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AC Power and Control
AC Power Input
The RB-976
is supplied with the proper AC
MkII
power cord. Use only this cord or an exact
equivalent. Do not use an extension cord. A
heavy duty multi-tap power outlet strip may
be used, but only if it is rated to handle the
current demand of the RB-976
Be sure the power switch on the front panel
of the RB-976
is turned off. Then, plug one
MkII
end of the cord into the AC power connector
on the back panel of the amplifier. Plug the
other end into an appropriate AC outlet.
Your RB-976
is configured at the factory
MkII
for the proper AC line voltage in the country
where you purchased it (USA: 115 volts/60
Hz , Europe: 230 volts/50 Hz). The AC line
configuration is noted on a label on the back
panel.
: Should you move your RB-976
NOTE
another country, it is possible to configure your
amplifier for use on a different line voltage.
Do not attempt to perform this conversion your-
self. Opening the enclosure of the RB-976
exposes you to dangerous voltages. Consult
a qualified technician or the Rotel factory ser-
vice department for information.
If you are going to be away from home for
an extended period of time, it is a sensible
precaution to unplug your amplifier.
Power Switch and Indicator
The power switch is located on the left side
of the front panel. To turn the amplifier on (or
to activate either of the optional automatic
power-on modes), push the switch in. The LED
indicator above the switch will light, indicat-
ing that the amplifier is turned on. To turn the
amplifier off, push the button again and re-
turn it to the out position.
9
Auto Turn On/Off Mode
Selector
The RB-976
manual or automatic power on/off operation.
These modes are selectable using a three-
position slide switch on the back panel:
• With the switch in the OFF position,
the amplifier is turned on or off manually
using the front panel power switch. Use
.
MkII
this mode if you are using a switched AC
outlet to control power to the amplifier.
• With the switch in the SIGNAL SENS-
ING position, the amplifier turns on au-
tomatically when a signal is sensed at the
inputs. The amplifier will go into standby
mode after five minutes with no signal. The
front panel power switch overrides this func-
tion. It must be ON for the signal sensing
to work. Turning the switch OFF cuts power
to the amplifier, regardless of whether or
not a signal is present.
• With the switch in the +12V TRIG.
to
MkII
IN position, the amplifier is turned on
automatically when a 12 volt trigger sig-
nal is present at the screw terminals adja-
cent to the left of the switch. The amplifier
MkII
will go into standby mode if the +12 volt
signal is not present. The front panel
POWER SWITCH overrides this function.
It must be ON for the +12V trigger to work.
Turning the switch OFF cuts power to the
amplifier, regardless of whether or not a
trigger signal is present.
+12V Trigger Input
A pair of screw terminals for connecting the
wires carrying a +12 volt trigger signal to turn
the amplifier on and off, such as might be used
in a custom installation. To use this feature the
adjacent slide switch must be placed to the
left position (see previous section).
The TRIGGER INPUT accepts any control sig-
nal (AC or DC) ranging from 3 volts to 30 volts.
The screw terminals are labeled "+ and –"
Observe proper polarity when connecting the
trigger signal wiring.
Protection Indicators
Thermal and protection circuits protect the am-
plifier against potential damage in the event
of extreme or faulty operating conditions. Unlike
many designs, the RB-976
cuit is independent of the audio signal and
provides three options for
MkII
's protection cir-
MkII
has no impact on sonic performance. Instead,
the protection circuit monitors the temperature
of the output devices and shuts down the am-
plifier if safe limits are exceeded.
In addition, the RB-976
includes overcurrent
MkII
protection which operates only when load im-
pedances drops too low. This protection is in-
dependent for each of the three pair of chan-
nels with separate front panel PROTECTION
LEDS for each.
Should a faulty condition arise, the amplifier
will stop playing and one or more of the PRO-
TECTION LEDS on the front panel will light.
If this happens, turn the amplifier off, let it cool
down for several minutes, and attempt to iden-
tify and correct the problem. When you turn
the amplifier back on, the protection circuit
will automatically reset and the PROTECTION
LEDS should go out.
In most cases, the protection circuitry activates
because of a fault condition such as shorted
speaker wires, or inadequate ventilation lead-
ing to an overheating condition. In very rare
cases, highly reactive or extremely low imped-
ance speaker loads could cause the protec-
tion circuit to engage.
Stereo/Bridged Mono
Mode Selection
It is useful to think of the RB-976
stereo amplifiers in a single chassis. Each of
the three pair of amplifier channels can be
operated in Stereo or Bridged Mono mode.
• Stereo mode: Conventional 2-channel
stereo operation for a pair of amplifier
channels. Minimum speaker load: 4 ohms.
• Bridged Mono mode: Bridged Mono
mode more than doubles the power into
a single speaker. Minimum speaker load:
8 ohms.
The two modes are selected by three rear panel
switches, one for each pair of channels. Ste-
reo or Bridged Mono configuration is inde-
pendent for each pair of channels. You can
configure some pairs of channels in Stereo
mode and others in Bridged Mono mode.
English
as three
MkII
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