8
3.1.1.2 Operating principle of servo circuit:
：
Servo circuit is mainly composed of pick up interface, servo drive, system control and signal
processing circuits and servo software (built in NAND FLASH) and other modules.
Servo drive circuit: servo drive circuit has one drive group. This group is composed of
U
2(
TPIC
2050)
and peripheral circuit which are used to drive spindle motor, focus coil, tracking coi and
feed motor. TPIC
2050
has
servo
control
circuit
and
drive
circuit
built
in
.
ommon
C
servo circuit troubles:
1.
Fail
to
open
/
close
tray door.
2.
Fail
to load discs for loader driver error.
3.
Keep
displaying “loading”, “No disc” or “Unkown disc”.
4.
Fail
to
view
servo
software version in setup menu, loader malfunction.
5.
Fail
to
load
disc
for
poor contact of flat cable that connects the loader.
A B C D E F G H DVDRFO BDRFO
T
P
IC
20
50
M
t8
58
0
752BD player adopts SONY 480 loader and MT8580 decoding scheme. And its servo circuit is
mainly composed of decoding chip Mt8580, driver IC tpic2050 and other components.
Please refer to Figure 3.1.1.1 below:
.
S
E
R
V
O D
R
I
V
E
R
TR+
TR-
FR+
FR-
TIL+
TIL-
U
V
W
COMMON
NAND
FLASH
LOAD+
LOAD-
SA_CO_B-
SA_CO_A-
SLED_B-
SLED_A-
DRIVER_CS_IN
DRIVER_SCLK_IN
DRIVER_DATA_IN
DRIVER_DATA_OUT
XRESER_IN
3.1.1 Servo circuit
3.1.1.1 Servo circuit overview:
Figure 3.1.1.1 Block diagram of servo circuit
BD pick up
component
Spindle
motor
Feed
motor
D
ec
od
in
g a
nd s
er
vo p
ro
ce
ss
in
g c
ir
cu
it
Tray open/close motor
-6-
