Samsung Electronics
5-1
5. Special Circuit Descriptions
5-1 RF Amp Block
5-1-1 RF Amplifier
5-1-2 Focus Error Amp
PD1
PD2
VC
RF-
RFO
RF SUMMINGAMP
VC
VC
VB
10K
58K
IV AMP
VA
10K
58K
IV AMP
+
-
+
-
+
-
65
66
73
74
32K
160K
4K
32K
164K
3K
+
-
+
-
+
-
63
59
FE1
VB>
VA>
SW1
FEBIAS
FEBIAS
sev-stopb
VC
fe-stopb
fcmpo
sev-stop
X1
X2
X4
X8
X16
<5 Bit Counter>
The two currents from input pins PD1 (A+C) and PD2 (B+D) are converted into voltages through I/V Amp,
and they are added to RF summing Amp. The photo diode (A+B+C+D) signal which is I-V changed is
outputted by RFO (pin74). At this pin, the eye pattern can be checked.
The output of the focus error amp is the difference between RF I-V AMP(1) output Va and RF I-V AMP(2)
output Vb,just is the Photo Diode ((A+C) - (B+D)) signal which is I-V changed.
The focus error bias voltage applied to the (+) of focus error amp can be changed by D/A converter as shown
in diagram, so that the offset of focus error amp can be adjust automatical.
Focus error bias can be adjusted from the range of +100mV ~ -100mV by connectiong the resistor with pin 63
(FEBIAS).
Summary of Contents for MM-28
Page 2: ...ELECTRONICS Samsung Electronics Co Ltd March 1998 Printed in Korea Code no AH68 20188A ...
Page 8: ...TIMER ON OFF TIMER CLOCK Remote Control ...
Page 45: ...Samsung Electronics 9 5 Block Diagrams BA4560 LIC1 MIC1 OPTION ...
Page 56: ...10 PCB Diagrams 10 1 Main Samsung Electronics 10 1 ...
Page 57: ...10 2 Front PCB Diagrams 10 2 Samsung Electronics ...
Page 58: ...10 3 CD PCB Diagrams 10 3 1 Main Samsung Electronics 10 3 ...
Page 59: ...11 Wiring Diagram Samsung Electronics 11 1 ...
Page 61: ...UIC1 LC866232A 12 2 Samsung Electronics Schematic Diagrams 12 2 Front ...