Akai VS-2EGN

During
CUE/REVIEW
and
PB/PAUSE,
the
V
pulse
generated
by
the
switching
pulse
is
injected
into
the
servo
circuit
to
prevent
shaking
in
the
Vertical
direction
on
the
TV
screen
due
to
omission
of
V
SYNC
com-
ponent.
Subsequent signal flow is omitted since it is the same as
the E-E system.
2-2
CHROMINANCE
(CHROMA)
RECORDING
AND
PLAYBACK
SYSTEM
REC CHROMA IN
fs= 4.433619MH2
+
NTSC 40f'H= 629,37056KHz
> LOW FREQVENCY CONVERTED
4)
PAL
fs¢(40+1/8)fH=5,060572IMHz
DELAY
ICI! AN6321
=
2 FLI4
LPF_OUT.
5.06BPF
p-com }—>{ vxo }->|
1} + hal —_-----—
1Cl2 AN6342N
cee a
| x0 @— xl
|
Tee
x2 X1,2. 1 4.433619MHz
PAL (40+1/8)tH=626,953I2KHz
NTSC
fs+40¢ w= 5.06298956MHz
f=15625Hz (PAL BG)
fu =15734,264Hz (NTSC)
Fig. 7-9 CHROMA Recording/Playback Block Diagram
2-2-1 RECORDING OF PAL B/G AND NTSC 4.43
The input video signal already described in the section
devoted to the luminance E-E system separates into a Y
signal path through FL3—S5, and a path for the
CHROMA signal having the frequency band 4.43 MHz+
500 kHz. It alone passes through FL16 (LCB-57) and
BPF (3.68 MHz—5.18 MHz at —3 dB point). (The Band-
width and center frequency of PAL B/G CHROMA sig-
nals are the same as those of NTSC 4.43 CHROMA sig-
nals). The CHROMA signal is fed to IC10 (AN6360)
pin ©. Since the internal switch is in the recording
mode, the signal is output from pin , and reinput
from pin During the PAL mode, 5.0605721 MHz
enters pin . The output of pin @) becomes a 626.9
kHz low frequency CHROMA signal as it passes through
FL14. During the NTSC 4.43 mode, 5.0629895 MHz
enters pin (4), and the output from pin (2) passes
through FL14, and is output as a 629.3 kHz low fre-
quency CHROMA signal.
At this time, the APC system is actuated to lock the
phase burst of low frequency converted CHROMA to
that of input CHROMA signal.
During the NTSC 4.43 mode, 4N-H becomes ‘H’, actuat-
ing TR47 through D20. 40 fH from IC9 (AN6362) pin
O is selected, which causes IC10 (AN6360) pin (S) to
become ‘L’ via the inverter (TR52). Only the burst com-
ponent is amplified by 6 dB after the balanced modulat-
or.
(In the case of the PAL mode, the burst is not amplified
due to IC10 pin S)being ‘H’.)
18
1) NTSC phase shift
IC9 pin @ is driven by the switching pulse from the
servo circuit, and +90° phase shift is effected at every
horizontal period when this is ‘H’. That is, the switching
pulse gives +90° phase shift during CH-1 period if ‘H’
time is CH-1. Since pin (1) is ‘L’ in every CH-2 period,
—90° phase shift is effected.
2) PAL phase shift
IC8 (AN6363) pin ® is a control input pin to cause
that CH-1 (‘H’ period) does not have any phase shift ir-
respective of the horizontal period while CH-2 (‘L’
period) makes —90° phase shift at every horizontal
period. It carries out the above operation by using the
switching pulse as the input.
3) Mixing of FMY signal
Low frequency converted CHROMA signal from IC10
pin (2) passes through FL14 (1.5 MHz at —3 dB point),
enters pin ®, is amplified, switched to the recording
side by the REC/PB switch, is output from pin(?),p as-
sed through the 4.47 MHz trap composed of L4 and
C10, level-adjusted at VR2, mixed with the FMY signal,
and supplied to the pre-amp through the emitter follow-
er.
(Subsequent signal flow is omitted since it is described
in the section devoted to the Y recording system.)
Service
Manual
VS-2EGN
———_—_$-A___
<>