Sony SPP-A972 Service Manual page 40

U1019 U4082B
27 26 25 24 22
28 23
RX
ATTEN-
UATOR
BACKGROUND
LEVEL
NOISE
DETECTOR
DETECTOR
LEVEL COMPARATOR
DETECTOR
VCC
HYBRID
AMP 2
+
FILTER
AMP –
2
1 3 4 5
– BASE KEY Board –
U1 MC74HC595AF
16 15 14 13 12 11
VCC
20
21
DIAL
TONE
DETECTOR
BACKGROUND
NOISE
DETECTOR
COMPARATOR
AGC
TX
HYBRID
VR
VR
ATTENUATOR
AMP 1
+
–
9
6 7 8
10
SHIFT REGISTER
LATCH
GND
2 3 4 5 6 7
1
PARALLEL DATA
OUTPUT
19 17 15
18 16
VREF
LEVEL
DETECTOR
LEVEL
DETECTOR
MIC
VR
AMP
+
–
10 14
11 12 13
– HAND MAIN Board –
U1007 LP29811M5-3.0
VIN 1
GND 2
9
ON/OFF 3
8
– 51 –
OVER CURRENT/
OVER TEMP
PROTECTION
REFERENCE
REGULATOR
VOLTAGE
5 VOUT
4 N/C