CASSETTE RECEIVER
KRC-15RG
SERVICE MANUAL
© 2000-10 PRINTED IN KOREA
B51-7684-00 (K) 2161
KRC-179RA/RG/RYA/RYG
KRC-25RA/RG
ANTENNA ADAPTOR
(T90-0523-05)
(Except KRC-281RG)
KRC-279RA/RG/RYA/RYG
KRC-281RG
KRC-279R
CD/MD-CHANGER CONTROL
KRC-25R
CD/MD-CHANGER CONTROL
KRC-15R
KRC-179R
KRC-281R
CD/MD-CHANGER CONTROL
KRC-15RG (E)
KRC-179RA/RG/RYA/RYG (E)
KRC-25RA/RG (E)
PLASTIC CABINET ASSY
(A02-1486-13)
LEVER
(D10-3031-04) x2
MOUNTING HARDWARE ASSY
(J21-9491-13)
DC CORD
(E30-xxxx-xx)
(Refer to the parts list.)
STAY
(J54-0606-04)
SCREW SET
(N99-1610-15)
(KRC-281RG only)
SCREW SET
(N99-1632-05)
(KRC-281RG only)
AUD
1
23
456
CLK
ATT
SRC
PWR
OFF
SCAN
RDM
REP
T.C/D.SCN
M.RDM
LOUD
DISC
HIGH POWER
40Wx
40Wx 4
MENU
FM
AM
FF
REW
PR
OG
VOL ADJ
NAME SET
TI
PTY
AUD
1
23
456
CLK
ATT
SRC
PWR
OFF
SCAN
RDM
REP
T.C/D.SCN
M.RDM
LOUD
DISC
HIGH POWER
40Wx
40Wx 4
MENU
FM
AM
FF
REW
PR
OG
VOL ADJ
NAME SET
TI
PTY
AUD
1
23
456
CLK
ATT
SRC
PWR
OFF
SCAN
RDM
REP
T.C/D.SCN
M.RDM
LOUD
DISC
HIGH POWER
40Wx
40Wx 4
MENU
FM
AM
FF
REW
PR
OG
VOL ADJ
NAME SET
TI
PTY
AUD
1
23
456
CLK
ATT
SRC
PWR
OFF
T.CALL
LOUD
HIGH POWER
40Wx
40Wx 4
MENU
FM
AM
FF
REW
PR
OG
VOL ADJ
TI
PTY
AUD
1
23
456
CLK
ATT
SRC
PWR
OFF
T.C/ALL
LOUD
HIGH POWER
40Wx
40Wx 4
MENU
FM
AM
FF
REW
PR
OG
VOL ADJ
TI
PTY
KRC-279RA/RG/RYA/RYG (E)
KRC-281RG (M)
(KRC-281RG only)
40%
KRC-15R,179R,25R,279R,281R
2
CONTENTS / BLOCK DIAGRAM
CONTENTS / BLOCK DIAGRAM ...............................2
COMPONENT DESCRIPTION...................................3
MICROCOMPUTER'S TERMINAL DESCRIPTION ...4
TEST MODE...............................................................6
ADJUSTMENT............................................................7
PARTS DESCRIPTIONS............................................8
PC BOARD .................................................................9
SCHEMATIC DIAGRAM...........................................13
EXPLODED VIEW ....................................................18
PARTS LIST .............................................................21
SPECIFICATIONS ......................................Back cover
CONTENTS
BLOCK DIAGRAM
IC1
KEY
P
AN
5V
MUTE
B.U.
DET
.
B.U.
ACC
P-CONT
.
MUTE
PRE
POWER
IC
EQ.
AMP
.
CH
ISO
AMP
NC/MPX/
E-VOL.
CD/MD
CHANGER
FRONT
Lch
FRONT
Rch
REAR
Lch
REAR
Rch
J2
LCD
DRIVER
LCD
ME1
MAIN
CASSETTE
MECHA.
IC5
1
Lch
2
Rch
PRE
OUT
IC2
IC4
IC3
SP
OUT
REAR
J4
P
AN
IN
SW
ACC
DET
.
P-CONT
.
J2
J5
IC1
FRONT
-END
J1
FM+B
Q201
AM+B
Q203
AM
BPF
FM
BPF
C154,R206
C153,R207
Q320
Q450,451
Q49
Q50
Q350,351,370
Q53
SW
5V
Q54-57
8V
Q58-61
ILLUMI.
