Sony BVH-2000, Operation And Maintenance Manual

Page: 301 / 505

(5-5-3. DT-04/-05 Board)
15. V Sync Phase Detector
This circuit detects the difference (il¢ ) between the phase of the
ADV V which is from the LG board, and the
phase of the PBVX signal which has been synchronized with
the 7 MHz clock signal by the V pulse generator. Along with the
ilf data from the H sync interval comparator,
is used to
the head jump amount.
and IC5E are preset to 37 and the 7 MHz clock trequencv
is divided by 37 (or 56 by the V pulse generator in the
PAL/SECAM model). In accordance with the FIELDIFRAME
switch S2 and are preset to 186 (or 161 the
PAL/SECAM model) in the FIELD SLOW mode and to 202 (or
177) in the FRAME SLOW mode. The preset value can be finely
adjusted by switch S 1. and IC4B count down while the
REF ADV V signal is high, and the pulses are latched as the Af
into in the at
positive going edge of the PBVX signal.
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a:
ill
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a:
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ill
I
r-
LO
V SYNC PHASE DETECTOR
REF ADV V
STA RT STA RT
PBVX
IC5C-6 UE'IC5E-6)
IC3B- 3
16.
L\f,
L\¢
Adder
This circuit calculates the head jump amount required during
QrblltrQrU
ntavback from the ilf and il¢ data detected by the V
sync phase detector and H sync interval comparator. The results
of this operation are output as 8-bit data but only the high -order
3 bits are used as the actual data.
The high-order 3 bits data (JUMP STATUS A, B, C) are
suppued to the H shift selector and the shift amount is
controlled. Furthermore, these data are decoded into a decimal
value by IC2E, D/A converted by jump signal generator IC IP
and IC2F, the detected is
superimposed onto these data, and they are output to the
integrator.
Reference
should be made to the shift generator sub-
section 2 for details on the head jump amount as it relates to the
In A, and data.
A
f A DO R
SLOW: i-PITCH JUMP
SLOW:
2-
PITCH JUMP
17.
Jump Signal Generator
This circuit converts the 3-bit data (JUMP STATUS A, B, C),
which have been
from the adder and which have been
decoded into a decimal value, into an analog voltage, and it
generates
the head jump information. The head must jump
the vertical and so, when the V
pulse from the V pulse generator IC4F -13 is high, the jump
is added to the slope error signal and output to integrator
ICIN-2.
A,O.t
JUMP
SIGNAL
!--o""'K>--I-H----·::TEGRATOR
SLOPE ERROR
18. Slope Error Generator
This circuit converts the digital 6-bit data from the sync
interval counter into an analog signal. The analog signal, which
converted and is to the
one-shot IC3-0 time constant circuit in the PBVX2 detector
where is pulse-width-modulated (PWM).
The PBVX2 signal detected by this modulation at the
going edge of the PB SYNC signal input into pin 2IB. In
addition, the D /A converted
is added to the output
of the jump signal generator and supplied to integrator ICIN -2,
and the slope voltage for driving the bimorph is generated.
IC2E
1---+-----1
JUMP STATUS
DECIMAL
DYNAMIC TRACKING SYSTEM
5-5-10 BV H-2000 (U /C) IPS/PM
BVH-2180(U/C)/PS/PM