Tuner Board - Philips MRD300/37 Service Manual

7-1

TUNER BOARD

TABLE OF CONTENTS
Internal IC Diagram ......................................................... 7-1
Circuit Diagram ................................................................ 7-2
PCB Layout Top View ...................................................... 7-3
PCB Layout Bottom View ................................................ 7-4
Parts List .......................................................................... 7-5
LA1837 EQUIVALENT SCHEMATIC
30 29 28 27 26 25 24
REG
AM AM
ALC AM
MIX RF.AMP
OSC
BUFF
AGC
AM IF DET
SD
COMP
AM
S-METER
FM AM/FM
S-CURVE
S-METER IF-BUFF
TUNING
DRIVE
FM
AM IF
DET
GND
1 2 3 4 5 6 7
LA72131 BLOCK DIAGRAM
REFERENCE
XIN
DIVIDER
XOUT
SWALLWOCOUNTER
FMIN 1/2
1/16 1/174bit8
12bit8 PROGRAMMOBLE
AMIN
DIVIDER
CE
DI CCB
DATASHIFTREGISTER LATCH
I/F
CL
DO
POWER
ON
V DD
RESET
V SS
B01 B02 B03
7-1
23 22 21 20 19 18 17 16
3 rd 5 th
DECODER
ANTI-BIRDIE
MUTE
P-DET
STEREO
SW
VCO FF FF FF PILOT
p
304kHz 38K 19k 19k q DET
2
STEREO
DRIVE
VCC
8 9 10 11 12 13 14 15
PHASE DETECTOR
CHARGE PUMP
UNLOCKDETECTOR
UNIVERSAL
COUNTER
B04 I01 I02
PD
AIN
AOUT
IFIN