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5
6) RF level automatic adjustment (RFAGC)
This adjustment is performed in order to adjust variation
of RF signal (RFO) level to fixed value and to realize
reliable signal transmission. The adjustment is performed
with changing amp gain between RFI and RFO.
Adjustment steps
(1) The microcomputer reads out output from RF level
detect circuit inside servo LSI by a command.
(2) The microcomputer calculates desired RFO level of
amp gain volume from read value.
(3) The microcomputer sends an appropriate command
to servo LSI to reach to the gain volume of (2).
This adjustment is performed at the following timing,
• During set-up, only focus-close is finished
• At the point of set-up completion (just before playing)
• During playing, after recovering from out-of-focus
Entire RFAMP GAIN
+ 12dB
+ 6dB
TYP
+6dB play increases because of dirt of
lens, etc. (Set-up starts with TYP gain.)
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6
7) Adjustment of gain of preamp stage
If there is lens dirt, or reflected light of a disc is notably
small during CD-RW replaying, gain of entire RFAMP(FE,
TE, RF amp) should be +6dB, +12dB according to the
situation.
Adjustment steps
When reflected light of a disc is notably small during set-
up, the entire RFAMP should be +6dB, +12dB. In
addition, when changing gain, perform again the set-up
procedure from the start. When it is considered that "the
entire gain of RFAMP is always played at +6dB", perform
the set-up at +6dB in advance from the next time.
See the figure below.
Playing with +12dB gain with CD-RW, etc.
Fig.14 Conceptual diagram of gain of preamp stage
CX-3168
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7
Detecting that "lens is dirty"
and playing with +6dB from
the start
7
8
A
B
C
D
Time
E
F
13
8
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