Sony BVH-2000, Operation And Maintenance Manual

Page: 295 / 505

5-5-3. DT-04 Board (DT-05 Board in PS model)
1. Outline of Digital Trace Circuit
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While the arbitrary playback, the DT head either skips the video
tracks tracks
overlapping (overlap tracing), and every time the tracing of one
completed, the as to track should be
traced next is controlled by the digital tracing control section.
The control section is as follows.
H SYNC INTERVAL COUNTER
V SYNC PHASE DETECTOR
ADDER
The of the DT head with respect to the tracks
is selected by the data (Af, ~¢) from these circuits.
As a result, a is output to the H shift selector as the
"JUMP STATUS" signal and the DT V phase, as the
information of the playback picture, is controlled.
Furthermore, the '"JUMP STATUS" converted
and superimposed onto the bimorph drive signal (ORE) so that
the head will jump the tracks.
In the case of the PS model, the '"JUMP STATUS" signal is
encoded and output as the
to the TBC in order to maintain the continuity of the burst
of has
This detects the writing speed
(Af)
of the recording tracks and
head
The PB H signal from the DM board is waveform-shaped
and
divided PB H signal cycle is measured by the 7 MHz clock
The time difference between the REF ADV V signal from the
signal is sampled by the 7 MHz clock signal, and the phase
(~¢) of video is
Ut::lt::Llt::U.
This processes the tape speed data (Af) and the phase data
it determines the amount in accordance
with the results obtained.
DYNAMIC TRACKING SYSTEM
2. FHX Doubler
Input into pin 46B on the DT board is the H period FHX signal
with of 50%. This is with the
playback video signal, which has been stabilized to a high
the AFC circuit and which has been svnc ..separated
from the playback video signal at the TBC.
One-shot IC5K-5 is
at the positive going edge of the
FHX signal and IC5K-l3 is triggered at the negative going edge,
and the 2FHX signal, produced by doubling the
FHX signal, is output from the NOR gate IC5J-IO.
FHX
468 : FHX
IC5K-5
IC5K-13
IC 5J
-10:
2FHX
3.
stable sync
separating it from the playback video signal in the TBC, is input
to detect V)
during arbitrary playback. Furthermore, it is reset by the V
and
is also aligned. When the DT head jumps a track, a 2.5H (or
Consequently, one field interval is counted by the counter
this
is divided into the interval during which the DT head traces the
the
track upon completion of the tracing.
tracks,
2FHX signal is counted up to 505, which is equivalent to 252.5H
602, to 30lH, the the counter
IC 51,5H, and while the count is taking place, the H shift selector
IC SF is
from When the 505 count is
completed and it is the turn of the head jump interval, the
output shift of the shift selector IC 5F is selected
by the JUMP STATUS A, Band C signals in 2.5H steps from
2.5H to 17.5H (3.5H steps from IH to 22H with the PS model).
1 0
o
TRACK/lI.SH
+
TRACK/ISH 1 0
1 1
1 1
+2 TRACK/l8.SH
+3 TRACK/22H
BVH-2000(U/C)/PS/PM
BVH-2180(U/C)/PS/PM