Sony ICF-C795RC Service Manual ▷ View online
ICF-C795RC
– 9 –
– 10 –
– 11 –
4-1.
BLOCK DIAGRAM
SECTION 4
DIAGRAMS
12
9
14
17
10
5
7
FM
FRONT-END
AGC
AMPLIFIER
ANTENNA
RECTIFIER &
INTEGRATOR
DECODER
FM
IF AMP
AF
POWER AMP
AM IF AMP,
AGC, DET
AM
FRONT-END
16
19
FM RF
IN
IN
FM/AM
FE OUT
CF2
10.7MHz
CF1
450kHz
CF3
10.7MHz
FM
RF
RF
FM
IF IN
IF IN
2
FM
DISCRIMINATOR
TUNING METER
FM
DISCRI
DISCRI
27
AF
OUT
SP301
(SPEAKER)
AF
IN
IN
23
24
DET
OUT
AM
IF IN
IF IN
METER
NF
VOL
15
1
2
3
4
FM/AM
BAND
SELECT
AM OSC
L5
AM OSC
L4
FM OSC
X50
75kHz
X451
77.5kHz
L1
AM FERRITE-ROD
ANTENNA
L451
FERRITE-ROD
ANTENNA
L451
ANT1
FM LEAD
ANTENNA
FM OSC
AM RF
IN
IN
L3
FM RF
FM/AM FRONT-END,
FM/AM IF AMP, DET, AGC, AF AMP
IC1
FM/AM PLL
IC50
TIME CODE RECEIVER
IC451
SYSTEM CONTROLLER,
LCD DRIVER, KEY CONTROL
IC100
TC1
D4-1
B+
TC3
VR1
VOL
+
+
L4
FM VCO VOLTAGE
D74
A RADIO
D75
B BUZZER
S50
BRIGHTNESS
(LCD BACK LIGHT)
D70 – 73
(LCD BACK LIGHT)
D74
D75
–2
–1
L5
AM VCO VOLTAGE
L1, TC1
AM TRACKING
L3, TC3
FM TRACKING
T1
AM IF
B.P.F.
BPF1
LOW-PASS FILTER
Q50, 51
LED DRIVE
Q53, 54
MUTING
Q4
• SIGNAL PATH
: FM
: AM
05
D2
D3
AC IN
BACKUP B+
(SYSTEM CONTROLLER IC100 B+)
B+
BZ-CTRL
35
ALM A
6
ALM B
7
BUZZER
36
DATA
DATA IN
DA
PD1
27
5
15
CLK
CK
26
4
CE
CE
34
3
MUTE
PDET
33
28
RESET
18
AM IN
11
FM IN
XOUT
XIN
22
23
X101
4.19MHz
X1
X2
19
20
X100
32.768kHz
XT1
1
BIAS
2
VLC0
3
VLC1
4
VLC2
XT2
S0 – S23
12
P1
8
D100
D101
VT B+
RECT
D351 – 354
REGULATOR
Q57
T301
POWER
TRANSFORMER
RECT
D355
D355
RESET SIGNAL
GENERATOR
IC101
COM0 – COM3
S101, 201 – 218
(KEY MATRIX)
60 – 37
61 – 64
KS0 – KS4
10 – 13, 8
KR0 – KR3
14 – 17
LIQUID CRYSTAL DISPLAY
LCD100
LCD REFERENCE
VOLTAGE GENERATOR
IC102
D4-2
D102
D60, 61
HIGH
LOW
REC
DEC
INT
RF
IN
IN
Q2A
Q2B
Q1A
Q1B
25
13
14
FLA
FLB
10
11
5
6
7
TCO
16
9
8
2
MAIN KEY board
MAIN board
TRANSFORMER board
ANTENNA board
ALARM KEY board
• Circuit Boards Location
ICF-C795RC
– 12 –
– 13 –
– 14 –
4-2.
SCHEMATIC DIAGRAM
•
See page 17 for IC Block Diagrams.
• Waveforms
– MAIN board –
– MAIN board –
1
IC50
2
(XIN)
500 mV/DIV, 5 µs/DIV
3
IC100
ws
(X1) (
*
1)
1 V/DIV, 100 ns/DIV
2
IC100
ql
(XT1)
1 V/DIV, 10 µs/DIV
*
1)
Oscillation will be given out for 250 ms with following conditions.
• Turn the radio on.
• Change the band.
• Change the tuning (manual or preset).
• Turn the radio on.
• Change the band.
• Change the tuning (manual or preset).
1.8 Vp-p
13.3
µ
s
2 Vp-p
30.5
µ
s
240 ns
2.7 Vp-p
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. pF: µµF
• All capacitors are in µF unless otherwise noted. pF: µµF
50 WV or less are not indicated except for electrolytics
and tantalums.
and tantalums.
• All resistors are in
Ω
and
1
/
4
W or less unless otherwise
specified.
•
f
: internal component.
•
C
: panel designation.
•
U
: B+ Line.
•
H
: adjustment for repair.
