CASSETTE RECEIVER
SERVICE MANUAL
© 2000-8 PRINTED IN KOREA
B51-7659-00 (K) 1896
KRC-268A
Plastic cabinet assy
(A02-1486-13)
Lever
(D10-3031-04) x2
Mounting hardware assy
(J21-9491-03)
DC cord
(E30-4790-05)
KRC-268
AUD
1
23
456
CLK
ATT
SRC
PWR
OFF
AME
ADJ
AUTO
T.CALL
LOUD
CRSC
HIGH POWER
40Wx
40Wx 4
A.ADJ
FM
AM
FF
REW
PR
OG
Antenna adaptor
(T90-0523-05)
Escutcheon
(B07-2188-02)
Liquid crystal
(B38-1022-05)
Panel assy
(A64-1946-02)
40%
KRC-268A
2
BLOCK
DIAGRAM
IC1
KEY
PANEL 5V SW
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
TAPE MECHA.
IC5
1 Lch
2 Rch
PRE OUT
IC2
IC4
IC3
SP OUT
REAR
J4
RESET SW
PAN IN SW
ANT-CONT.
P-CONT.
J2
J5
IC1
FRONT-END
J1
FM+B
Q201
AM+B
Q203
AM BPF
FM BPF
C154,157,R206
C153,156,R207
Q320
Q450,451
Q370,371
Q50
Q350-353
Q353
P-CON.SW
Q54-57
COM+B
Q58-61
ILLUMI.
B.U.5V
Q51,52
SYSTEM u-COM
S1
S2
S3
P-CONT.
CHANGER
RST SW
Q301
D1-15
PL1,2
ANT.
ANT-CONT.
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
SW5V
ACC DET
B.U. DET
SCL
MUTE
SDA
P. CON
P
ANEL
HOLD
L
CLK
L
D
ATA
S
L
D
ATA
L
FWD/REV
MOT
OR
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
T-MUTE
FWD
REV
B.U.5V
8V
B.U.
CHRST
S
MUTE
8
4
10
B.U.5V
AM+B
VDD 5V
P
ACK
IN
L
C
E
ANT CON
CHMUTE
BEEP
SVR
AMP. STBY
SVR
AC GND (BEEP)
Lch
Lch
Rch
Lch
1200mV
TAPE :1681mV
CD/MD-CH :3529mV
AM :546mV
FM :1781mV
8V
RF GND
OSC GND
IF2 +B
AUDIO OUT
8V
S-METER
SD
PLL CLK
PLL DATA
M1
HD1
R
55.6mV
BU5V
SW5V
8V
B.U.5V
AM: 170mV
FM: 400mV
L
PACK IN
(FF/REW)
AMP. MUTE
FF/REW
BU5V
ILL
(X13)
M
A1
KRC-268A
3
COMPONENT DESCRIPTION
SYNTHESIZER UNIT (X14-614x-xx)
REF. No.
FUNCTION
OPERATION
IC1
SYSTEM
µ-COM
Controls system.
IC2
ELECTRIC VOLUME
Controls sound volume. Selects each source.
IC3
MUTE
Controls each mute output.
IC4
POWER IC
Amplifies power so that the speaker can drive audio signal.
IC5
EQUALIZER AMPLIFIER
Equalizer amplifier for cassette tape sound.
Q50
BACK-UP DETECTION
Stops when the back-up voltage comes less than 9.2V.
Q51,52
BACK-UP 5V AVR
Works when the back-up works.
Q53
P.ON DRIVER
Works when the power comes.
Q54,55
COM+B SW
Works when 5V comes.
Q56,57
COM+B AVR
Works when Q54 and Q55 work.
Q58,59
ILLUMINATION +B SW
Works when the base level of Q58 comes "H".
Q60,61
ILLUMINATION +B AVR
Works when Q58 and Q59 work.
Q150
ELECTRIC VOLUME MUTE SW
Works when the base level comes "H".
Q151
SVR DISCHARGE SW
Works when the base level comes "H".
Q153
PRE MUTE DRIVER
Works when the base level comes "L".
Q200
FM +B SW
Works when the base level comes "H" in FM mode.
Q201
FM +B DRIVER
Works when Q200 works.
Q202
AM +B SW
Works when the base level comes "H" in AM mode.
Q203
AM +B DRIVER
Works when Q203 works.
Q260
MOTOR +B SW
Works when the base level comes "H" in the tape mode.
Q261
MOTOR +B DRIVER
Works when Q260 works.
Q301
CHANGER RESET SW
Works when the base level comes "L".
