BBK DV725SI, Руководство по обслуживанию

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Note: 1. When reading DVD, there are only A, B, C, D signals.
2. When reading CD, there are A, B, C, D, E, F signals.
3. RFO=A+B+C+D.
4. Focus error signal=(A+C)-(B+D) Trace error signal=E-F.
Servo system of this player adopts SANYO MTK decode solution (FLASH (16M)
+ SDRAM (64M)), and its servo circuit is mainly composed of front end signal processing, digital servo
processing, digital signal processing IC MT1389E and drive circuit D5954, in which MT1389E is also the
main composed part of decode circuit. Servo circuit block diagram is shown as in the following figure
3.2.2 Servo circuit
3.2.2.1:
FOSO
FMSO
TRSO
DMSO
A B C D E F RFO
IOA
LDO2
LDO2
MD11
Switch circuit
APC circuit
Main axis control
detect circuit
Main axis electric machine
Feed electric machine
Xs101
D5954
MT1389
Disc in/out
circuit
TK-
TK+
FC+
FC-
SL+
SL-
SP-
SP+
1
23
6
26
15
16
14
13
17
18
12
11
Figure 3.2.2.1 Servo circuit block diagram
2. Working principle
After power on, machine displays OPEN, after loading disc, loader lens begins to reset, when laser
head is in the position, detect switch will give a signal to MT1389, MT1389 begins to output focus, main
axis and light emission signals, disc begins to rotate, laser head begins to identify disc information, and
judge whether disc is CD or DVD according to disc information to facilitate level from IOA pin and control
disc switch circuit and laser head PD IC to make the corresponding control acts. At the same time,
MT1389 control laser output power through laser power control circuit.
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