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Circuit Breaker
A 16 amp circuit breaker on the rear panel
protects the amplifier's electrical circuity.
Generally, the circuit breaker will only open
under a fault condition which results in exces-
sive current draw. To reset the circuit breaker,
press the button. Should it repeatedly open,
contact your authorized Rotel dealer for
troubleshooting assistance.
Protection Indicators
A thermal protection circuit protects the ampli-
fier against potential damage in the event of
extreme or faulty operating conditions. Unlike
many designs, the RKB-650's protection circuit
is independent of the audio signal and has
no impact on sonic performance. Instead, the
protection circuit monitors the temperature of
the output devices and shuts down the ampli-
fier if temperatures exceed safe limits.
In addition, the RKB-650 includes overcurrent
protection which operates only when load
impedance drops too low.
Should a faulty condition arise, the ampli-
fier will stop playing and one or more of
the PROTECTION LEDS on the front panel
will light.
If this happens, turn the amplifier off, let it
cool down for several minutes, and attempt
to identify and correct the problem. There are
independent PROTECTION LEDS for each pair
of channels which may help in troubleshoot-
ing the cause of 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 acti-
vates because of a fault condition such as
shorted speaker wires, or inadequate venti-
lation causing an overheating condition. In
very rare cases, highly reactive or extremely
low impedance speaker loads could cause
the protection circuit to engage.
9
Signal Connections
The RKB-650 provides standard conventional
input connections — unbalanced RCA type
connections as found on nearly all audio
equipment.
There is also a pair of SIGNAL OUTPUT
LINK connections for passing the input signal
connected to the "A" pair of channels on to
another audio component. Additionally, the
input signal to the "A" pair of channels can
be automatically linked to the inputs for the
"B" and/or "C" channels, so that a separate
input signal cable is not required for those
channels, for example in large systems where
the RKB-650 is being used to drive multiple
pairs of speakers.
RCA Inputs
See Figure 2
There are two RCA inputs for each of the
three pair of amplifier channels. These RCA
inputs accept audio signals from preampli-
fiers or surround sound processors. Use high
quality audio interconnect cables for best
performance.
For each pair of amplifier channels, connect
the left channel output of your preamp to the
LEFT INPUT on the RKB-650. Connect the
right channel of your preamp to the RIGHT
INPUT. Make sure that the input slide switch
to the right of the RCA inputs is in the STE-
REO position.
Linking the Inputs
You can link the inputs for groups "B" and/
or "C" to the "A" inputs by placing the input
slide switch to the right of each pair of RCA
inputs in the LINK position. When linked, no
input connection is required for that group.
The input signal from the "A" group is sent
to the linked pair of channels, allowing you
to use four or six amplifier channels with the
same stereo input signals.
Input Level Controls
Three controls on the front panel, one for each
pair of channels, provide input level adjust-
ments. These allow you to adjust the gain of
the amplifier to match other components in
the system. The A level control changes the
gain of the "A" channels; the B level control
changes the "B" channels; the C level control
changes the "C" channels.
To adjust these controls, use a small, flat-
blade screwdriver. Turn the control clockwise
to increase gain. Turn counterclockwise to
reduce gain.
For easier adjustment, install the supplied vol-
ume control knobs by gently pressing them
onto the control shafts. Alternatively, you can
prevent inadvertant adjustment by installing
the supplied rubber plugs to conceal the vol-
ume controls.
Signal Output Link
This pair of RCA connections can be used
to pass the unprocessed input signals to
another audio component, for example to
"daisy-chain" an additional amplifier to drive
a second set of speakers. The input signals
connected to the "A" channels is also avail-
able at these LINK outputs.
: These input signals from the "A" chan-
NOTE
nels can also be linked to the "B" and/or "C"
inputs by playing the INPUT SELECT switch
associated with that pair of channels in the
LINK position.
English
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