2. Working principle
After loading disc in the player, IOA port of MT1389 is defaulted high level to make Q107 saturation
on and form loop together with CD laser power control circuit on CD. At the same time, IOA also goes to
loader PD IC to switch, disc begins to rotate, when servo management system recognizes that the disc
in player is not CD disc, IQA pin outputs low level to make Q107 cut off and make Q108 on, and form
loop together with DVD laser power control circuit on loader to perform disc reading acts. After disc tray
door opens, IOA keeps the state before opening disc tray door. If the player cannot recognize which disc
it is, IQA pin will switch continuously until reading disc or system judges that there is no disc.
Note: Q108 and Q109 are MOS tube
3. Key point voltage (unit: V) is shown as the following table:
- 84 -
Vcc
GND
GND
Vcc
DISC
TROUT
DESCEJT
PICK_UP
3.2.5 Disc slot-in circuit
LD1506S adopts dual slot-in and sealed-style all-steel with compact structure. There is a all-steel
disc pressing system, in which disc is tightly pressed through 3 small steel plates, thus it is applicable
tothose discs with problem. It is really full-compatible with reading 12cm large disk and also 8cm small
disk. The player adopts light induction style to read disk. As long as you place the disc on the door, the
loader will absorb it in automatically.
1. Disc slot-in circuit is shown in the figure 3.2.5.1:
Q1
Q2
Figure 3.2.5.1 Disc slot-in circuit diagram
Base
electrode B
Collector C
Emitter E
Grid
electrode G
Drain
electrode D
Source
electrode S
G
D
S
IOA
DVD disc
0
3.86
0
3.81
0.18
0
0
0
0
0
VCD disc
0.64
0.1
0
0
0
0
3.27
0.18
0
3.3
State
Q107
Q108
Q109