KENWOOD KRC-31Y, KRC-36, KRC-366L, KRC-37, KRC-37Y SERVICE MANUAL

CASSETTE RECEIVER

KRC-31Y/36/366L/37/37Y

/391/394/394Y/466R
/4904Y

SERVICE MANUAL

Mechanism extension cord : W05-0477-00 (7P), W05-0609-00 (10P)

© 2002-10 PRINTED IN JAPAN
B51-7986-00 (N) 2139

KRC-36/37/37Y
/391/394
/394Y/466R

KRC-31Y/366L

KRC-4904Y

SRC

SRC

SRC

Panel assy
KRC-391:
(A64-2538-02)

KRC-XXXX

OFF

LOUD SCRL SCAN REP T.CALL M.RDMB.S/RDM MENU TI VOL ADJCLK

45Wx4

DISC

AUD

KRC-36:
(A64-2541-02)
KRC-466R:
(A64-2941-02)
KRC-394/394Y:
(A64-2945-02)
KRC-37/37Y:
(A64-2947-02)

Panel assy

KRC-XXXX

OFF

OFF

LOUD SCRL SCAN REP T.CALL M.RDMB.S/RDM MENU AUTO AMECLK

KRC-4904

LOUD SCRL SCAN REP T.CALL M.RDMB.S/RDM MENU AUTO AMECLK

45Wx4

DISC

AUD

WIDE BAND

45Wx4

DISC

AUD

KRC-366L:
(A64-2942-02)
KRC-31Y:
(A64-2946-02)

Panel assy
(A64-2948-02)

DC cord
(E30-4792-05)

Screw set
(N99-1610-15)

Plastic cabinet assy
(A02-1486-13)

Screw set
(N99-1719-05)

Depends on model. Refer to the parts list.

Mounting hardware assy
(J21-9716-03)

Antenna adaptor
(T90-0523-05)

Escutcheon
(B07-)

Lever
(D10-4589-04)

x2

KRC-31Y/36/366L/37/Y

FM ANT
AM ANT

RF GND

FM+B

AM+B
AM LO/DX
FM LO/DX

IF SELECT

RDS OUT

FM SD OUT

REQUEST

K2I-VTH

VCO-GND

FSD OUT
FM DET OUT
AM DET OUT

IF GND

COMMON+B

P-ON 5V

DIG GND

PLL DATA

PLL CLK

PLL CE

HI UP ADJ

FM+B
AM+B

A8V

SW5V

LO/DX

SD
S-METER

PLL-DATA

PLL-CE

SW5V

ACC-DET

BU-DET

SCL

MUTE

SDA

EN1
EN2
EN3

PANEL

RESET

DSI

CH MUTE

NOISE

DATA H

DATA C

REQ H

REQ C

CH RST

CH CON

CH CLK

Rch

COM

Lch

TAPE L/R

MP IN
AFS
QUAL

AM

MPX

OUT RR

OUT LR

OUT RF

LEVEL

SCL

SW5V

SDA

SCL

SDA

OUT LF

STBY
MUTE

SMUTE

5

10

BU5V

AFS

R QUAL

R CLK

R DATA

BU5V

REMO

SW5V

GREEN

RED

BU5V

PHONE

BEEP

SVR

P-MUTE

P-STBY

SVR

AC GND(BEEP)

TAPE L/R

PLL-CLK

SW5V

L-RES

L-CLK

L- DATA S

L- DATA L

MUSIC

EQ-MUTE

MS-CONT

MUSIC
EQ-MUTE
MS-CONT

FWD/REV

PACK IN

M-STBY

T-MODE

T-END

L-CE

340mV

SUB+
SUB-

Rch

Lch

PACK

T-END

M-STBY

T-MODE

FWD

REV

AUDIO

8V

MOTOR

BU14V

SW5V

IN

PLAY HEAD

SW5V

BU14V

BU5V

BU14V

EN1
EN2
EN3

P,CON

ILLUM
B.U.5V

AM+B
AUDIO

FM+BFM+B

AM+B

AUDIO 8V

AUDIO 8V

AUDIO 8V

BU5V

SW5V

TAPE
CD-CH

AM

FM

: 1719mV
: 3424mV

: 550mV

: 1727mV

TAPE
CD-CH

AM

FM

: 1786mV
: 3546mV

: 850mV

: 1345mV

AM : 160mV

FM : 213mV

CD L/R

1200mV

BU14V

CD L/R

8

RDS

ANT.

DECODER

SYSTEM u-COM

KEY

PAN 5V

MUTE

E2PROM

EQ AMP

CD ISO AMP

E-VOL

LCD DRIVER

LCD

DSI

REMO

RST SWPAN IN SW

GREEN

RED or

RST IC

TEL DET TEL MUTE

DRIVER

MAIN

SUB

AVR

SW5

B.U. DET

SURGE-DET

B.U.

ACC

P-CONT

DC CONNECTOR

REGULATOR

ACC DET

J2

VOLTAGE

MUTE

PRE

R-Lch

R-Rch

AMP

SVR

MUTE

THERMO
PROTECTION

FRONT Lch

FRONT Rch

REAR Lch

REAR Rch

IC4

J4

POWER IC

TDA7386

CD/MD
CHANGER

SP OUT

J5
PRE OUT

IC10

SUB MOTOR
DRIVER

MOTOR

DRIVER

IC1

IC2

IC12

IC9

IC2

IC1

IC11

IC7

IC8

Q2,3

IC6

TUNER

(X16)

(X14)

MM

TAPE MECHA

2

/391/394/Y/466R/4904Y

BLOCK DIAGRAM

KRC-31Y/36/366L/37/Y

/391/394/Y/466R/4904Y

COMPONENTS DESCRIPTION

● SYNTHESIZER UNIT (X14-689x-xx)

