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UX-L40R/UX-L30R
Description of major ICs
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
Input of AM IF signal.
I
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.
O
FM VSM
Adjust FM SD sensitivity.
11
AM VSM
12
O
Adjust AM SD sensitivity.
13
MUTE
I/O
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
Stereo : "H", Mono: "L"
15
1-30
27
26
25
24
FM
RF.AMP
AGC
DET
AM IF
AM
S-METER
TUNING
STEREO
DRIVE
DRIVE
GND
5
4
6
7
Function
22
21
20
23
DECODER
ANIT-BIRDIE
STEREO
P-DET
5N
SW
FF
VCO
38k
384KHz
VCC
8
9
10
11
Pin
I/O
Symbol
No.
16
O
L OUT
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.
O
Mpx Right channel signal output.
20
RO
21
LO
O
Mpx Left channel signal output.
22
MPX IN
I
Mpx input terminal
23
O
FM detection output.
FM OUT
AM detection output.
24
AM DET
O
This is an AGC voltage input terminal
25
AM AGC
I
for AM
This is an output terminal of voltage
26
AFC
for FM-AFC.
AM RF signal input.
27
I
AM RF
28
REG
O
Register value between pin 26 and pin28
besides the frequency width of the
input signal.
29
AM OSC
This is a terminal of AM local
oscillation circuit.
30 OSC BUFFER
AM Local oscillation signal output.
O
19
18
17
16
MUTE
FF
PILOT
FF
/
19k
19k
LS
DET
2
/
12
13
14
15
Function
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