JVC UX-H35 Service Manual page 30

UX-H35
4.7 LA1838 (IC1): FM AM IF amp & Detector, FM MPX decoder
• Block Diagram
29
30
AM
ALC
OSC
BUFF
FM
S-CLRVE
S-METER
FM IF
1 2
• Pin Function
Pin No. Symbol
1 FM IN
2 AM MIX
3 FM IF
4 AM IF
5 GND
6
TUNED
7
STEREO
8 VCC
9 FM DET
10 AM SD
11 FM VSM
12 AM VSM
13 MUTE
14
FM/AM
15
MONO/ST
16 L OUT
17 R OUT
18 L IN
19 R IN
20 RO
21 LO
22 MPX IN
23 FM OUT
24 AM DET
25 AM AGC
26 AFC
27 AM RF
28 REG
29 AM OSC
30 OSC BUFFER
1-30 (No.22031)
27
28 26 25
REG
AM
FM
MIX
RF.AMP
AGC
DET
AM IF
SD
COMP
AM
S-METER
AM/FM
IF-BUFF
TUNING
DRIVE
PM
DET
GND
5
3 4 6
I/O
I This is an input terminal of FM IF signal.
O This is an out put terminal for AM mixer.
I Bypass of FM IF
I Input of AM IF Signal.
- This is the device ground terminal.
O When the set is tunning, this terminal becomes "L".
O Stereo indicator output. Stereo "L", Mono: "H"
- This is the power supply terminal.
- FM detect transformer.
- This is a terminal of AM ceramic filter.
O Adjust FM SD sensitivity.
O Adjust AM SD sensitivity.
I/O When the signal of IF REQ of IC121(LC72131) appear, the signal of FM/AM IF output. //Muting
control input.
I Change over the FM/AM input. "H" :FM, "L" : AM
O Stereo : "H", Mono: "L"
O Left channel signal output.
O Right channel signal output.
I Input terminal of the Left channel post AMP.
I Input terminal of the Right channel post AMP.
O Mpx Right channel signal output.
O Mpx Left channel signal output.
I Mpx input terminal
O FM detection output.
O AM detection output.
I This is an AGC voltage input terminal for AM
- This is an output terminal of voltage for FM-AFC.
I AM RF signal input.
O Register value between pin 26 and pin28 besides the frequency width of the input signal.
- This is a terminal of AM Local oscillation circuit.
O AM Local oscillation Signal output.
24 23 22 21
DECODER
ANIT-BIRDIE
STEREO
P-DET
VCO
384KHz
STEREO
DRIVE
VCC
8 9 10
7
Function
18
20 19 17
MUTE
5N
SW
FF FF PILOT
FF
38k /
19k 19k LS DET
2 /
12 13
11 14
16
15