Samsung MM-18 Service Manual page 17

mm18(10) 3/23/98 3:14 PM
Special Circuit Descriptions
5-1-3 Tracking Error Amp
The current signals from the side spot photo diode (E and F) are input to the E and F pin and converted into
voltage signals by E I-V and F I-V AMP. The output of tracking error amp is due to the difference between
E I-V AMP voltage output.
The E-F balance can be adjusted by modifying the gain of E I-V AMP, and the tracking gain(Pin TE1) can be
adjusted automatically by micom program.
5-1-4 Focus OK Circuit
Extracting the DC part of RFI and RFO and comparing with the basic DC level, if RF Level is more than basic
level, the FOK is output. The focus OK circuit generates a timing window of focus on to monitor the focus
search status of focus serve.
5-2
Page 5-2
67 IV AMP
F
68 IV AMP
E
TGFI GAIN - UP/DOWN
EI 79
BAL< 4 0 >
GAIN< 3 : 0 >
from Digital
40K
74
75
40K
LPFT
TE1
54 55
-
-
+
40K
-
57K
-
+
+
90K
VC+0.625V
BALL
WIN COMP
BALH
To ISTAT,TRCNT
TGL
WIN COMP
TGH
40 FOK
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