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DP-7020
CIRCUIT DESCRIPTION
Part. No.
Use/Function
Operation/Condition/Compatibility
2SA1534A
Buffer
2SC3940A
Drive feed motor.
| 2SA1534A,
Buffer
Drive actuator of tracking.
2SC3940A
| 2SA1 534A
Buffer
2SC3940A
Drive actuator of focusing.
2SA1534A
Buffer
2SC3940A
Drive disk motor.
2SA11534A,
Buffer
For laser diode and ALPC.
2SC1740S (Q, R) | Switch
2SC945 {A) {Q, R}
When focus servo is on FE BIAS circuit works.
2SC3666
Buffer
2SA1426
1-2. DISPLAY AND 1:-COM UNIT (X25-3810-00)
Part. No.
Use/Function
IC1~3
TD62801P
Inverter
1C4
PD7S216ACW-295
| Microprocessor
=
iC5
M51951ASL
Reset [C
2$C€1740S (Q, R)
2SC945 {A) (Q, R)
For head phone.
Operation/Condition/Compatibili
Convert data (Serial
For reset of microprocessor.
Buffer
For FL-indicator of pin1 and pin9.
OTA124EN
Buffer
For VOLUME LED.
parallel). For 20KEY LED.
DTA124EN
Power supply
2. Display unit p-com unit
«Turning on the seif-illuminating 20KEY LED's
The self-illuminating 2OKEY LED's are turned on with
the 8-bit shift register (TD62801P). The microprocessor
sends the serial data, latch data, and clock to turn onthe
20KEY, PLAY, and PAUSE LED's.
Three units of TD62801P are used and connected
respectively by S-OUT and S-IN. The data are output by
setting the enable terminal to "H" level.
Fig.1 shows the rough block diagram for turning on
the LED's and Fig.2 shows the timing chart.
SIRIAL DATA
LATCH
DATA
TD6280IP
Fig. 1
12
For reset IC.
RESET
CLOCK
S-IN
CATCH
S-OUT
DP-7020
CIRCUIT DESCRIPTION
* D.P.A.C (Digital Pulse Axis Control) circuit
Two different distortions are attendant on the con-
version of the digital signal into an analog signal. One is
a distortion on the level axis (voltage axis), which is
determined mainly by the resolution of the D/A con-
verter, and in case of using a ladder resistor type, by its
error.
The other is a distortion on the time axis, which is not
so prevailing
as to appear on the distortion meter but has
great influence on the sound quality. It is the D.P.A.C
that is to operate as a circuit to improve this point.
e———--—@
Original Sound
Regenerated
Waveform
Fig. 3
Error (distortion) on voltage axis
¢ D.P.A.C by sample holding (S-H) circuit
The model of this time has the D.P.A.C circuit on
the basis of an S-H circuit which has been more im-
proved than the conventional D.P.A.C.
This new S-H circuit has the same composition as
the conventional one. The difference between them
is that the former uses the clock obtained by dividing
the master clock for the sample holding signal which
does not have jitters. This clock is converted into an
analog signal, than its time axis corrected (its jitters
are eliminated). The D/A conversion is carried out at 8
FS, but the sample holding clock is set to 16 FS. Ac-
cordingly , the noises generated in the S-H circuit is
raised to 16 FS, thus the effects on the audio signal is
minimized.
Figure 2-3 shows the error (distortion) on the voltage
axis of the D/A converter output for the original sound,
and Figure 2-4 shows the error (distortion) on the time
axis of the D/A converter output for the original sound.
As seen from this, even with a variation in time axis,
there appears a regenerated waveform different from
the original sound.
e—————@
Origino! Sound
yy
Regenerated
x
Waveform
Fig. 4
Error (distortion) on time axis
13
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