Philips 28PW9618, Руководство по обслуживанию

Страница: 140 / 172

Circuit Descriptions, Abbreviation List, and IC Data Sheets
EN 140 EM6E 9.
The system uses normal FM modulation/demodulation and
also uses the Zenith stereo system. However, the frequencies
used are different in this respect: the sub carrier frequency= 3
* 15.625 kHz = 46.875 kHz (chosen because interference zero-
beats with the TV line freq). Consequently, the pilot frequency
is 23.4375 kHz (half of sub carrier).
The transmitter amplifier has an output power of 10 mW and
drives it into an internal printed antenna (the 433 MHz version
of an external antenna).
Transmitter
Block Diagram
Figure 9-11 Block diagram transmitter
Audio Compander
The audio compressor uses a SA572 (7112), which is intended
for high-end applications. It is used together with a low noise
OpAmp (7113). There is no audio input filtering ahead of the
compressor. Therefore, it can only be used when the source is
having no frequency components above 20 kHz, otherwise the
compander's linearity will be at risk. This is realised with a
digital filter on the SSP.
Graphically the operation of a "compressing and expanding"
(=companding) system can be understood from following
figure:
Figure 9-12 Compressing/Expanding graphics
Figure 9-13 Companding circuit
Basically, the circuit comes down to following simple circuit:
Figure 9-14 Basic compander configuration
CL36532008_069.eps
220403
TRANSMITTER R
B14B
1101
1 2
7113
NJM4565M
7112
SA572D
3
∆
G
1
7
6
5
5
11
RECTI-
FIER
R
L
L
R
2
3
3 2
5
6
TO TV
CONNECTION
TO1103
7
8
+8V
+5V
PD
7119
6105, 7118
4
I2C-CLOCK
POWER DOWN
DETECTOR
I2C-DATA
7117
LD1117DT
11V_S
F124
F140
F141
F145
F144
F131
F149
F147
F113
F110
F114
F130
F126
7
7110
74HC4060
OSCILLATOR
ENABLE
(Low)
256
512
PRE-EMPHASIS
- COMPANDER - - STEREO ENCODER -
- PLL -
MULTIPLEXED
2165, 3160, 3190
2166, 3161, 3191
PRE-EMPHASIS
9
3
13
12
VPIL
3
5
6 2
1
16
5
14
7
9
8
2
SDA
I2C-D
A
T
A
I2C-CLOCK
SCL
VERSION
SELECTION
433MHz
or
864MHz
6
11
ADC
1105
4MHz
VPIL
VFIL
(ENABLE)
+6V
3105
3106
3179 6102
BB151
(VARICAP)
7102
OSC
VOSC
(ENABLE)
X2 (ENABLE)
7103
BFR92A
7104
7105
5112
+8b
7101
TSA5060A
MPX
MODULATION
LEVEL ADJ.
3
5
7111
74HC4053HD
7116-B
NJM4565M
7116-A
4
7
3174
3177
V
9
SUBC
46,875kHz
6
LIMITER LOW-PASS
LOCAL
OSCILLATOR
FREQUENCY
MULTIPLIER
FILTER
OUTPUT
7106
BFG520
SYNTHESIZER
14
13 PILOT 23,4375kHz
PD
10
11
1106
12MHz
V
V
V
X2
COMPRESSION
IN
EXPANDOR
OUT
REL LEVEL ABS LEVEL
dB dBM
3.0V
547.6MV
400MV
100MV
10MV
1MV
+29.54
+14.77
+12.0
0.0
–20
–40
–60
–80
+11.76
–3.00
–5.78
–17.78
–37.78
–57.78
–77.78
–97.78
VRMS
100
µ
V
10
µ
V
INPUT TO
∆
G
AND RECT
2
1
2
CL36532008_073.eps
130503
BUFFER
G
RECT
COMPANDER
10K
3159
1u
2143
NJM4565M
7113-A
3
2
1
8
4
3K3
3156
F140
100K 3142
4n7
2145
2141 470p
18K
3151
22n
2160
18K
3152
47K
3147
F143
18K
3150
2164
2u2 50V
GIB
8
GND
5 GOA
11 GOB
2 RCA
14 RCB
3 RIA
13 RIB
6 THTA
10 THTB
1 TRTA
15 TRTB
16
VCC
SA572D
7112
4 ACA
12 ACB
7 GIA
9
47K
3146
3145
15K
16V
47u
2139
2161
2u2 50V
2157
2u2
50V
2147
1u 10K
3158
22n
2159
16V
10u
2153
F144
F145
22p
2151
5
6
7
8
4 7113-B
NJM4565M
100K
3143
15K
3144
2154
10u
16V
22p
2152
82K
3148
1K0
3140
22n
2140
470p 2142
1K0
3154
3141
1K0
1u
2148
F141
16V 10u
2149
18K
3153
4n7
2146
2150
10u 16V
1K0
3155
2K2
3168
3167
2K2
F142
270p 2156
3157
3K3
50V 2u2
2162
1u
2144
470p
2176
82K
270p
2155
3149
2u2
2158
50V
50V 2u2
2163
L
R
+8V
+8V
+8V
CL36532008_074.eps
130503
CL36532008_075.eps
060503
X1
1k
R1
C1
2.2u
IN
Vref
+8V
1k
R3
C5
2.2u
1k
R2 C2
2.2u
C4
10u
C3
1u
OUT
Gain cell
Rectifier