B.U.
5V
Q51,52
SYSTEM
u-COM
S1
S2
S3
RST
SW
Q301
D1-15
PL1,2
ANT
.
TEL
MUTE
DECODER
RDS
IC7
Q501,502
MP
SW
40W
RST
IC
RST
IC6
ED1
FM
ANT
AM
ANT
RF
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
P
.ON
ACC
DET
B.U.
DET
SCL
MUTE
SDA
P
CON
PANEL
RESET
LCLK
LD
ATAS
LD
ATAL
FWD/REV
MOTOR
CHCON
DATA
H
DATA
C
REQH
REQC
CHCLK
Rch
COM
Lch
MP
IN
AM
MPX
OUT
RR
OUT
LR
OUT
RF
Rch
LEVEL
SCL
SDA
OUT
LF
Rch
STBY
MUTE
Rch
Lch
T
-MUTE
FWD
REV
B.U.5V
8V
B.U.
CHRST
SMUTE
8
5
10
B.U.5V
AM+B
VDD
5V
PACK
IN
LRES
PHONE
CHMUTE
BEEP
SVR
AMP
.STBY
SVR
AC
GND
(BEEP)
Lch
Lch
Rch
Lch
1200mV
T
APE
:1681mV
CD/MD-CH
:3529mV
AM
:772mV
FM
:1339mV
8V
RF
GND
OSC
GND
IF2
+B
AUDIO
OUT
8V
S-METER
SD
PLL-SCL
PLL-SDA
M1
HD1
L/R
55.6mV
B.U.5V
SW5V
8V
B.U.5V
AM:
170mV
FM:
213mV
T
APE
P
ACK
IN
(FF/REW)
AMP
.MUTE
FF/REW
B.U.5V
R
QUAL
R
CLK
R
DA
T
A
SW5V
MP
OUT
QUAL
AFC
NOISE
B.U.5V
ILLUMI.
LC
E
(X13)
M
KRC-15R,179R,25R,279R,281R
(E,M)
A1
TEL
DET
D380
5V
R205
3
KRC-15R,179R,25R,279R,281R
COMPONENT DESCRIPTION
REF No.
FUNCTION
OPERATION
IC1
SYSTEM µ-COM
Controls the unit.
IC2
E-VOLUME
Controls the volume and selects source.
IC3
MUTE LOGIC
Controls the mute output.
IC4
POWER AMPLIFIER
For the speaker output.
IC5
EQUALIZER AMPLIFIER
For the cassette tape's signal.
IC6
RESET
Resets the power.
IC7
RDS DECODER
Decodes the radio data.
Q49
ACC DETECTION SW
Outputs "H" during the ACC off.
Q50
BACK-UP DETECTION SW
Outputs "H" when the back-up voltage is under 9.2V.
Q51,52
BACK-UP 5V DRIVER
Works when back-up current exists.
Q53
P.ON 5V SW
Works during the power on.
Q54,55
8V SW
Works during the power on.
Q56,57
8V DRIVER
Works during the power on.
Q58,59
ILLUMI +B SW
Works during the power on.
Q60,61
ILLUMI +B DRIVER
Works during the power on.
Q150
E-VOL MUTE SW
Works when the back-up current is detected
or the changer mute works or system µ-com mute works.
Q151
SVR FORCED DISCHARGE SW
Works when the amplifier mute works.
Q153
PRE OUT MUTE SW
Works when the back-up current is detected
or the changer mute works or system µ-com mute works.
Q201
FM +B SW
Works during FM mode.
Q203
AM +B SW
Works during AM mode.
Q260
MOTOR +B SW
Works during the tape mode.
Q261
MOTOR +B DRIVER
Works when Q206 works.
Q301
CD-CH RESET SW
Works when the power is reset and the reset SW works.
Q320
PANEL 5V SW
Works when the back-up current exists and the panel
is attached on the unit.
Q350
P.CON DRIVER SW
Does not work during the power off and the ALL OFF.
Q351
P.CON PROTECTION SW
Works when the P.CON is short-circuited on the GND.
Q352
P.CON PROTECTION INHIBIT SW
Inhibits the protection SW in a moment during the P.CON on.
Q353
P.CON DRIVER SW
Does not work during the power off and the ALL OFF.
