Continuous voltages higher than
264V may damage the unit.
V
OLTAGE
R
EQUIREMENTS
The USM-P operates safely and without
audio discontinuity if the AC voltage
stays within the range 88-264V, 47-
63Hz. After applying AC power, the sys-
tem is muted while the circuitry charges
up and stabilizes. After two seconds,
the On/Temp. LED on the user panel
illuminates green, the system unmutes
and is ready to pass audio signals. If
the On/Temp. LED does not illuminate
or the system does not respond to audio
input after ten seconds, consult the
Troubleshooting section.
The USM-P's power supply uses stored
energy to continue functioning for
about 10 AC cycles if the voltage
decreases below 88V (a condition known
as brownout). The precise length of time
the unit functions during brownout
depends on the operating level and how
low the voltage drops. The unit turns off
if the voltage does not increase above
88V before the storage circuits are
depleted. If the USM-P shuts down due
to brownout, the power supply automat-
ically turns on after three seconds if the
voltage returns to the normal operating
range. If the USM-P does not turn back
on after ten seconds, consult the
Troubleshooting section.
NOTE:
We recommend that the supply be
operated at least a few volts
away from the upper and lower
bounds of the operating range to
avoid possible shutdown.
C
URRENT
R
EQUIREMENTS
Each USM-P requires approximately
3Arms @115V (1.5Arms@230V) for
proper operation. This allows up to five
USM-Ps to be powered from one 15A
breaker.
The maximum burst current of the
USM-P is equal to its maximum turn on
current. For example, a loud drumbeat
which draws 3A can be easily handled by
a 20A breaker powering five USM-1Ps.
The inrush current at 230V is 50% of the
amount at 115V; the inrush current at
100V is 115% of the 115V amount.
The USM-P presents a dynamic load to
the AC mains which causes the amount
of current to fluctuate between quiet
and loud operating levels. Since differ-
ent types of cables and circuit breakers
heat up and trip at varying rates, it is
essential to understand the types of cur-
rent ratings and how they correspond to
circuit breaker and cable specifications.
The
maximum continuous RMS current
is the maximum RMS current over a
duration of at least 10 seconds. It is
used to calculate the temperature
increase in cables, which is used to
select cables that conform to electrical
code standards. It is also used to select
the rating for slow-reacting thermal
breakers.
The
maximum burst RMS current
is the
maximum RMS current over a one sec-
ond duration. It is used to select the
rating for most magnetic breakers.
The
maximum instantaneous peak cur-
rent during burst
is used to select the
rating for fast-reacting magnetic break-
ers and to calculate the peak voltage
drop in long AC cables according to the
formula below.
V
pkdrop =
I
pk x
R
total cable
Use the table below as a guide to select
cables and circuit breakers with appro-
priate ratings for your operating
voltage.
To determine the minimum total service
power required by a system of USM-P, or
other Meyer self-powered speakers, add
their
maximum continuous RMS cur-
rents
together. We recommend allowing
an additional 30% above the minimum
amperage to prevent peak voltage drops
at the service entry and nuisance trip-
ping.
P
OWER
C
ONNECTOR
W
IRING
Use the following AC cable wiring dia-
gram to create international or special-
purpose power connectors:
AC cable color code
If the colors referred to in the diagram
don't correspond to the terminals in
your plug, use the following guidelines:
• Connect the blue wire to the terminal
marked with an N or colored black.
• Connect the brown wire to the termi-
nal marked with an L or colored red.
• Connect the green and yellow wire to
the terminal marked with an E (or )
or colored green (or green and yel-
low).
S
AFETY
I
SSUES
Do not use a ground-lifting
adapter or cut the AC cable
ground pin.
Keep all liquids away from the USM-P to
avoid hazards from electrical shock.
Do not operate the unit with worn or
frayed cables; replace them immediately.
If the USM-P will be installed outdoors
contact Meyer Sound for information
about the rain hood and weather protec-
tion for the drivers and electronics.
While a single USM-P can be
hung by its handle bars and
fitted L-Track strips, do not
hang any additional weight
from the cabinet.
USM-P han-
dle bars or the L-Track strips
mounted on the top front
panel are not designed to
support heavy rigging loads.
5
V
5
1
1
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3
2
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M
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!
brown = hot
blue =
neutral
yellow/green =
earth ground
(chassis)
!
