Kenwood KD-600 User manual

KENWOOD
HI/FI
STEREO
COMPONENTS
KD-600
(KD-650)
NOTE: KD-600 is not provided with tonearm, shell and cartridge.
(KD-650)
QUARTZ
PLL
DIRECT
DRIVE
TURNTABLE

CONTENTS
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Note: fry
Component and circuitry: ‘are subject to modification’ to insure best
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EXTERNAL VIEW
Pea Turntable cover
(A53-02 13-12)
Hinge (2)
(J50-03 15-04)
Turntable sheet*
Turntable platter
(DO2-002 1-15)
Turntable case ass’y*
Insulator
(JO2-03 28-05)
Hinge (1)
(J50-03 14-05)
Audio cord
{E30-1333-05)
Power cord*
*Refer to Destinations’ Parts List.

INTERNAL VIEW
Hole cover plate*
Motor assy
(T43-0017-05)
Tonearm ass'y
(J91-01.18-08)
mown
Knob {1}
(K29-0650-14) a
Operation ass’y sy - =.
(D40-0451-05) ES ee] @ KENWOOD, Ste Tuitiame
Lock indicator ass‘y
(BO8-9208-04})
Power transformer*
Motor
ass'y
Power
supply
PCB
ass'y*
(T43-0017-05)
Muting PCB ass’y
(X25-1400-00)
Control PCB ass’y*
Power switch*
Operation ass’y
(D40-045 1-05)
Lock indicator ass’y
({BO8-9208-04)
*Refer to Destinations’ Parts List.

CIRCUIT DESCRIPTION
FUNDAMENTAL THEORY OF QUARTZ PLL-
TURNTABLE
As the motor structure of the KD-600 (650) is almost
identical to that of the KD-750, we will omit the description
of the motor operation of the KD-600 (650) in this manual.
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St-VSLVINS
KD-600 (650) Speed Control Block Diagram
‘not covered in detail in the manual for the KD-750.
Instead, we will provide in this manual some detailed
descriptions of the KD-600 (650)’s control circuit which was

CIRCUIT DESCRIPTION
NEGATIVE FEEDBACK THEORY
The following figure shows a negative feedback circuit
constituting a closed-loop system. Where M is a contro!
object, 8 is a feedback element: and A is an amplifier with the
gain of A.
Vout
Based on the above figure, we obtain the following formu-
la:
Vout = VAxAxM
Vin: input voltage
VA: amplifier input voltage
Vout: output voltage
VA is expressed as follows:
VA = Vin — BVout
Therefore, the closed loop gain G1 can be written as:
G1 = Vout/Vin
VAtAsM/(VA + BVASA*M)
= AeM/(1 + BA+M)
if the amplifier is assumed to be an ideal amplifier with an
infinite gain, then we obtain:
G1 = 1/6
That is, the closed loop gain is a reciprocal of 8 which is
always constant regardless of control object M.
The negative feedback is thus able to suppress unstable
factors involved in the control object by using a stabie
feedback element and ideal amplifier.
I
S-V SERVO
In conventional speed control systems, speed-information
feedback depends on a voltage proportional to the
frequency. Therefore, its closed-loop characteristic has
usually a poor linearity as shown in the following figure.
Amplifier
Vref. Turning speed
1 FG servo
Speed (w) Lene rS SSeS ess 1 circuit block
| Feedback element aingram
1/x
FG servo input-output
yw characteristic
Input (Vref)
Our KD-750 and KD-650 (600) Turntables employ not
only the S-V servo system, which is an improved version of
the conventional speed control system, but also the
phase-feedback control system. The S-V servo system uses a
Speed-Voltage converter which generates a voltage reversely
proportional to the motor’s turning speed and provides an
ideaily linear input-output characteristic.
Speed (w)
—_——w Input (Vref)
S-V Servo Input-output Characteristic
PLL
The PLL, a kind of phase feedback circuit, contro!s the
Output phase of the voltage-controlled oscillator located
within the closed loop to coincide with the phase of the
reference frequency. The following figure shows a basic
block diagram of the PLL:
This filter passes only the frequency close to the VCO frequency.
If there is any phase difference, a voltage is generated.
input
signal
Phase
;
Z
comparator
Low
pass
filter
fs
(P.C.)
(L.P.F.}
Voltage
controlled
oscillator
Vco
PLL Basic Configuration
In the above figure, the phase comparator generates a
voltage corresponding to the phase difference between the
input signal and the VCO (Voitage-Controlled Oscillator)
Output. There are an analog and digital phase comparator
now available. It is sometimes called a phase detector. The
voltage-controlled oscillator oscillates a frequency proportio-
nal to the input voltage. Its output is coupled to the phase
comparator to constitute a PLL feedback loop. The low pass
filter (LPF) in the loop suppresses harmonic components and
noises contained in the phase comparator output. The
response and synchronisation characteristic of the PLL
largely depend on this LPF characteristic.
The synchronization process taking place in the PLL loop
consists of two stages: frequency pull-in process (in which
the VCO output frequency approaches the reference
frequency) and lock-in process (in which the VCO output is
locked to the reference frequency).
:
|
1
:
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3
j
3

