
3.2.5 Disc in/out circuit
1. Disc in/out circuit is shown as the following figure 3.2.5.1:
Figure 3.2.5.1 Disc in/out circuit diagram
R325
100R
R327
100R
Q309
8050D
Q308
8050D
Q306
8550D
Q307
8550D
R323
220R
R324
220R
R328
10K
R326
2.2R\1/4W
TC308
47uF/16V
TC309
47uF/16V
LOAD+
LOAD-
MO_VCC
TRCLOSE
Q310
9014-S
TROPEN
TROPEN
MT1389
2. Working principle: INDISC, OUTDISI are disc in/out control signals and are connected to pin 39,
54 of U201 (MT1389) respectively. LOAD+, LOAD- connect with two ends of electric machine to control.
When users are performing disc out operation, servo control chip U201 (MT1389) sends out control
signal through pin 39, 54 and changes level of LOAD+, LOAD- to change the rotation direction of electric
machine to realize disc in/out function. The working process of disc in/out circuit is shown as follows:
OUT disc : VCC
Q306CE electrode on
LOAD+
Electric machine
LOAD-
Q309CE electrode
on
R326
Ground
When not opening disc tray, pin 39 and 54 of U201 (MT1389) are low level. When opening disc tray,
pin39 of U201 (MT1389) sends a high level; Q309 is on; Q309 collector electrode changes into low
level; LOAD- changes into low level; Q306 base electrode changes into low level; Q306 is on. Q306
collector electrode changes into high level and LOAD+ changes into high level.
IN disc: VCC
Q307CE electrode on
LOAD-
Electric machine
LOAD+
Q308CE electrode
on
R326
Ground
When closing disc tray, pin 54 of U201 (MT1389) sends a high level; Q308 is on; collector electrode
changes into low level; LOAD+ is low level; base electrode through R230 and Q307 is low level; Q307 is
on; Q307 collector electrode changes into high level; LOAD- changes into high level.
The function of Q310 is interlock IN DISC and OUT DISC signal to ensure the two are not high level
at the same time. When the two are high level input, base electrode of Q309 is made to low level through
Q310 on to ensure the normal working of disc in/out circuit. The function of electrolytic capacitor TC308
and TC307 is to avoid the sudden change of the voltage on two ends of disc in/out electric machine to
make disc in/out acts smooth.
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Содержание DV725SI
Страница 1: ...service manual DV725SI...
Страница 62: ...21 27M clock signal waveform diagram 22 Reset circuit waveform diagram URST Dv33 58...
Страница 95: ...5 1 7 Surface layer of DECODE SERVO Board 91...
Страница 96: ...5 1 8 Bottom layer of DECODE SERVO Board 92...