Kenwood KRC-20SA User manual

©2002-1 PRINTED IN JAPAN
B51-7881-00 (N)1924
CASSETTE RECEIVER
KRC-20SA/G
SERVICE MANUAL
40Wx4
HIGH POWER
KRC-20S
LOUD
PWR
OFF
AMEAUTO ADJ
CLK
SRC
AUD
T. CALL
A. ADJ
CRSC
REW
PR FF OG
Lever
(D10-3031-04)x2
Plastic cabinet assy
(A02-1486-13)
Escutcheon
(B07-2124-02)
Knob (ATT)
(K25-1388-03)
Cassette lid
(A53-1638-13) Panel assy (A64-2519-02)
Mounting hardware assy
(J21-9491-13)
DC cord
(E30-4959-05)
Antenna adaptor
(T90-0523-05)

KRC-20SA/G 2
BLOCK DIAGRAM
IC1
KEY
PAN 5V
MUTE
B.U. DET. B.U.
ACC
POWER IC
EQ. AMP.
CH ISO AMP
NC/MPX/
E-VOL.
FRONT Lch
FRONT Rch
REAR Lch
REAR Rch
J2
LCD DRIVER
LCD
MAIN
TAPE MECHA.
IC5
IC2 IC4, Q151
IC3,Q150
SP OUT
PAN IN SW ACC DET.
P-CONT.
J2
IC1
FM+B
Q200,201
AM+B
Q202,203
AM BPF
FM BPF
Q320
Q50
Q350-353
Q53
SW 5V
Q54-57
COM+B
Q58-61
ILLUMI.
B.U. 5V
Q51,52
SYSTEM u-COM
RST SW
Q301
MOTOR SW
RST
Q260,261
ED1 Q1
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
PANEL HOLD L CLK L DATA S L DATA L FWD/REV MOTOR
Rch
COM
Lch
MP IN
AM
MPX
OUT RR
OUT LR
OUT RF
LEVEL
SCL
SDA
OUT LF
STBY
MUTE
Rch
Lch
T-MUTE
FWD
REV
B.U.5V
B.U.
8V B.U.
S MUTE
4
65
B.U.5V
AM+B
VDD 5V
PACK IN L RES
ANT CON
BEEP
SVR
AMP. STBY
SVR
AC GND (BEEP)
Rch Lch
8V
RF GND
OSC GND
IF2 +B
AUDIO OUT
8V
S-METER
SD
PLL CLK
PLL DATA
PLAY
HEAD
R
L
55.6mV
B.U.5V
SW5V
8V
B.U.5V
AM: 170mV
FM: 400mV
TAPE
PACK IN
(FF/REW)
AMP. MUTE
FF/REW
B.U.5V
ILLUMI.
(X16- )
(X14- )
M
A1
5V
D200
P-CONT.
/ANT-CONT.

KRC-20SA/G
3
● SWITCH UNIT (X16-1492-XX)
COMPONENTS DESCRIPTION
Ref.No.
Component Name Application/Function Operation/Condition/Compatibility
IC1 LC75853NE LCD driver with key-matrix
Q1
DTA114EK or UN2111 or
KRA102S
Key-matrix permission SW Ready on key-matrix
● SYNTHESIZER UNIT (X14-6852-71)
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 ×3
IC4 TDA7384A Power IC Amplifies power so that the speaker can drive audio signal.
IC5 LA3161 Equalizer amplifier Equalizer amplifier for cassette tape sound
Q50
2SC2412K or 2SD601A
BACK-UP detection
While BACK-UP is added, a base becomes Hi, and Q50 is
(Momentary power down detection) SW turned on.
Q51 2SB1443 BACK-UP 5V AVR While BACK-UP is added, AVR outputs +5V.
Q52
2SC2412K or 2SD601A Q51 and Q52 is inverted Darlington connection.
Q53
DTA114YK or UN2114 or
KRA107S
P.ON 5V SW While a base becomes Lo, Q53 is turned on.
Q54
DTC144EK or UN2213 or
KRC104S
COM+B SW While Q54's base becomes Hi, Q55 is turned on.
Q55
DTA124EK or UN2112 or
Works during POWER ON mode.
KRA103S
2SA2057 or 2SB1548 (P) or
Q56
2SB1565(E,F) or While Q57's base becomes Hi, Q56 is turned on.
2SB1655(E,F)
COM+B AVR Q56 and Q57 is inverted Darlington connection.
Q57 2SC2412K or 2SD601A
Q58
DTC144EK or UN2213 or
KRC104S
Illumination +B SW While Q58's base becomes Hi, Q59 is turned on.
Q59
DTA124EK or UN2112 or
Works during POWER ON mode with a panel
KRA103S
attached to the set.
2SA2057 or 2SB1548 (P) or
Q60 2SB1565(E,F) or While Q61's base becomes Hi, Q60 is turned on.
2SB1655(E,F)
Illumination +B driver Q60 and Q61 is inverted Darlington connection.
Q61 2SC2412K or 2SD601A
DTC124EK or UN2212 or
When BACK-UP detection SW or CHANGER RESET SW or
Q150
KRC103S
Electric volume mute SW MI-COM.'s mute works, a base becomes Hi, and Q150
is turned on.
Q151
DTC114YK or UN2214 or When POWER IC RESET is activated, a base becomes Hi,
KRC107S
SVR discharge SW Q151 is turned on.
Q200
DTC124EK or UN2212 or
KRC103S FM +B SW Q201 is turned on when Q200's base becomes Hi.
Q201 2SB1277(Q,R) Works during FM reception mode.
Q202
DTC124EK or UN2212 or
KRC103S AM +B SW Q203 is turned on when Q202's base becomes Hi.
Q203 2SB1277(Q,R) Works during AM reception mode.

KRC-20SA/G
4
COMPONENTS DESCRIPTION
Ref.No.
Component Name Application/Function Operation/Condition/Compatibility
Q260
DTC114YK or UN2214 or
KRC107S Motor +B SW When Q260's base becomes Hi, Q261 is turned on.
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 or
KRA103S
P-CON. protection inhibit SW Inhibits protection SW function when P-CON works momentary.
Q353
DTC114YK or UN2214 or Q353 is turned on when a base becomes Hi.
KRC107S
P-CON. SW Works during POWER ON mode.
Q370 2SB1277(Q,R) Q370 is turned on when Q371's base becomes Hi.
Q371
DTC114YK or UN2214 or ANT-CON. SW Works during TUNER mode.
KRC107S

KRC-20SA/G
5
MICROCOMPUTER'S TERMINAL DESCRIPTION
● Terminal Description (IC1 : X14-6852-71)
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
CANCELLER I Noise canceller input Pull down to GND lines. (Not used)
50 SEL1 I Destination input 1 Hi : KRC-20S
51 SEL2 I Destination input 2 Hi : KRC-20S
52 SEL3 O Destination input 3 N.C. (Not used)