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CASSETTE RECEIVER
KRC-225/235
SERVICE MANUAL
© 2001-11 PRINTED IN KOREA
B51-7854-00 (K) 1748
KRC-265/S
KRC-265/S
KRC-235
KRC-225
Panel assy
(A64-2505-02)
Plastic cabinet assy
(A02-1486-13)
Lever
(D10-3031-04)x2
Mounting hardware assy
(J21-9491-13)
DC cord
(E30-4783-05):KRC-225/235
DC cord
(E30-4784-05):KRC-265/S
Screw set
(N99-1610-15)
Screw set
(N99-1719-05)
Escutcheon
(B07-2124-02)
Panel assy
(A64-2506-02)
Escutcheon
(B07-2124-02)
Panel assy
(A64-2507-02):KRC-265
(A64-2634-02):KRC-265S
Escutcheon
(B07-2124-02):KRC-265
(B07-3049-02):KRC-265S


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KRC-225/235/265/265S
2
BLOCK
DIAGRAM
IC1
KEY
PAN 5V
MUTE
B.U. DET.
B.U.
ACC
P-CONT.
MUTE
PRE
POWER IC
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
MAIN
TAPE MECHA.
IC5
1 Lch
2 Rch
PRE OUT
IC2
IC4
IC3 Q150,153
SP OUT
REAR
J4
RST
PAN IN SW
ANT-CONT.
P-CONT.
J2
Q370,371
Q450,451
Q50
Q350-353
Q58-61
Q54-57
Q53
Q320
Q301
Q51,52
J5
IC1
ED1
FM+B
Q200,201
AM+B
Q202,203
AM BPF
FM BPF
SW 5V
COM +B
ILLUMI.
B.U.5V
SYSTEM MI-COM
RST SW
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
B.U.
8V
B.U.
CHRST
S
MUTE
8
4
6
5
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
HEAD
PLAY
R
55.6mV
BU5V
SW5V
8V
B.U.5V
AM: 170mV
FM: 400mV
L
PACK IN
(FF/REW)
AMP. MUTE
FF/REW
BU5V
ILL
P-CONT.
/ANT-CONT.
(X16-)
(X14-)
M
KRC-265/S
KRC-225/235
KRC-235,265/S
A1
MOTOR SW
Q260,261
ACC. DET.
5V
Q1
,Q151


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KRC-225/235/265/265S
3
COMPONENT DESCRIPTION
Ref.No.
Component Name
Application/Function
Operation/Condition/Compatibility
IC1
LC72366-9592
System MI-COM.
System control
IC2
TDA7461ND
E-VOL. & N.C. MPX
Controls sound volume. Selects each source.
IC3
HD74HC27FP
Mute logic
3-input NOR gate x 3
IC4
TDA7384A or
Power IC
Amplifies power so that the speaker can drive audio signal.
TDA7386
IC5
LA3161
Equalizer amplifier
Equalizer amplifier for cassette tape sound
2SC2412K or
BACK-UP detection
While BACK-UP is added, a base becomes Hi, and Q50 is
Q50
2SD601A
(Momentary power down
turned on.
detection) SW
Q51
2SB1443
While BACK-UP is added, AVR outputs +5V.
Q52
2SC2412K or
BACK-UP 5V AVR
Q51 and Q52 is inverted Darlington connection.
2SD601A
Q53
DTA114YK or UN2114
P.ON 5V SW
While a base becomes Lo, Q53 is turned on.
or KRA107S
Q54
DTC144EK or UN2213
While Q54's base becomes Hi, Q55 is turned on.
or KRC104S
COM+B SW
Q55
DTA124EK or UN2112
Works during POWER ON mode.
or KRA103S
2SA2057 or 2SB1548
Q56
(P) or 2SB1565(E,F)
While Q57's base becomes Hi, Q56 is turned on.
or 2SB1655(E,F)
COM+B AVR
Q57
2SC2412K or
Q56 and Q57 is inverted Darlington connection.
2SD601A
Q58
DTC144EK or UN2213
While Q58's base becomes Hi, Q59 is turned on.
or KRC104S
Illumination +B SW
Q59
DTA124EK or UN2112
Works during POWER ON mode with a panel attached
or KRA103S
to the set.
2SA2057 or 2SB1548
Q60
(P) or 2SB1565(E,F)
While Q61's base becomes Hi, Q60 is turned on.
or 2SB1655(E,F)
Illumination +B driver
Q61
2SC2412K or
Q60 and Q61 is inverted Darlington connection.
2SD601A
DTC124EK or UN2212
When BACK-UP detection SW or CHANGER RESET SW or
Q150
or KRC103S
Electric volume mute SW
MI-COM.'s mute works, a base becomes Hi, and Q150
is turned on.
Q151
DTC114YK or UN2214
SVR discharge SW
When POWER IC RESET is activated, a base becomes Hi,
or KRC107S
Q151 is turned on.
DTA124EK or UN2112
When BACK-UP detection SW or CHANGER RESET SW or
Q153
or KRA103S
Pre-out mute driver
MI-COM.'s mute works, a base becomes Lo, and Q153
is turned on.
Q200
DTC124EK or UN2212
Q201 is turned on when Q200's base becomes Hi.
or KRC103S
FM +B SW
Q201
2SB1277(Q,R)
Works during FM reception mode.
Q202
DTC124EK or UN2212
Q203 is turned on when Q202's base becomes Hi.
or KRC103S
AM +B SW
Q203
2SB1277(Q,R)
Works during AM reception mode.
SWITCH UNIT(X16-1490-XX)
Ref.No.
Component Name
Application/Function
Operation/Condition/Compatibility
IC1
LC75853NE
LCD driver with key-matrix
Q1
DTA114EK or UN2111
Key-matrix permission SW Ready on key-matrix
or KRA102S
SYNTHESIZER UNIT(X14-6850-XX)


