Sharp MD-R3H Service Manual page 16

MD-R3H
Reference
CD level
1/2 VCC
Figure 16-1 TRACKING ERROR BALANCE
Apply a black tape
(1.2 to 1.5 wide).
It is allowed use any disc in addition
to test disc.
Do not apply the black tape to the
initialization part (TOC).
Figure 16-2 FOCUS OFFSET/TRACKING OFFSET
Do not plug in or unplug the optical pickup
connection cable while power is on.
Otherwise damage may occur.
For your safety do not attempt to adjust
the half-fixed resistor for laser power
adjustment.
OPTICAL PICKUP PWB
Vertically
symmetrical
waveform
0.5~1.5Vp - p
TP751
1 FG1
2 FG2
3 HF
4 TG1
5 FG2
6 1/2Vcc
TRACKING
OFFSET
Figure 16-6 ADJUSTMENT POINTS
– 16 –
Adjust to get uniform and minimized
error waveform.
Figure 16-3 FOCUS OFFSET/TRACKING OFFSET
FG1
27kΩ
TP751, pin 1
TG1
TP751, pin 4
Figure 16-4 LOW-PASS FILTER
TP751,
pin 4 0.0082
(TG1)
100K
100K
TP751,
pin 6
(1/2Vcc)
100K
100K
TP751,
pin 2
0.0082
(TG2)
Figure 16-5 TRACKING GAIN RELAY CIRCUIT
CD SERVO PWB
CNP700A
CNS903
VR754
VR753
1 6
TP751
TRACKING
FOCUS
GAIN
OFFSET
Waveform
observation
point
820P
1/2 VCC
2.2K
CH - 1
820P
VV
VV
820P
CH - 2
2.2K
VR751
VR752
TRACKING
ERROR BALANCE
Signal
transmitter