CIRCUIT DESCRIPTION
FREQUENCY PULL-IN PROCESS
When fs and fo in the PLL basic block diagram are
different from each other (phase difference is large), the
phase detector operates as a mixer because of its non-linear
characteristic, and generates a beat signal equivalent to the
frequency difference. If this beat frequency is below the
specific value inherent to the PLL loop characteristic, the
VCO output frequency approaches to the reference frequency
until finally the former is locked to the fatter. However, if the
frequency difference is too large, the VCO output is not
synchronized with the reference frequency by repeating
approach to and departure from the reference frequency.
The following figure illustrates the PLL synchronization
process viewed from the phase comparator output.
DC voltage of PD Phase
difference
' '
i} 4
'
i i
' Lock-in '
Pull-in
Phase Output in PLL Synchronization Process
LOCK-IN PROCESS
The frequency difference reduced in the pull-in process is
further reduced in the lock-in process until the PLL can
completely respond to the beat frequency and finally the VCO .
output is synchronized with the reference frequency.
LOCK RANGE AND CAPTURE RANGE
The PLL voltage-frequency conversion characteristic (a)
shown in the following figure indicates the case where input
frequency fs is higher than reference frequency fo. The foop
does not responds until input frequency fs reaches f1.
However, when fs reaches f1, the loop is suddenly locked to
fs and generates a negative difference voltage Vdf1 which va-
ries proportional to the reciprocal of conversion gain ko (V/-
rad) of the VCO as the frequency increases. And when fs is
equal to fo, when fs reaches f2 via Vdo, Vd rapidly returns to
zero, thus releasing the lock. It is this frequency f2 that is the
upper limit of the lock range.
Vd Oo
Out of lock
Out of
lock
<a: as input frequency fs is increased ..... >
Out of lock
<b: as input frequency fs is decreased ..... >
From the above figure, the capture range and lock range
are expressed as follows:
Capture range: f3 — f1 = 2afc
Lock range: f2 — f4 = 2aft
From the above descriptions, it may be concluded that the
PLL responds only to the frequencies apart from +afL or Afc
from the VCO output frequency fo, and when it responds, the
PLL ts locked in.
4
|
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CIRCUIT DESCRIPTION
QUARTZ LOCK PLL
QUARTZ
Block Diagram for Quartz Lock PLL.
From the above figure, it is known that the control circuit
is Composed of three basic closed loops: the inner-most
constant current loop constituting the motor driver section,
the outer S-V converter closed loop to control turning speed,
and the outer-most phase-comparator closed loop to control
phase. The quartz crystal controlled oscillator oscillating the
reference frequency for the phase comparator provides a
higher precision motor control.
OPERATION CONTROL SECTION
When turntable operations, such as start, stop and speed
change, operating mechanisms in conventional turntables
have given undesirable vibrations to the turntable. In order
to eliminate such unnecessary vibrations, the KD600 (650)
Turntable has incorporated “touch” switches into its
Operating section.
The following diagrams cover some technical descriptions for
an integrated circuit (IC) designed to aid the touch switch
operation.
The SAS-560S, a monolithic IC designed to aid the touch
switch operation, requires only a very small operating .cur-
rent. lt has four independent inputs, and two outputs cor-
responding to each input. The following table shows the pin
configuration of the SAS-560S.
Channel Application
STOP
45 rpm
33 rpm
Pin numbers enclosed in a circle indicate those for turning-speed display
output.
SAS-560S IC Pin Configuration
TOUCH SENSOR (SAS-560S)
This
IC
includes
4
control
circuits
as
shown
in
the
diagram
below.
(Refer
to
page
18.)
The point 14 is the sensor input which is normally biased
by +B through 560 kQ, turning Q202, A203, 0206, Q207,
Q210-Q215, Q208 and 0208 to OFF and 0204 and Q205
to
ON,
so
no
voltage
is
present
at
the
points
13
and
4.
By touching the sensor input 14, a current flows through
4.7 MQ, turning Q202 to ON which, in turn, turns Q204 and
Q205 to OFF and Q206, 0207, Q210-Q215, Q208 and
Q209 to ON, so that an output voltage is developed at the
point 13 and 4.
By releasing the sensor input 14, Q202 and Q203 turn to
OFF and Q204 and 0205 turn to ON; Q206 also turns to
OFF, while Q207 is locked in ON state by Q208 and Q209 (a
positive feedback loop is formed by Q207, Q208 and
Q209). Since Q210-Q215 remain ON, the output voltage ts
still present at the points 13 and 4 when the sensor input is
released. These circuits can be unlocked by increasing the
voltage at the point 2.
Q206, Q207, Q106, Q107, Q306, Q307, 0406 and
Q407 each are connected to a common emitter with an ex-
ternal load resistor, so when any one of the 4 circuits is lock-
ed, the remaining circuits are unlocked because the voltage
at the point 2 is increased.
There are no possibilities of locking more than one Circuit
at the same time (see the circuit diagram of SAS5608S, P18).
When the power is ON, the output voltage is first
developed at the points 6 and 9 since Q507 and Q508 are
momentarily turned ON through the circuit Q504-Q508
which functions as a start switch. As the emitter of Q508 is
connected to the base of Q408, 0408 turns ON which, in
turn, locks Q407, 0408 and Q409 in ON state.