Q450,451
PRE OUT MUTE SW
Works when the back-up current is detected
or the changer mute works or system µ-com mute works.
Q500
AUDIO OUTPUT BUFFER
For RDS decoder.
Q501,502
AFC TIME CONSTANT SW
Works during receiving FM signal.
Q503
NOISE BUFFER
For noise level detection.
SYNTHESIZER UNIT (X14-656x-xx)
KRC-15R,179R,25R,279R,281R
4
MICROCOMPUTER'S TERMINAL DESCRIPTION
PORT No. PORT NAME
I/O
FUNCTION
OPERATING CONDITION
1
PANEL
I
Panel detection.
"L" : Panel exists.
2
L CE
O
LCD driver chip enable.
-
3
L RES
O
LCD driver reset.
-
4
AVSS
-
GND.
-
5
R DATA
I
RDS data.
-
6
R QUAL
I
RDS receiving.
-
7
AVREF 1
-
Reference voltage.
-
8
IC2 SEL 1
I
Selector.
"L" : Normally.
9
IC2 SEL 0
I
Selector.
"L" : Normally.
10
-
-
-
-
11
L DATA L
I
LCD driver communication data.
-
12
L DATA S
O
LCD driver communication data.
-
13
L CLK
O
LCD driver communication clock.
-
14,15
-
-
-
-
16
DATA C
I
Changer communication data.
-
17
DATA H
O
Changer communication data.
-
18
CH CLK
I
Changer communication clock.
-
19-26
-
-
-
-
27
MOTOR
O
Cassette tape motor SW.
-
28
FF/REW
I
Cassette tape FF/REW detection.
"L" : FF or REW works.
29-31
-
-
-
-
32
SD
I
Signal detection.
"H" : Signal exists.
"L" : Signal does not exist.
33
VSS 1
-
GND.
-
34
-
-
-
-
35
PLL CLK
O
Front-end communication clock.
-
36
PLL DATA
I/O
Front-end communication data.
-
37
AM +B
O
AM power supply SW.
-
38
FM +B
O
FM power supply SW.
-
39
IC2 DATA
I/O
E-volume communication data.
-
40
IC2 CLK
O
E-volume communication clock.
-
(X14-) IC1 : µ-COM
KRC-15R,179R,25R,279R,281R
5
MICROCOMPUTER'S TERMINAL DESCRIPTION
PORT No. PORT NAME
I/O
FUNCTION
OPERATING CONDITION
41
AFC
O
FM noise detection / Time constant SW.
-
42
MUTE
O
Mute control.
-
43
AMP MUTE
O
Power amplifier mute.
-
44
-
-
-
-
45
CH CNT
O
Changer control.
-
46
REQ H
O
Changer request.
-
47
-
-
-
-
48
SVR
O
SVR control.
-
49
AMP STBY
O
Power amplifier stand-by.
-
50
BEEP
O
Buzzer signal output.
-
51,52
-
-
-
-
53
P.CONT
O
Power control SW.
-
54
ACC DET
I
ACC detection.
-
55
B.U. DET
I
Back-up detection.
-
56
P.ON
O
Power SW.
-
57
ILLUMI
O
Illumination SW.
-
58
FWD/REV
I
Cassette mechanism FWD/REV detection.
-
59
-
-
-
-
60
RESET
I
System reset signal input.
-
61
SEL 1
I
Destination SW.
-
62
R CLK
I
RDS clock.
-
63
REQ C
I
Changer request.
-
64
PACK IN
I
Cassette tape pack-in detection.
-
65
KEY-REQ
I
Key signal input detection.
-
66
SEL 0
I
Destination SW.
-
67
VSS 0
-
GND.
-
68
VDD 1
-
5V power supply.
-
69
X2
-
Main system clock.
-
70
X1
I
Main system clock.
-
71
IC
-
GND.
-
72
-
-
-
-
73
XT1
-
5V power supply.
-
74
VDD 0
-
5V power supply.
-
75
AVREF 0
I
A/D converter reference voltage.
-
76
S METER
I
S-meter detection.
"H" : S-meter exists.
"L" : S-meter does not exist.
77
PHONE
I
-
Navigation mute : 2.5V or more.
Telephone mute : 1V or less.
78
NOISE
I
FM noise detection.
-
79
AV CONT
O
A/D converter reference voltage.
-
80
-
-
-
-
(X14-) IC1 : µ-COM