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GB 66
8.
8.3.7
HF Path
Description
The pre-amplified HF-signal is presented to both n=1 and
n=2 amplifier circuits. The mux/demux switches via software
and micro processor controlled S1 and S2 lines between
either one of the amplified n=1 or n=2 signals. The signal will
n-dependant filtering
n=1 AMP
3173
3174
430R
430R
2
n=2 AMP
PRE AMP
HF
3191
3192
430R
430R
2164
180p
DC Settings
Set the power and reset connections as described above in
"1.1.1. Supply Voltages". Check the following voltages :
Force
Pin
Emitter
S1 and S2 "HIGH"
Collector
S1 and S2 "LOW"
Collector
S1 and S2 "HIGH"
13
S1 and S2 "LOW"
13
S1 and S2 "HIGH"
3
S1 and S2 "LOW"
3
Figure 8-27
CDR779
Faultfinding Guide
+5VHF
HFGND
HFGND
7023
BFS20
HFGND
2143
390p
330p
2149
680p
HFGND
+5VHF
HF
7009
BFS20
HFGND
HF
HFGND
HFGND
Location
Measure
2.4 ± 10%
7006
1.9 ± 10%
7010
1.9 ± 10%
7010
1.6 ± 10%
7025
1.6 ± 10%
7025
3.2 ± 10%
7025
3.2 ± 10%
7025
CL96532086_058.eps
then follow another amplification and filtering circuit. The
filtering again is controlled by the S1 and S2 lines, dependant
on whether the disc starts up (speed n=1, S1 and S2 Low),
disc plays at speed n=1 (S1 Low, S2 High) or disc plays at
speed n=2 (S1 and S2 High).
DUAL 4 CHANNEL
MUX/DEMUX
+5VHF
7025
74HCT4052D
2130
10
16
VCC
0
0
100n
4x
9
7
3
VEE
1
6
8
GND
G4
HFGND
1
0
5
HFGND
1
3
2
HFGND
2
HF
4
3
2141
12
2n2
14
13
2146
15
1n5
11
9
+5VHF
HF
HFGND
1K
3196
BC858B
7007
7010
BC848B
HFGND
HFGND
Figure 8-26
080999
3
S1
S2
HFGND
7000
SAA7324
HFIN
2142
F309
1
2145
22n
F156
3178
HFGND
F310
2
47p
1K
3181
2150
3
22K
47n
F159
HFGND
4
5
CL96532086_057.eps
HFREF
HFIN
ISLICE
FRONT
VSSA1
END
VDDA1
080999
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