CIRCUIT DESCRIPTION
13 indicator
output
+8
© 4 output
Channel-1
in
the
IC
incorporates
a
power-set
(initializing)
of
pin-5
and
pin-6
are
used
for
turning-speed
selection
sig-
circuit
which
resets
the
entire
turntable
mode
into
the
STOP
nal.
Outputs
pin-9
and
pin-11
are
coupled
to
transistors
mode
when
the
power
of
the
turntable
is
turned
on.
The
Q15
and
Q16
respectively
which
drive
turning-speed
output
of
pin-9
is
used
for
stop-operation
signal,
while
those
indicator
LEDs.
At 45 rpm, the LED (45) lights
with Q16 turned OFF and Q15
turned ON.
Set to “H” in the STOP mode.
At 45 rpm, this output is set to "H”.
At 33 rpm, this output is set to “H”.
None of the LEDs for 45
and 33 rpm lights with Q15
turned OFF.
At 33 rpm, the LED (33)
lights with both Q15 and
Q16 turned ON.
~t----- ------}
Turning-speed Indicator LED Drive Circuit
SPEED-MONITORING CIRCUIT
To brake monitor
Set to “H” in the STOP
mode or at 45 rpm.
Set to "L” at the
correct turning speed.
As the turning speed decreases, the output
voltage goes higher; as the turning speed To power indicator
increases, the voltage goes lower. To lock indicator
|

