Kenwood KR-C2904 Service Manual

©

2002-10 PRINTED IN JAPAN

B51-7981-00 (N)2139

CASSETTE RECEIVER

KRC-17G/YA/YG KRC-194A/G/YA/YG KRC-266LA/LG/RG KRC-27YA/YG KRC-2904YA/YG KRC-294A/G/YA/YG

SERVICE MANUAL

KRC-266RG

KRC-17G/YA/YG, KRC-194A/G/YA/YG (E)

KRC-2904YA/YG (E)

KRC-266RG (M)

Escutcheon (B07-2188-02)

45W x 4

KRC-266L

45W x 4

AUTO

AME

KRC-294

45W x 4

KRC-27

45W x 4

KRC-2904

45W x 4

T.CALL

KRC-17 KRC-194

45W x 4

T.CALL

KRC-27YA/YG (E)

KRC-294A/G/YA/YG (E)

KRC-266LA/LG (M)

Mounting hardware assy (J21-9701-03)

Plastic cabinet assy (A02-1486-13)

Screw set (N99-1610-15)

Lever (D10-3031-04)

x2

Antenna adaptor (T90-0523-05)or (T90-0534-05)

WIDE BAND

DC cord (E30-4790-05)or (E30-6134-05)

Screw set (N99-1719-05)

AUTO

AME

Panel assy (A64-2924-02):KRC-194A/G/YA/YG (A64-2925-02):KRC-17G/YA/YG

Panel assy (A64-2927-02)

Panel assy (A64-2933-02)

Panel assy (A64-2923-02)

Panel assy (A64-2917-02)

Panel assy (A64-2916-02)

Depends on model. Refer to the parts list

KRC-17G /YA/YG, 194A/G/YA/YG, 266LA/LG/RG

KRC-27YA /YG, 2904YA/YG, 294A/G/YA/YG

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

NC,MPX

E-VOL.

CD/MD CHANGER

FRONT Lch

FRONT Rch

REAR Lch

REAR Rch

J2

LCD DRIVER

LCD

CME1

MAIN

TAPE MECHA.

IC5

Lch

Rch

PRE OUT

IC2

IC4

IC3

SP OUT

REAR

J4

PAN IN SW

ACC DET.

P-CONT.

J2

J5

IC1

F/E

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

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

L CLK

L DATA S

L DATA L

FWD/REV

MOTOR

CH CON

DATA H

DATA C

REQ H

REQ C

CH CLK

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.

CH RST

S MUTE

8

5

10

B.U.5V

AM+B

VDD 5V

PACK IN

L RES

PHONE

CH

MUTE

BEEP

SVR

AMP. STBY

SVR

AC GND (BEEP)

Lch Lch

Rch

Lch

1200mV

TAPE :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

CM1

PLAY HEAD

L/R

55.6mV

B.U.5V

SW 5V

8V

B.U.5V

AM: 170mV

FM: 213mV

TAPE

PACK IN

(FF/REW)

AMP. MUTE

FF/REW

B.U.5V

R QUAL IF COUNT

R CLK

R DATA

SW 5V

MP OUT

QUAL

AFC

NOISE

B.U.5V

ILL

L CE

(X16)

A1

TEL DET

D380

5V

R205

M

KRC-17G /YA/YG, 194A/G/YA/YG, 266LA/LG/RG

KRC-27YA /YG, 2904YA/YG, 294A/G/YA/YG

3

● SYNTHESIZER UNIT (X14-687x-xx)

COMPONENTS DESCRIPTION

Ref.No.

Application/Function Operation/Condition/Compatibility

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.

KRC-17G /YA/YG, 194A/G/YA/YG, 266LA/LG/RG KRC-27YA /YG, 2904YA/YG, 294A/G/YA/YG

4

● SYSTEM MICROCOMPUTER UPD780058GC (IC1 : X14)

Pin No.

Pin 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 LILCD driver communication data.

-

12

L DATA SOLCD 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 F

ront-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.

-

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. -

Pin No.

Pin Name

I/O Function

Operating Condition

46 REQ H O Changer request. 47 - - - 48 SVR O SVR control. 49

AMP STBYOPower 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/REVICassette 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-REQIKey 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 CONTOA/D converter reference voltage.

