Pioneer YPM-2306ZFWL Panduan Servis - Halaman 36

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Pioneer YPM-2306ZFWL Panduan Servis
YPM-2306ZF
2) Tracking Servo System
The digital equalizer is employed for the main equalizer
on the tracking servo. Fig.12 shows the tracking servo
block diagram.
a) Track jump
When the LSI receives the track jump command from
the microcomputer, the operation is carried out auto-
matically by the auto sequence function of the LSI. This
system has five types of track jumps used for the
search : 1, 4, 10, 32 and 32 × 3. In the test mode, in addi-
tion to three jumps (1, 32 and 32 × 3), move of the car-
riage can be check by mode selection. For track jumps,
the microcomputer sets almost half of tracks (5 tracks
for 10 tracks, for instance) and counts the set number of
tracks using the TEC signals. When the microcomputer
has counted the set number of tracks, it outputs the
brake pulse for a fixed period of time (duration can be
specified with the command) to stop the lens. In this
way, the tracking is closed and normal play is contin-
ued.
To improve the servo loop retracting performance just
after the track jump, the brake circuit is turned on for 50
ms after the brake pulse has been terminated to
increase gain of the tracking servo.
Fast forward and reverse operations are realized by
through consecutive signal track jumps. The speed is
about 10 times as fast as that in the normal mode.
36
IC201 UPD63711GC
F
86
TE
DIG.
A/D
E
AMP
EQ
87
CONTROL
JUMP
PARAMETERS
Fig.12 : TRACKING SERVO BLOCK DIAGRAM
TD
TEC
T. BRAKE
EQUALIZER
T. SERVO
Fig.13 : SINGLE TRACK JUMP
TD
TEC
(10 TRACK)
EQUALIZER
T. BRAKE
SERVO
SD
Fig.14 : MULTI-TRACK JUMP
IC301
BA5985FM
R303
10k
22
R302
TD
17
15k
DAC
63
25
18
BRAKE
t2
t1
KICK
GAIN NORMAL
t1
t2
50mS
t
2.9mS (4.10 TRACK JUMP)
5.8mS (32 TRACK JUMP)
TOM
LENS
TOP
ON
OFF
GAIN UP
NORMAL
OPEN
CLOSED
GAIN UP
NORMAL
ON
OFF
OPEN
CLOSED