Kenwood KR-6030 Service Manual

4
i
CIRCUIT DESCRIPTION
DC DETECTION
The relay is released when DC voltage appears at the out-
put terminals. Thus the loudspeaker system can be protect-
ed. When positive (+} potential is generated at the output
terminals, Qe19 is turned on to turn off Qe21 and Qe22,
and the relay is released. When negative (—) potential
appears at the output terminals, Qe18 is turned on to turn
on Qe20. This causes Oe21 and Qe22 to turn off, and
the relay to be released.
MUTING OPERATION FOR AM
+Vcc
Relay
AM signal line
Signal short-
circuited to GND)
Transistor Qg6 composes an AM muting circuit. When
the selector switch, Sg1, is set in the FM position, +14 V is
applied to the anode of Dg3. Then voltage is applied to.the
base of Qg6 to turn it on. The AM signal is transferred to
the GND circuit and the tuner output cannot be fed to the
preamplifier. In the AM position, voltage to the base is
applied from the —50 V and Og 6 is turned off. The signal
is then fed to the preamplifier. When the power switch,
S1, is turned off while the selector switch is in the AM
position, there may be a signal leakage.
To avoid it, the AM signal is transferred to the GND circuit
simultaneously when the power switch is turned off. When
the
power
switch
is
off,
the
relay
driving
transistor
Qe21
is also off and the collector potential is raised as a result.
This potential is applied to the base of Qg6 through Rg82,
and the AM signal is led to the GND circuit as described
previously.
MUTING OPERATION FOR FM
+14V during
+18V the FM position
| +B for the FM
| front end circuit
I and ICg3
\Cg1 Rg78
No. 12
terminal
Dgs 12 (switch)
Y \cg3 Qg
' No. 10
ICg3 terminal
No. 11
terminal
Qg8 | Qg9 |0g10] Qg12 (switch)
short-circuit
The
schematic
is
an
FM
muting
circuit,
which
is
controlled
by
No.
12
terminal
voltage
of
IC
HA1137W.
Voltage
at
No.
12
terminal
is
0
volt
during
tuning
and
0.8
volt
during
detuning.
When
Qg8
is
turned
off,
+B
is
applied
to
No.
11
terminal
of
ICg3
to
stop
the
stereo
operation.
Qg10
is
turned
on
a
few
seconds
after
switching
over
from
the
other
function
to
FM.
This
is
controlled
by
a
delay
circuit.
During tuning
During detuning

Kenwood KR-6030 Specifications

Amplifier Section

power output	80 watts per channel
total harmonic distortion	0.1% at rated power into 8 ohms
intermodulation distortion	0.1% at rated power into 8 ohms

Power

power consumption	600 W at full power
dynamic power output	340 W
maximum input level for phono	250 mV (RMS), T.H.D. 0.1% at 1, 000 Hz

Weight and Dimensions

weight	30.9 lbs (14.0 kg)
gross weight	35.2 lbs (16.0 kg)
dimensions	W 18-29/32" (480 mm), H 5-7/8" (149 mm), D 15-15/16" (405 mm)