Pioneer YPM-MG2196ZF Service Manual page 59

2) Tracking servo system
The main equalizer of tracking servo is located in the
UPD63702AGF. Fig. 11 shows block diagram of the
tracking servo.
a) Track jump
Track jump is automatically performed by the auto
sequence function in LSI when the LSI accepts com-
mand. The system has six types of jump (1, 4, 10, 32,
32x2, and 32x3) for track jump during searching. In Test
mode, the system can select and check these jump
types and CRG move by selecting a mode. The micro-
computer sets half of the total number of track jumps
(two tracks if the total number of tracks are four), and
counts the set number of tracks by using TEC signal.
The system outputs brake pulse for a specified time (set
by the microcomputer) from the point of time when the
set number is counted, and stops the lens. Thus, track-
ing is closed, and the system can continue normal play-
back.
To improve servo withdrawal during track jump, the
system sets the brake circuit to ON for 60 ms after
brake pulse so that gain of the tracking servo can be
increased.
FF/REV in normal mode is made by continuously per-
forming single jump approximately ten times faster
than in normal playback.
IC 201 UPD63702AGF
TRACKING
ERROR
DIGITAL
77
A/D
EQUALIZER
CONTROL
JUMP
PARAMETERS
Fig. 11 Tracking servo block diagram
TIN
t1
KICK
TEC
T. BRAKE
EQUALIZER
GAIN NORMAL
T. SERVO
Fig. 12 Single track jump
t1
TIN
TEC
(10 TRACK)
EQUALIZER
T. BRAKE
SERVO
CIN
Fig. 13 Multi track jump
YPM-MG2196ZF
IC301
BA5986FM
TD
11
DAC 63 5
R303
12
6
10kΩ
D/A
TIN
TOM
7
R304
27kΩ
DRIVER
BRAKE
t2
ON
OFF
GAIN UP
NORMAL
OPEN
CLOSED
t2
GAIN UP
60mS
NORMAL
ON
OFF
OPEN
CLOSED
t
2.8mS (4.10 TRACK JUMP)
5.8mS (32 TRACK JUMP)
TOP
LENS
59