-

80 - - - -

MICROCOMPUTER'S TERMINAL DESCRIPTION

KRC-17G /YA/YG, 194A/G/YA/YG, 266LA/LG/RG

KRC-27YA /YG, 2904YA/YG, 294A/G/YA/YG

5

ADJUSTMENT

(2-LINE TAPE)

B

A

B

A

(FWD)

(RVS)

HEIGHT

(FWD)

HEIGHT/AZIMUTH

(FWD)

HEIGHT/AZIMUTH

(RVS)

TAPE SPEED

HEIGHT

(RVS)

F

''

F

R

No ITEM

INPUT SETTINGS

RECEIVER SETTINGS

ALIGNMENT

POINTS

ALIGN FOR

SD

HEAD

HEIGHT

HEAD

AZIMUTH

TEST MODE : ON While holding the "FM" key and preset "6" key, reset the unit. TEST MODE : OFF Reset the unit.

98.1MHz 0 dev

35dBµ(ANT input)

990 kHz 0% mod

35dBµ(ANT input)

SCC-1659

TCC-153

10kHz

TEST MODE: ON

FM

98.1MHz

TEST MODE: ON

AM

990 kHz

TAPE PLAY

Connect an AC

voltmeter and

oscilloscope to

SP outputs.

TAPE PLAY

Preset "1" key,

and

preset "6" key

Preset "1" key,

and

preset "6" key

Head Height Screw

Head

Azimuth

Screw

While holding preset "1" key, press and hold preset "6" key for a few seconds.

"ADJ OK" is good. "ADJ NG" is not good.

While holding preset "1" key, press and hold preset "6" key for a few seconds.

"ADJ OK" is good. "ADJ NG" is not good.

1) During FWD transport adjust

F and F ' so that line A of 2-

LINE TAPE passes through the center of the head shield plate (core center area)

2) During RVS transport adjust

R and R' so that line B of 2-

LINE TAPE passes through the center of the head shield plate (core center area)

3) After the alignment above, reverse the transport direction and check the FWD alignment again. If it is deviated, perform alignment again. (Tape used : SCC-1659,manufactured by A-BEX)

Adjust the azimuth for each L ch/R ch or FWD/RVS becomes maximum.

1

(1)

[1]

[2]

