Pioneer YPM-2106ZF, Service Manual

Page: 36 / 43

36
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.
TE
AMP
DIG.
EQ
86
F
E
TD
TOM
TOP
IC301
BA5985FM
LENS
IC201 UPD63711GC
87
63 25
22
17
18
JUMP
PARAMETERS
DAC CONTROL
A/D
R303
10k
R302
15k
t1
t2
GAIN NORMAL
TD
KICK
BRAKE
TEC
T. BRAKE
EQUALIZER
T. SERVO
CLOSED
OPEN
NORMAL
GAIN UP
OFF
ON
t1
TD
TEC
(10 TRACK)
EQUALIZER
T. BRAKE
SERVO
SD
2.9mS (4.10 TRACK JUMP)
5.8mS (32 TRACK JUMP)
GAIN UP
NORMAL
ON
OFF
OPEN
CLOSED
t2
50mS
t
Fig.12 : TRACKING SERVO BLOCK DIAGRAM
Fig.13 : SINGLE TRACK JUMP
Fig.14 : MULTI-TRACK JUMP