• Voltages and waveforms are dc with respect to ground
under no-signal (detuned) conditions.
no mark : FM
(
no mark : FM
(
) : AM
• Voltages are taken with a VOM (Input impedance 10 M
Ω
).
Voltage variations may be noted due to normal produc-
tion tolerances.
tion tolerances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal produc-
tion tolerances.
tion tolerances.
• Circled numbers refer to waveforms.
• Signal path.
• Signal path.
F
: FM
f
: AM
Note: The components identified by mark
0
or dotted line
with mark
0
are critical for safety.
Replace only with part number specified.
– 17 –
– 18 –
• IC Block Diagrams
– MAIN Board –
– MAIN Board –
IC1
CXA1019M
IC50
BU2614FS
– ANTENNA Board –
IC451
U4226B-MFSG3
VCC
RF IN
GND
3
SB
4
5
6
7
8
9
FLA
FLB
SL
10
1
AGC
AMPLIFIER
POWER
SUPPLY
RECTIFIER &
INTEGRATOR
DECODER
REC
DEC
INT
Q2A
Q2B
Q1A
Q1B
13
12
11
14
TCO
PON
16 15
2
FM IN
PD1
VSS
VDD2
VDD1
AM IN
P2
IF-IN
XOUT
XIN
CE
CK
DA
CD
P0
P1
16
12
13
14
15
8
9
10
11
4
5
6
1
2
3
7
IF
COUNTER
OUTPUT
CONTROL
I/O CONTROL
REGISTER
MAIN CONTROL
PRESCALLER
PHASE
DETECT
•
MAIN BOARD IC100
µ
PD753106GC-064-AB8 (SYSTEM CONTROLLER, LCD DRIVER, KEY CONTROL)
Pin No.
Pin Name
I/O
Description
1
BIAS
O
Liquid crystal display drive bias control output terminal
2 to 4
VLC0 to VLC2
—
Terminal for doubler circuit capacitor connection to develop liquid crystal display drive voltage
5
NC
O
Not used (open)
6
ALM A
O
LED drive signal output of the LCD back light LED (D74)
“H” output at alarm A setting (LED on)
“H” output at alarm A setting (LED on)
7
ALM B
O
LED drive signal output of the LCD back light LED (D75)
“H” output at alarm B setting (LED on)
“H” output at alarm B setting (LED on)
8
KS4
O
Key scan signal output of the key matrix (S101, S201 to S218)
9
VSS
—
Ground terminal
10 to 13
KS0 to KS3
O
Key scan signal output of the key matrix (S101, S201 to S218)
14 to 17
KR0 to KR3
I
Key return signal input of the key matrix (S101, S201 to S218)
18
RESET
I
System reset signal input from the reset signal generator (IC101) “L”: reset
“L” is input for several 100 msec after power on, then it changes to “H”
“L” is input for several 100 msec after power on, then it changes to “H”
19
XT1
I
Sub system clock input terminal (32.768 kHz)
20
XT2
O
Sub system clock output terminal (32.768 kHz)
21
IC
—
Connected to power supply (+3.8V)
22
X1
I
Main system clock input terminal (4.19 MHz)
23
X2
O
Main system clock output terminal (4.19 MHz)
24
VDD
—
Power supply terminal (+3.8V)
25
DATA IN
I
Time code data input from the U4226B (IC451)
26
CLK
O
PLL serial data transfer clock signal output to the FM/AM PLL (IC50)
27
DATA
O
PLL serial data output to the FM/AM PLL (IC50)
28
PDET
I
Power failure detection input terminal “L”: power failure
29 to 31
PI0 to PI2
I
Destination setting terminal
32
TEST
I
Test mode input terminal “L”: test mode Not used (open)
33
MUTE
O
Muting on/off control signal output terminal “L”: muting on
34
CE
O
PLL serial chip enable signal output to the FM/AM PLL (IC50)
35
BZ-CTRL
O
Buzzer control signal output terminal “H” output at alarm B active
36
BUZZER
O
Beep sound (2 kHz) drive signal output to the CXA1019M (IC1)
37 to 60
S23 to S0
O
Segment drive signal output to the liquid crystal display (LCD100)
61 to 64
COM0 to COM3
O
Common drive signal output to the liquid crystal display (LCD100)
4-4.
IC PIN FUNCTION DESCRIPTION
FM FE
TUNING METER
AM IF DET AGC
AF POWER AMP
FM IF
FM/AM
IF OUT
FM RF IN
FE GND
NC
AM RF IN
FM RF
FM OSC
REG OUT
AFC
AM OSC
NF
VOL
FM DISCRI
GND
FM/AM BAND
SELECT
FM IF IN
AM IF IN
NC
METER
IF GND
DET OUT
AFC AGC
AFC AGC
AF IN
RIPPLE FILTER
AF OUT
VCC
GND
AM FE
FM
DISCRIMINATOR
14
13
11
9
8
7
2
1
6
5
3
4
15
16
17
18
19
20
21
22
23
24
25
26
27
28
12
10
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