CASSETTE RECEIVER
KRC-478R/RV/RY/RYV
SERVICE MANUAL
© 1999-11 PRINTED IN KOREA
B51-7567-00 (K) 1894
KRC-478R/RV/RY/RYV (E)
MECHANISM EXTENSION CORD
W05-0477-00 (7P)
W05-0609-00 (10P)
SRC
PWR
OFF
TI
LOUD
EJECT
/ PTY
VOL ADJ
MENU
CLK
NAME.S
SCAN
B.S/RDM
REP
D.SCN
M.RDM
KRC-478R
40W 4
X
CD MD-CHANGER CONTROL
DISC
DISC
ANTENNA ADAPTOR
(T90-0523-05)
PLASTIC CABINET ASSY
(A02-1486-13)
LEVER
(D10-xxxx-xx) x2
MOUNTING HARDWARE ASSY
(J21-9491-03)
(Refer to the parts list.)
DC CORD
(E30-4792-05)
(KRC-478R/RY only)
40%
KRC-478R/R
V/R
Y/R
YV
2
BLOCK
DIAGRAM
IC8
RDS
DECODER
IC1
KEY
PANEL 5V
MUTE
B.U DET.
B.U
ACC
P-CONT.
MUTE
PRE OUT
POWER IC
MOTOR
DRIVER
IC6
EQ. AMP
CH. ISO AMP.
N.C/MPX
E-VOL.
CD/MD
CHANGER
FRONT Lch
FRONT Rch
REAR Lch
REAR Rch
J2
LCD DRIVER
LCD
ME1
MAIN
SUB
IC5
1 Lch
2 Rch
PRE OUT
IC2
IC4
IC10
SP OUT
REAR
SUB
J4
DSI
REMOTE
RESET SW
PANEL SW (GND)
GRN/RED
u-COM
RESET
IC9
ACC DET.
P-CONT.
TEL MUTE
J2
J5
DRIVER
Lch
Rch
PRE OUT
FRONT
CN3
IC1
(40W)
FRONT-END UNIT
J1
FM+B
Q61,63
AM+B
Q62,64
5V
R216
AM BPF
FM BPF
R205,C207,211
R206,C206,212
MP SW
IC2
Q65
Q20
u-COM
RESET
D18,19
Q21
Q2,3
D1-17
Q57-60
Q18
Q19
Q14-17
Q3
SW5V
Q4,5
SW14W
Q6,7
8V AVR
Q10-13
ILLUMI.
AVR
AVR
B.U.5V
Q1,2
u-COM
ED1
DRIVER
FM ANT
AM ANT
OSC GND
FM+B
AM+B
OSC GND
OSC GND
OSC GND
VT
PLL +B
IFC OUT
SDA
SCL
DIG GND
IF1+B
IF1 GND
S-METER
IF2 GND
SD
FM+B
SUB+
SUB-
PON
ACC DET
B.U DET
SCL
MUTE
SDA
P CON
P
ANEL
RESET
L-RESET
L-CLK
L-D
A
T
A
S
L-D
A
T
A
L
DSI
FWD/REV
T
-MODE
M
OTO
R
CH
CON
D
ATA
H
D
ATA
C
REQ
H
REQ
C
CH
CLK
Rch
COM
Lch
TAPE
MP IN
AM
MPX
OUT RR
OUT LR
OUT RF
Rch
LEVEL
SCL
SDA
OUT LF
Rch
STBY
MUTE
Rch
Lch
PACK
T-END
SYBY
MODE
FWD
REV
B.U.5V
8V
B.U
CHRST
SMUTE
8V
8
5
10
IN
B.U.5V
AM+B
VDD 5V
R QUAL
R CLK
R DATA
P
A
CK
IN
T
-END
L-CE
B.U.5V
REMO
TE
SW5V
GRN
RED
PHONE
CHMUTE
BEEP
SVR
STBY
SVR
AC GND(BEEP)
Lch
Lch
Rch
Lch
1200mV
3
2
1
TAPE :1778mV
CD/MD-CH :3592mV
AM :792mV
FM :1276mV
SW 5V
MUSIC
MUSIC
8V
RF GND
OSC GND
IF2 +B
AUDIO OUT
8V
S-METER
SD
PLL-SCL
PLL-SDA
M2
M1
Ref.103
Ref.94
Ref.95
Ref.105
Ref.102
HD1
AFC
NOISE
QUAL
MPOUT
R
MUTE
EQ
MUTE
340mV
M-STBY
B.U.5V
B.U.5V
SW5V
8V
B.U.5V
AM: 175mV
FM: 213mV
L
(X13)
M
M
A1
KRC-478R/RV/RY/RYV (E/E/E/E)
KRC-478R/RV/RY/RYV
3
COMPONENT DESCRIPTION
SYNTHESIZER UNIT (X14-6xxx-xx)
REF.
No.
FUNCTION
OPERATION
IC1
-COM
Controls system.
