Circuit Description - Kenwood KA-1100D Service Manual

KA-1100D
CIRCUIT DESCRIPTION
Control Unit (X11-2280-81)
Ref. No. Application/Function Operation
IC1 . Tone control circuit IC
Qi Lamp constant voltage, circuit Keeps the voltage applied to the lamp at 27 voits.
t
Q2,3 Winking circuit
The LED lights up when the power display and set are operating properly. The LED
flashes during the 5-second interval between the time the power is turned on and when
the amplifier stabilizes. The LED also flashes if the main amplifier is not working
properly and the protection circuit has been activated.
New VIG DLD Circuit
1. Features
As the successor model! to the KA-1100SD, the KA-1100D
retains the rich array of functions available on the
KA-1100SD, making the KA-1100D the perfect amplifier
for a sophisticated model like the KA-990V. The
KA-1100D incorporates new technology appropriate for
an up-market integrated amplifier, such as:
1. Anew VIG DLD (Dynamic Linear Drive) circuit
2. Adual phono equalizer
3. Adual REC OUT switch
2.A New VIG DLD Circuit
Refer to the KA-990V new-product data for an explanation
of the principle on which VIG operates.
The configuration of the VIG circuit incorporated in the
current KA-990V is depicted in Figure 1.
In addition to preventing the influx of undesirable power
source components (such as ripples) into the Q1 driver
transistor, the VIG circuit also applies a bootstrap to the
output as shown in Figure 1A. The output from the VIG
then follows the output from the amplifier in a constant
voltage shift pattern. The input signal is no longer ab-
sorbed by the power source according to the potential
which exists between the input and the power, and high-
frequency characteristics and distortion rates are im-
proved.
Power source
Q2 final
transistor
Driver
transistor
Figure 1 Configuration of a Conventional VIG Circuit
As a result, the voltage across the output of Q1 (the emit-
ter) and the power source (the collector) is held constant
whether or not there is a signal (see Figure 2).
This insertion of a VIG circuit in the initial stage of a Darl-
ington connection circuit means that undesirable power
source components do not undergo current amplification
at Q2, the final transistor. In other words, large-capacity
power sources free of ripples become the norm.
Power source
eet eee eee tet et Sth he
Amplifier
Ripple-free power at constant voltage
Figure 2 VIG Output and Amplifier Output
Constant
voltage
TaN Voltage shifts
according to Q1
Q2 base emitter —_Intervailic
voltage (shifts)
Figure 3 VB-E and VIG Output