Q320
PANEL 5V SW
Works when the base level comes "L".
Q350
P-CON. DRIVER
Works when Q353 works.
Q351,352
P-CON. PROTECTION
Works when P-CON output voltage goes down.
Q353
P-CON. SW
Works when the base level comes "H".
Q370
ANTENNA CONTROL DRIVER
Works when Q371 works.
Q371
ANTENNA CONTROL SW
Works when the base level comes "H" in the tuner mode.
Q450,451
PRE MUTE SW
Works when Q153 works.
CIRCUIT DESCRIPTION
(X14-) IC1 :
µ-COM
PORT No.
PORT NAME
I/O
FUNCTION
OPERATING CONDITION
1
XIN
I
µ-com clock. (4.5MHz)
-
2
GND
-
GND.
-
3
L DATA L
I
LCD driver data.
-
4
L DATA S
O
LCD driver data.
-
5
L CLK
O
LCD driver clock.
-
6
L CE
O
LCD driver chip enable.
-
7
SDA
I/O E-volume data.
-
8
PLL DATA
I/O Tuner data.
-
9
PLL CLK
O
Tuner clock.
-
10
SD
I
Tuner signal detection.
"H" : Tuner signal exists.
"L" : Tuner signal does not exist.
11
DATA C
I
Changer data.
-
12
DATA H
O
Head unit data.
-
13
CH CLK
I/O Changer clock.
-
14
-
-
No connection.
-
15
MOTOR
O
Mechanism motor.
-
16
SCL
O
E-volume clock.
-
17-24
-
-
No connection.
-
25
AM+B
O
AM power supply.
-
26
FM+B
O
FM power supply.
-
27
PACK IN
I
Cassette tape pack-in.
"L" : Pack in.
"H" : Ejection.
28
FF/REW
I
FF/REW signal.
"L" : FF/REW.
"H" : Play.
29,30
GND
-
GND.
-
31
VDD
-
VDD.
-
32
REQ C
I
Request from changer.
-
33
MUTE
O
Mute.
-
34
CH CON
O
Changer control.
-
35
REQ H
O
Request to head unit.
-
36
SVR
O
Power IC (IC4) discharge control.
-
37
AMP STBY
O
Power IC (IC4) stand-by.
-
38
AMP MUTE
O
Power IC (IC4) mute.
-
39
P CON
O
P.CON for external amplifier.
-
40
ANT. CON
O
Power antenna.
-
41
SW5
O
Circumambient circuit power supply control.
-
42
ILL
O
Illumination.
-
43
-
-
No connection.
-
44
BEEP
O
Buzzer. (2KHz)
-
45-47
-
-
No connection.
-
48
ROLL OFF
I
Destination switch.
-
49
N.CAN
I
Destination switch.
-
50
SEL1
I
Destination switch.
-
51
SEL2
I
Destination switch.
-
52
--
No connection.
-
53
EQ MUTE
O
Tape equalizer mute.
-
54
FWD/REV
I
FWD/REV.
-
55
-
-
No connection.
-
56
REMO
I
Remote control.
-
57-60
-
-
No connection.
-
61
ACC DET
I
ACC detection.
-
62
BU DET
I
Back-up detection.
-
63
S METER
I
Tuner signal meter.
-
64
PANEL
I
Panel on/off.
"L" : Panel on.
"H" : Panel off.
65,66
GND
-
GND.
-
67
HOLD
I
Clock stop.
-
68
VDD
-
VDD.
-
69,70
GND
-
GND.
-
71,72
-
-
No connection.
-
73
VDD
-
VDD.
-
74,75
GND
-
GND.
-
76
VSS
-
GND.
-
77,78
-
-
No connection.
-
79
GND
-
GND.
-
80
XOUT
O
µ-com clock. (4.5MHz)
-
KRC-268A
4
TEST MODE
1. How to enter the test mode
· Reset the unit while holding the "FM" key and preset "6" key.
· All indication segments go ON at the beginning of the test mode.
2. How to release the test mode
· Simply reset the unit.
· (NOTE) The test mode is not canceled by ACC OFF, power OFF, momentary power
down or the panel off.
3. Audio adjustment
· Set the volume level to -10dB (which is shown as "30" on the display).
· Loudness OFF.
· The BASS/TREBLE and BALANCE/FADER can be set to the full-boost/full-cut and full-
front/full-rear each by pressing the "Track UP" / "Track DOWN" keys.
· Sound coordination doesn't appear for the feed.
5
KRC-268A