IC2
ELECTRIC VOLUME
Switches each source, decodes FM stereo signal, controls sound.
IC4
POWER IC
Amplifies power so that the speaker can drive audio signal.
IC5
EQUALIZER AMPLIFIER
Amplifies and equalizes the cassette head output signal (120
sec).
IC6
SUB MOTOR CONTROLLER
Controls sub motor's loading and eject modes.
IC8
RDS DECODER
Decodes RDS signal from tuner MPX signal.
IC9
-COM RESET
Resets
-COM after detecting the back-up voltage comes
less than 3V.
IC10
MUTE DRIVER
Mutes power IC (IC4) and E-volume (IC2) when the back-up is
detected and
-COM mute signal is output.
Q1,2
BACK-UP 5V AVR
Usually output 5V when battery is connected.
Q3
SW 5V
Outputs 5V when
-COM makes Q3's base level "L".
Q4,5
SW 14V
Q4's corrector outputs the back-up 14V when
-COM makes Q5's
base level "H".
Q6,7
8V AVR
Output 8V.
Q8,9
MAIN MOTOR SW
Output 14V when
-COM makes Q9's base level "H".
Q10-13
ILLUMINATION AVR
Q12's corrector outputs 10.3V when
-COM makes Q11's
base level "H".
Q14
P-CON. START-UP
Cancels Q15's protection circuit effected by C9 time constant and
Q14's inner base resister.
Q15
P-CON. PROTECTION CIRCUIT
Stops output signal, and makes Q16's base level "H" when P-CON
output comes GND shorted.
Q16,17
P-CON. SW
Outputs the back-up 14V when Q17's base level comes "H".
Q18
ACC DETECTION
Corrector level comes "L" when ACC comes "ON".
Detection voltage : 8.95V.
Q19
BACK-UP DETECTION
Corrector level comes "L" when the back-up comes "ON".
Detection voltage : 9.0V.
Q20
-COM RESET
Resets
-COM when Q20's base level comes "H".
Q21
DSI
Indicates when Q21's base level comes "H".
Q51
POWER AMPLIFIER SVR CONTROLLER
SVR level comes "L" when
-COM makes Q51's base level "H".
Q52
PREOUT MUTE CONTROLLER
Mutes preout sound when Q52's base level comes "L".
Q53
ELECTRIC VOLUME MUTE
Mutes E-volume (IC2) signal when Q53's base level comes "H".
Q54,55
AFC
Switches AFC time constant.
Q56
MPX BUFFER
For the front-end MPX output buffer (Emitter follower).
Q57-60
PREOUT MUTE CONTROLLER
Mutes preout sound when Q52's base level comes "L".
Q61
FM+B SW
"ON" when Q61's base level comes "H".
Q62
AM+B SW
"ON" when Q62's base level comes "H".
Q63
FM+B SW
"ON" when Q61's base level comes "H".
Q64
AM+B SW
"ON" when Q62's base level comes "H".
Q65
PANEL SW
"ON" when Q65's base level comes "L" (Panel OFF).
Q67
NOISE BUFFER
For E-volume (IC2) output buffer (Emitter follower).
KRC-478R/RV/RY/RYV
4
CIRCUIT DESCRIPTION
(X14-) IC1 :
-COM
PORT
No.
PORT NAME
I/O
FUNCTION
OPERATING CONDITION
1
AV CONT
O
Analogue reference voltage control.
Active "H".
2
IC2 TYPE O
I
Stereo signal data switch.
-
3
IC2 TYPE 1
I
Stereo signal data switch.
-
4
AVSS
-
Analogue GND.
-
5
MOTOR
O
Cassette mechanism power supply control.
"H" : Mechanism motor +B "ON".
"L" : Mechanism motor +B "OFF".
6
M-STBY
I
Stand-by signal input from the cassette mechanism.
"H" when the stand-by signal exists.
"L" when the other signal exists.
7
AV REF 1
-
5V power supply for D/A converter reference voltage.
-
8
ILLUMI
O
Illumination power supply control.
"H" : Illumi. "ON" or the ALL OFF mode.
"L" : Illumi. "OFF".
9
L-RESET
O
Reset signal output to LCD driver (X13-).
"L" : Reset.
10
PANEL
I
Panel detection signal input.
"H" : Panel OFF.
"L" : Panel ON.
11
L-DATA L
I
Data input from LCD driver.
-
12
L-DATA S
O
Data output from LCD driver.
-
13
L-CLK
O
Data clock output from LCD driver.
-
14,15
N.C.
-
-
-
16
CH-DATA C
I
Data input from the changer.
-
17
CH-DATA H
O
Data output to the changer.
-
18
CH-CLK
I/O Changer communication clock input and output.
-
19
L-CE
O
LCD driver data control.
Active "H".
20
SUB+
O
Sub motor control signal output.
-
21
SUB-
O
Sub motor control signal output.