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KRC-225/235/265/265S
4
COMPONENT DESCRIPTION
Ref.No.
Component Name
Application/Function
Operation/Condition/Compatibility
Q260
DTC114YK or UN2214
When Q260's base becomes Hi, Q261 is turned on.
or KRC107S
Motor +B SW
Q261
2SB1443
Works during TAPE mode.
Q301
DTA144EK or UN2113 Changer reset SW
When a base becomes Lo, Q301 is turned on.
Q320
2SA1037K
Panel 5V SW
While a panel is attached to the set, a base becomes Lo, and
Q320 is turned on.
Q350
2SB1277(Q,R)
P-CON. driver
When Q353's base becomes Hi, Q350 is turned on.
Q351
2SA1037K
P-CON. protection SW
Works when P-CON is being short-circuited on GND.
Q352
DTA124EK or UN2112 P-CON. protection
Inhibits protection SW function when P-CON works momentary.
or KRA103S
inhibit SW
Q353
DTC114YK or UN2214
P-CON. SW
Q353 is turned on when a base becomes Hi. Works during
or KRC107S
POWER ON mode.
Q370
2SB1277(Q,R)
Q370 is turned on when Q371's base becomes Hi.
Q371
DTC114YK or UN2214 ANT-CON. SW
Works during TUNER mode.
or KRC107S
Q450
DTC143TK or UN2216 Pre-out mute SW (R ch.)
When BACK-UP detection SW or CHANGER RESET SW or
Q451
DTC143TK or UN2216 Pre-out mute SW (L ch.)
MI-COM.'s mute works, a base becomes Hi, and Q450,451
are turned on.
SYNTHESIZER UNIT(X14-6850-XX)


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KRC-225/235/265/265S
5
MICROCOMPUTER'S TERMINAL DESCRIPTION
Pin No.
Pin Name
I/O
Description
Processing Operation
1
XIN
I
Main clock resonator connection terminal
2
GND
-
TEST terminal 2
Connected to GND lines.
3
L DATA L
I
Data input from the LCD driver IC
4
L DATA S
O
Data output to the LCD driver IC
5
L CLK
O
Clock output to the LCD driver IC
6
L CE
O
CE output to the LCD driver IC
7
SDA
I/O Data input/output with the E-VOL. IC
8
PLL DATA
I/O Data input/output with the F/E
9
PLL CLK
O
Clock output to the F/E
10
SD
I
SD input from the F/E
Hi : Station detected
11
DATA C
I
Data input from changers
12
DATA H
O
Data output to changers
13
CH CLK
I/O Clock input/output with changers
14
-
O
-
N.C.(Not used)
15
MOTOR
O
Cassette motor on/off output
Hi : Motor ON
16
SCL
O
Clock output to the E-VOL. IC
17-24
-
O
-
N.C.(Not used)
25
AM+B
O
AM+B ON/OFF output
Hi : during AM reception
26
FM+B
O
FM+B ON/OFF output
Hi : during FM reception
27
PACK IN
I
Cassette tape Pack-in detection input
Lo : Pack-in
28
FF/REW
I
FF/REW detection input
Lo : FF/REW, Hi : PLAY
29
GND
I
-
Connected to GND lines.
30
GND
I
-
Connected to GND lines.
31
VDD
-
Positive power supply connection terminal Connected to B.U. 5V lines.
32
REQ C
I
Request input from changers
Lo : Request
33
MUTE
O
Audio mute on/off output
Hi : Mute ON
34
CH CON
O
Changer control
Lo : Standby, Hi : ON
35
REQ H
O
Request output to changers
Lo : Request
When the momentary power down, after ACC
36
SVR
O
Power IC reset terminal
ON/OFF is detected and after POWER OFF,
the output becomes Hi temporarily.
37
AMP STBY
O
Power IC standby control output
Hi : POWER ON mode
38
AMP MUTE
O
Power IC mute control
Lo : Mute
39
P CON
O
Power control
Hi : POWER ON mode
40
ANT CON
O
Antenna control
Hi : during FM/AM reception
41
SW5V
O
SW 5V control
Lo : POWER ON mode
42
ILL
O
Illumination AVR ON/OFF control terminal
Hi : POWER ON mode
43
-
O
-
N.C.(Not used)
44
BEEP
O
BEEP sound output
45-47
-
O
-
N.C.(Not used)
48
ROLL OFF
I
Roll off input
Pull down to GND lines. (Not used)
49
NOISE
I
Noise canceller input
Pull down to GND lines. (Not used)
CANCELLER
50
SEL1
I
Destination input 1
Lo : KDC-225, Hi : KDC-235,265/S
51
SEL2
I
Destination input 2
Lo : KDC-265/S, Hi : KDC-225,235
52
SEL3
O
Destination input 3
N.C.(Not used)
53
EQ MUTE
O
Tape equalizer mute on/off output
N.C.(Not used)
54
FWD/REV
I
FWD/REV mode detection input
Lo : REV mode
55
-
O
-
N.C.(Not used)
56
REMO
I
Data input from the remote control
KDC-225/235:Pull up to PON5V lines. (Not used)
light sensor
KDC-265/S:Pull down to GND lines. (Not used)
57-60
-
O
-
N.C.(Not used)
Terminal Description ( IC1 : X14-6850-XX)