required from a 12
volt DC source is 1.1 amp maximum. A 4-pin male XLR
connector, located on the unit’s back panel, is used to
connect the source of DC. Prepare a mating connector
(female) so that pin 1 is – DC and pin 4 is +DC. Pins 2
and 3 are not used and should remain unconnected.
This connector type and pin-out are rapidly becoming a
broadcast DC power standard and should be familiar to
many technical personnel. Because the MD-4 contains
no power on/off switch it will begin operation as soon
as a DC power source is connected.