-
22
MS-CONT
O
No audio signal detection level switch to equalizer amplifier.
"H" : PLAY.
"L" : FF/REW.
23
EQ-MUTE
O
Mute control signal output to equalizer amplifier.
"H" : FF/REW or the other source.
"L" : TAPE PLAY.
24
PLL-SCL
O
Communication clock signal output to the front-end.
-
25
AM+B
O
Front-end's AM power supply control output.
"H" : AM+B "ON".
26
FM+B
O
Front-end's FM power supply control output.
"H" : FM+B "ON".
27
N.C.
-
-
-
28
DSI
O
DSI's LED on/off switch.
"H" : LED "ON".
29
MUSIC
I
No audio signal detection level input to equalizer amplifier.
"H" when audio signal does not exist.
"L" when audio signal exists.
30
FWD/REV
I
Tape FWD/REW signal input.
"H" : Forward.
"L" : Reverse.
31
R-DATA
I
Data input from RDS decoder.
-
32
R-QUAL
I
Qual input from RDS decoder.
-
33
VSS1
-
GND.
-
34
SD
I
SD signal input from the front-end.
"H" when the carrier signal exists.
"L" when the carrier signal does not exist.
35
IC2-SCL
O
Clock output to E-volume (IC2).
-
36
N.C.
-
-
-
37
PLL-SDA
I/O Data input and output to the front-end.
-
38
IC2-SDA
I/O Data input and output to E-volume (IC2).
-
39
MUTE
O
Preout and mute signal output to E-volume (IC2).
"H" : Mute "ON".
"L" : Mute "OFF".
40
N.C.
-
-
-
KRC-478R/RV/RY/RYV
5
CIRCUIT DESCRIPTION
(X14-) IC1 :
-COM
PORT
No.
PORT NAME
I/O
FUNCTION
OPERATING CONDITION
41
AFC
O
Noise detection time constant switch.
"L" : FM seeking.
"H" : The other condition.
42-44
N.C.
-
-
-
45
P-MUTE
O
Mute signal output to the power IC (IC4).
"L" : Power IC (IC4) mute.
46
SVR
O
SVR signal output to the power IC (IC4).
"L" when P.ON goes down.
47
STBY
O
Stand-by signal output to the power IC (IC4).
"H" : Power IC (IC4) "ON".
"L" : Power IC (IC4) "OFF".
48
P-CON
O
Control signal output to P-CON or P-ANT.
"H" : P-CON signal output "ON".
"L" : P-CON signal output "OFF".
49
N.C.
-
-
-
50
BEEP
O
Buzzer signal output.
Beep sound output.
51
ACC-DET
I
ACC detection signal input.
"H" : ACC "OFF".
"L" : ACC "ON".
52
BU-DET
O
Back-up voltage detection signal input.
"H" when back-up signal does not exist.
"L" when back-up signal exists.
53
CH-REQ H
O
Request signal output to the changer.
"L" : Request.
54
CH-CON
O
Changer control.
"H" : Changer mode.
"L" : The other mode.
55
N.C.
-
-
-
56
SW5
O
SW 5V power control signal output.
"L" : SW 5V "ON".
57
P.ON
O
P.ON power supply control signal output.
"H" : Power "ON".
"L" : Power "OFF".
58,59
--
-
-
60
RESET
I
System reset signal input.
"L" : Reset.
"H" : The other condition.
61
REMOTE
I
Data input from the remote controller.
-
62
R-CLK
I
Data clock input from RDS decoder .
-
63
CH-REQ C
I
Request input signal from the changer.
-
64
PACK IN
I
Insertion detection signal input from cassette mechanism.
"H" : Pack in.
"L" : Pack out.
65
KEY-REQ
I
Key request.
Active "L".
66
T-END
I
Tape-end detection signal input from cassette mechanis.
"H" : Tape running.
"L" : Tape-end.
67
VSS 0
-
GND.
-
68
VDD 1
-
Power supply.
-
69
X2
-
For main system clock oscillation.
-
70
X1
I
For main system clock oscillation.
-
71
IC/TEST
-
For flash memory writing.
-
72
XT2
-
-
-
73
VDD 0
-
Power supply.
-
74
VDD 0
-
Power supply.
-
75
AV REF 0
I
5V power supply (For A/D converter reference voltage).
-
76
S-METER
I
S-meter voltage input from the front-end.
"H" : SD signal exists.
"L" : SD signal does not exist.
Vth : Fit the new front-end.
77
T-MODE
I
Tape mode input from cassette mechanism.
Vth : 2.5V.
78
PHONE
I
Phone (Tel-mute) voltage input.
Tel mute : More than 1V.
Navi mute : Less than 2.5V.
79
NOISE
I
Voltage input from E-volume (IC2)'s noise amplifier.
-
80
TYPE 0
I
Destination switching.
"H" : KRC-478RV/RYV.
"L" : The other models.