Read Sharp DV-560H (serv.man2) Service Manual online
DV-560H
8-1
8. OPERATION OF PICKUP
8-1. CIRCUIT CONFIGURATION OF PICKUP
The pickup unit reads signals from the disk, and the flexible cable is connected to the board. The following signals flow
through the cable.
8-2. EQUIVALENT CIRCUIT OF PICKUP
Focus
When electric current is flowed from FO+ to FO-, the lens comes to near the disk.
FO+, FO-
Tracking
When electric current is flowed from TR+ to TR-, the lens goes toward the outer
TR+, TR-
circumference.
Gain switching
DVD one Layer
Low gain
Sga : GND
Sga
DVD two Layer
High gain Sga : +5V
CD
8-3. POLARITIES OF SIGNAL
8-4. SIGNALS OF PICKUP
8-4-1. Tracking drive signal (TR+, TR-)
The signal drives the tracking servo mechanism which projects the beam on the track by moving the objective lens (OL)
to the outer or inner circumference (at a right angle against the track) of the disk.
Since an eccentricity error of 25
µ
mP-P is generated due to the eccentricity of 100
µ
mP-P of the DVD disk when the disk
is fixed, the error is reduced to
±
0.22
µ
m or less with the tracking servo.
FO+
TR–
TR+
FO–
ACTUATOR
OSC
V
OS
LD
PD
VA
VB
VC
VD
Sga
V
raf
V
cc
GND
–
+
–
+
–
+
–
+
+
–
+
–
+
–
+
HOLOGRAM LASER UNIT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1
TR–
FO+
TR+
FO–
VR
PD
V
CC
GND
LD
GND
V
OS
NC
NC
V
ref
(VCC/2)
VA
VC
Sga
GND
VB
VD
(NC)
Power adjust
HIGH-FREQUENCY CONVOLUTION
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