FM SECTION

AM SECTION

CASSETTE DECK SECTION

A B C D E

1

2

3

4

5

6

7

6

4.3320MHz

W24

W64

W76

W78

R200

R202

W36

R55

W73

W69

W12

W99

R67

W58

W104

C4

R350

R370

W67

W57

W70

C209

L10

W66

W68

W4 W6

W72

W71

W7

W85

W80

W39

W42 W45 W48

W50

W101

W102

W2

W200

R51

R65

R351

R353

R66

X1

C50

C17

C18

C160

C152

C55

W15

C15

C16

C161

C350

C352

C503

C162

C500

C450

C451

C150

C159

C56

C58

C53

C57

W97

W98

W103

W53

W43

W51

W28

W10

X2

W17

R501

W3

R502 R500

R261

L5

R260

L4

C402

C400

C401

W54

W47

W95

W93

W89

R119

W13

W61

W62

W14

C9

C250

C10

W8

W9

W33

W23 W27

W30 W32

W37

W26

W55

W56

R263

R262

W22

W77

W63

W65

W21

R252

W105

W52

W100

W94

W96

W92

W91

W90

W87

W59

W60

W20 W25

W29 W31 W35

W19

W11

W82

W79

W83

W40

W38

W41

W84

W81

C3

W34

W18

W49

W46

W44

R120

W88

W74

W75

4.19MHz

TP

5V

DG

S-MTR

PDA

PCK

2DA

CCK

DTH

DTC

CMP

2CK

L1

RES

L8

L7

R100

L12

L6

L3

W5

R107

1

6

8

1

5

8

16

1

9

1

2

25

24

1576109

2 3 4 8 12 11 13

LR

1

24

BEBE

EB

BE

1

11

2

12

BE BE

A1

Q60

Q56

D370

D410

D50

D405

D371

D352

Q51

Q350

D380

D401

D400

D56

D52

D51

D55

D54

D408

D409

D350

D351

D53

Q261

Q201

Q203

D404

D200

D260

P1

IC5

D261

J1

J5

J4

J2

J3

IC4

D150

D152

D151

WH1

D100

CN1

W170

C251

R156

R15

W158

R14

R62

W159

R57

R59

W157

R60

C52

C163

R161

R159

R162

R16

R13

W174

R381

C380

R61

R251

R151

C214

R503

C600

C601

W171

R125

R123

C13

C14

R58

R52

R54

R106

R112

C164

R352

C154 C153

C351

TH1

R504

R155

R154

R153

R322

R401

R400

R380

R408

R409

R407

R406

R412

R410

R411

R303

R302

R304

R306

R305

R403

R301

R402

C504

C54

C502

C505

R63 R64

W162

C501

R1

C1

R201

R203

R150

W153

C452

C202

C204

R455

R453

R454

R451

R450

R452

R205

R141

R2

C2

C5

R382

C6

C157

R111

R113

R404

R103

R108

C151

C156

C155

R160

R206

R207

C158 C506

R8

C8

R4

R6

R7

C7

R5

R133

R323

R110

R158

C101

C102

R105

C103

W161

W160

R48

R320

R321

R140

W173

W154

R124

R122

R118

R152

R121

R117

R157

R405

R143

R104

W169

W168

W167

R3

R250

W165

R49

R413

W156

R142

W166

W164

R101

R102

C104

W163

114

1528

814

71

41

13

45

60

1

20

80

61

21

40

18

16 9

BE

BEBE

BE

Q61

IC1

Q52

Q59

Q58 Q57

Q153

Q151

Q150

Q55

Q49

Q54

Q53

Q50

Q500

Q502

Q501

Q353

Q301

Q320

Q352

Q351

IC6

IC7

Q451

Q450

Q260

IC3

IC2

Q503

Refer to the schematic diagram for the values of resistors and capacitors.

PC BOARD

(FOIL SIDE VIEW)

SYNTHESIZER UNIT X14-687x-xx (J74-1319-02)

Ref. No address Ref. No address Ref. No address Ref. No address Ref. No address Ref. No address

IC1 4D IC2 3C IC3 4C IC4 4B IC5 6D IC6 5D IC7 2E

Q49 5C Q50 5C Q51 5C Q52 5C Q53 6C Q54 5C Q55 5B

Q56 6B Q57 6B Q58 6C Q59 6C Q60 6B Q61 6C

Q150 4C

Q151 4B Q153 2C Q201 2C Q203 2C Q260 3E Q261 3E Q301 4D

Q320 5E Q350 4B Q351 4C Q352 4C Q353 5C Q450 2B Q451 2B

Q500 2D Q501 3D Q502 3D Q503 3D

X14-687x-xx

F G H I J

1

2

3

4

5

6

7

PL1 PL2

FM

AM

AUD

RST654321AT T

VOL

SRC

TI

1 54

CLK

D15

D1

D2

D3

D4

D5

D6

D7

D8

D9

D10

D11

D12

D13

D14

X16-1512-7x (J74-1300-02)

SWITCH UNIT SWITCH UNIT

X16-1512-7x (J74-1300-02)

C5

C2

C3

C4

R2

R3

R4

R5

R6

R7

R8

R9

R21

R10

R11

R12R13

R14

R15

R17 R18

C1

1

2441

64

65 80

40 25

11

12

2

1

BE

Q1

IC1

D17

J1

PC BOARD

(COMPONENT SIDE VIEW) (FOIL SIDE VIEW)

Refer to the schematic diagram for the values of resistors and capacitors.