CIRCUIT. DESCRIPTION
The Speed-Monitoring circuit monitors motor rotation for
correct turning speed. The outputs of the circuit become the
control signals for the power indicator, lock indicator, and
brake-monitor circuit. Pin-8 of IC8 accepts the voltage from
IC1 and the FG signal, which is S-V converted and passed
through a low-pass filter, proportional to motor rotation. IC8
is an analog level comparator, i.e. an A/D converter, of which
logical output pins 2, 3 and 4 are connected to each logic
circuit. The input/output characteristics of the 5-step analog
level comparator is shown in the following table:
Analog Input
Motor Rotation
Terminal 8 :
Turning speed
too high
<200mvV
Correct turning
speed
200 ~ 400mV
400 ~ 600mV
600 ~ 800mV Turning speed
800 ~ 1000mV age low
Lock indicator}
Power indi-
cator
No connec-
Output Applica-
tion
* Turning speed of less than 0.144 rps (brake signal is released)
Input/Output Characteristics of the 5-step
Analog Level Comparator
The input, pin-8, of the analog comparator is adjusted with
trimming potentiometer VR1 and 2 so that the output, pin-4,
is “'H”’ with the correct turning speed and that is ’L” with less
0.144 rps. Together with this input voltage adjustment,
brake turn-off timing (to eliminate the brake control signal) is
also adjusted. (Refer to the “Brake Monitor Circuit’’.)
LOCK INDICATOR CIRCUIT
The Lock Indicator circuit drives the lock indicator lamp
when the motor is locked to the correct turning speed with
the constant phase difference. The circuit requires four
different input signals to drive the indicator as illustrated
-below:
10
Set to “L" at the correct Lock
turning speed.
From the level
comparator
When the motor is turning at the correct turning speed,
inputs A and B in the above figure are set to “L” and “H"
respectively. Pin-9 of IC3 set to ’L’. Meanwhile, pin-8 of IC3
accepts a square wave and the square wave causes the
output level of pin-10 to repeat ’H” and “‘L”’ alternately. As a
result, the lock indicator lamp, driven by transistor Q18, is
“dynamically” lit. Actually the lamp blinks, but the blinking
periode is so rapid and the illuminance level is so constant
that it appears as if the lamp constantly lights.
Now let us think of the input signal to pin-8 of IC3. When
the motor starts turning, an FG signal is applied to the clock
input of IC5, and a signal S-V converted from the FG signal is
applied to its reset terminal via Q11 and inverter IC7. Then
the O output of 1C5 is connected to pin-8 of IC3. The clock
input of IC5 accepts a square wave while its reset terminal
accepts a pulse signal as shown in the following timing
chart:
Input JH
Input K H
L
. H
Clock input L
Reset terminal : |
H 4 ; - : 3 ‘ e a
L
Constant
Integrated
value
period.
Output O
*
When
both
the
J
and
K
inputs
are
pulled
up
to
““H”
level,
every
clock
input
triggers
the
output
into
the
reverse
state.
Output O of IC5 is connected to pin-2 of IC3. As a result,
an inverted square wave is obtained on output pin-3 of IC3
since the other input pin-1 of IC3 is always set to “’L” in the
PLAY mode. Pin-8 of IC3 accepts the square wave via
inverter [C7 and its output pin-10 repeats ‘"H” and ‘’L” alter-
nately as described previously.
The following figure illustrates what happens if the FG sig-
nal has an trreguiar period:
Lamp drive
voltage
Integrated value (@)
FG signal (implies irregular motor rotation)
Reset pulse (with constant period)
Q output waveform
Since the period of reset pulse is not regular, the lock indicator
appears to be blinking (jock is “out’’).
©8680
Lock Indicator Operation with Irregular FG Signal