JVC UX-A52 Service Manual page 41

LA1838 (IC1) : FM AM IF amp & Detector, FM MPX decoder
1. Block diagram
30 29 28
REG
AM
AM
ALC
MIX
OSC
BUFF
SD
COMP
FM
AM/FM
S-CLRVE
S-METER
IF-BUFF
PM
FM IF
DET
1 2
3
2. Pin function
Pin
Symbol I/O
No.
FM IN
I This is an input terminal of FM IF
1
signal.
AM MIX
2 O This is an out put terminal for AM
mixer.
3 FM IF I Bypass of FM IF
4 AM IF I Input of AM IF Signal.
GND
5 This is the device ground terminal.
6 TUNED
O When the set is tunning,this terminal
becomes "L".
STEREO O
7 Stereo indicator output. Stereo "L",
Mono: "H"
8
VCC This is the power supply terminal.
9 FM DET
FM detect transformer.
10 AM SD This is a terminal of AM ceramic filter.
FM VSM O
11 Adjust FM SD sensitivity.
12 AM VSM O Adjust AM SD sensitivity.
13 I/O
MUTE When the signal of IF REQ of IC121(
LC72131) appear, the signal of FM/AM
IF output. //Muting control input.
Change over the FM/AM input.
14
FM/AM I
"H" :FM, "L" : AM
MONO/ST O
15 Stereo : "H", Mono: "L"
27 26 25 24
FM
RF.AMP
AGC
DET
AM IF
AM
S-METER
TUNING STEREO
DRIVE DRIVE
GND
5
4 6 7
Function
23 22 21 20
DECODER
ANIT-BIRDIE
STEREO
P-DET
5N
SW
FF
VCO
38k
384KHz
VCC
8 9
10 11
Pin
I/O
Symbol
No.
16
L OUT O Left channel signal output.
17 R OUT O
Right channel signal output.
18
L IN I Input terminal of the Left channel post
AMP.
Input terminal of the Right channel
19 R IN I
post AMP.
20 O Mpx Right channel signal output.
RO
21 LO
O
Mpx Left channel signal output.
22 MPX IN I
Mpx input terminal
23 FM detection output.
FM OUT O
AM detection output.
24
AM DET O
I This is an AGC voltage input terminal
25 AM AGC
for AM
26 AFC This is an output terminal of voltage
for FM-AFC.
AM RF signal input.
27
AM RF I
28 REG O Register value between pin 26 and pin28
besides the frequency width of the
input signal.
AM OSC
29 This is a terminal of AM Local
oscillation circuit.
30 OSC BUFFER
AM Local oscillation Signal output.
O
UX-A52
19 18
17 16
MUTE
FF PILOT
FF
/
19k 19k DET
2 LS
/
12 13 14 15
Function
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