Ref. No address

IC1 3I

Q1 4I

X16-1512-7x

A B C D E

1

2

3

4

5

6

7

13

4

3

128

711

21610

59

16 15 14 13 12 11 10

876543 2

FL+

RL+

FL-

RL-

FR-

RR-

FR+

RR+

P-ANT

P-CON

ACC

19

23

17

21

9

375

R412 100

R410 4.7K R409 4.7K

R402 10

R411 100

R406 4.7K

R407 4.7K

R408 1K

R403 100

7

6

5

46

45

1

17

63

16

10

0.47u50

C401

+

R401

C402 0.47u50

+

R400 4.7

C400 22u6.3

+

100K

R413

100K

0.01

3.3K 1/2W

R370 4.7K

R350 4.7K

R351 1K

R352

3.3u25

C350

+

22K

C351

0.1u50

C352

+

1K

0.068

55

1K

R67

18

1

61 62 63

64 65

66 67 68 69

70

71 72 73 74 75 76 77 78 79 80

PANEL

SEL 1 R CLK

PACK IN

VDD 1 X2

X1 IC

XT1 VDD 0

S METER

2

A GND

REQ C DATA C

8B.U.3

CON

MUTE45910

DGND

REQ H

1 2

9

6 7

CLKRch 13

10 6

RST1112

75

DATA H

Lch

13 11 12 8 4 312

1/2W

REQ C

KEY-REQ

SEL 0 VSS 0

AVREFO

PHONE NOISE AV CONT

∗

R107

R106

2.2K

10K

62

47K

R105

6.8K

X1

C102

15P 15P

C103

10

R100

0.022

C104

R55 47K

K

R57

C52

54

R353

Q351

T-MUTE

R380

10K

0

C

2

R

∗

R104 47K

∗

R103 47K

∗

R101 47K

∗

R102

57

53

58

60

63

RL-

BU

YEL

9

TEL MUTE

BRN

12 11 10

VIOL/BLK

GRN/BLK

RR+

RR-

RL-

VIOL

15

13

14

RL+

GRN

16

13 57

RR+

RL+

FL+

FL-

FR-

RR-

FR+

2

68

57

4

13

68

GND

4

ACC

P-CON

B

A

BLK

1

ANT. CON

P. CON

BLU/WHT

RED

4

2

3

GRY/BLK

WHT/BLK

GRY

7 6 5

FRFR+

FL-

WHT

8FL+

R261

R262 47K

GND 1

PACK IN

2

1/2W

1K

R260

10K

R263 47K

GND 5

MOT

3

MOT

4

T.MUTE 6 28

27

+B

GND

Q58,59

Q60,61

Q350,353

Q352

76

78

R405

R404

R382 47K

R51

4.19MHz

47K

∗

R108

1

2 34

5

C101

0.01

+B

+B+B

+B

+B+B

+B+B+B

+5V

+5V+5V+5V

IC6

(E30-4790-05)

DC1

47K

22K

47K

10K

47K

22K

10K

47K

J4

J2

D400

D401

D408

D405

D410

D409

D404

D261

D5

D351

D370

ANT-CON.

Q350

Q351

D352

Q353

Q352

Q301

Q58

Q60

Q61

Q59

D56

∗

A

TOP VIEWJ4

D371

ILLUMI +B SW

ILLUMI +B DRIVER

DRIVER SW

P.CON PROTECTION SW

Q49

P-CON.

P.CON

DETECTION

ACC

D3

D100

MOTOR +B SW

Q260

MOTOR+B DRIVER

D260

WH1

Q261

RESET

CD-CH SW

P.CON PROTECTION INHIBIT SW

SW

0.9V

0V or 5.0V

0V

0V o

0V

5.0V

0V

5.0V

1V

0V

5.0V

0V

5.0V

2SB1565

DTA114E DTA124EK DTA144EK DTC114TK DTC114YK DTC124EK DTC143TK DTC144EK KRC103S 2SA1036K 2SC2412K

2SB1548

2SB1277 2SB1443

2SA1037K

KRA102S KRC104S

LA3161

TDA7479D

CAUTION : For continued safety, replace safety critical components only with manufacturer's recommended parts (refer to parts list).

Indicates safety critical components. To reduce the risk of electric shock, leakage-current or resistance measurements shall be

carried out (exposed parts are acceptably insulated from the supply circuit) before the appliance is returned to the customer.

• DC voltages are as measured with a high impedance voltmeter. Values may vary slightly due to variations between individual

instruments or/and units.

!