Ref. No. Function Operation

IC1 System µ-com
IC2 E-volume
IC4 Power amplifier Speaker output.
IC6 RDS decoder
IC7 Power IC
IC8 Mute control logic 3 input NOR gate x 3.
IC9 Equalizer amplifier For full logical cassette mechanism control.
IC10 Sub motor driver For full logical cassette mechanism sub motor driver.
IC11 Reset IC Detection voltage below 3.0V.
IC12 EEPROM
Q1 P. CON detection Detects P.CON voltage.
Q10 Backup detection Detects the backup voltage.
Q11 Surge detection Detects surge voltage.
Q20 ACC detection Detects ACC voltage.
Q40 Preout mute driver Mutes when the base terminal voltage level becomes “L”.
Q50 5V SW Works when the base terminal voltage level becomes “L”.
Q101 DSI SW LED for DSI works when the base terminal voltage level becomes “H”.
Q151 Panel 5V SW Works when the base terminal voltage level becomes “L”. Supplies VDD to panel.
Q201 Noise detection Detects noise.
Q221~224 Preout mute Mutes when the base terminal voltage level becomes “H”.
Q251 Power IC SVR SW Discharges the capacitor’s voltage of SVR terminal after the base terminal voltage becomes “H”.
Q301 Local seek SW Changes to the local seeking after the base terminal voltage becomes “H”.
Q501 Motor driver AVR Works when the base terminal voltage becomes “H”. Supplies the power to the motor driv er.
Q551 Main motor SW Works when the base ter minal v oltage becomes “L”.
Q552 Main motor SW Works when the base ter minal v oltage becomes “H”.

● SWITCH UNIT (X16-1532-7x)

Ref. No. Function Operation

IC1 LCD driver
IC2 Remote sensor
Q1 Key scan SW Receives key signal when the base terminal voltage becomes “L”.
Q2 Key illumination SW Key illumination color becomes green when the base terminal voltage becomes “H”.
Q3 Key illumination SW Key illumination color becomes red when the base terminal voltage becomes “H”.

3

KRC-31Y/36/366L/37/Y
/391/394/Y/466R/4904Y

MICROCOMPUTER’S TERMINAL DESCRIPTION

● Microcomputer : UPD780058GCxxx (X14 : IC1)

Pin No. Pin Name I/O Function / Operating Condition

1 DSI O DSI control.
2 PANEL I Panel detection. “L” : Panel exists
3- -­4 AVSS - GND.
5 L-RST O LCD driver reset.
6 L-CE O LCD dr iver chip enable.
7 AVREF1 I Reference voltage.
8- -­9 PLL-DATA I/O Front-end communication data.
10 PLL-CLK O Front-end communication clock.
11 L-DATA L I LCD dr iver communication data.
12 L-DATA S O LCD driver communication data.
13 L-CLK O LCD driver communication clock.
14 R-DATA I RDS data.
15 R-QUAL I RDS QUAL.
16 CH-DATA C I Changer communication data.
17 CH-DATA H O Changer communication data.
18 CH-CLK I/O Changer communication clock.

19 M-STBY I

20 T-END I
21 ACC-DET I ACC detection.
22 BU-DET I Backup detection.
23 IC2 TYPE 0 I For service. “L” : Normally
24 IC2 TYPE 1 I For service. “L” : Normally
25 TYPE 0 I Destination discrimination.
26 TYPE 1 I Destination discrimination.

27 TYPE REF O

28 MOTOR O

29 PLL-CE O

30 SD I

31 ASF O
32 LO/DX O
33 VSS1 - GND.
34 P-MUTE O Power amplifier muting.
35 SVR O SVR control.
36 - - ­37 IC2-SCL O E-volume communication clock.
38 IC2-SDA I/O E-volume communication data.
39 MUTE O Muting control.
40 P-STBY O Power amplifier standby.

4

Cassette tape standby detection.
“H” : Standby
Tape end detection. “H” : Run, “L” : Stop

Reference voltage for destination
and service.
Cassette mechanism motor.
“H” : ON, “L” : OFF
Front-end communication ship enable.
Station detection. “H” : Station exists,
“L” : Station does not exist
Noise detection time constant switch.
Local seeking switch. “H” : LO, “L” : DX

Pin No. Pin Name I/O Function / Operating Condition

41 P. CON-DET I P. CON short-circuited detection.
42 CH-CONT O Changer control.
43 - - ­44 CH-REC H O Changer request.
45~47 - - ­48 EN2-1 O Power supply IC control.
49 EN2-0 O Power supply IC control.
50 BEEP O Buzzer.
51 EN3 O Power supply IC control.
52 EN1 O Power supply IC control.
53 SW 5V O P. ON 5V control. “H” : OFF, “L” : ON

54 MUSIC I

55 MS-CONT O

56 EQ-MUTE O

57 FWD/REV I

58 SUB+ O Sub motor control.
59 SUB- O Sub motor control.
60 RESET I System reset.
61 REMOTE I Remote control.
62 R-CLK I RDS clock.
63 CH-REQ C I Changer request.
64 PACK-IN I Cassette tape pack-in detection.
65 KEY-REQ I Key signal detection.
66 - - ­67 VSS0 - GND.
68 VDD1 - VDD.
69 X2 - Main system clock.
70 X1 I Main system clock.
71 IC - ­72 - - ­73 XT1 - VDD.
74 VDD0 - VDD.
75 AVREF 0 I Reference voltage.

76 S-METER I

77 T-MODE I Cassette tape mode detection.

78 PHONE I

79 NOISE I Noise detection during FM mode.
80 AV CONT O reference voltage.

Tape signal detection. “H” : Signal
does not exist, “L” : Signal exists
tape advanced sensitivity control.
“H” : Play, “L” : FF/REW
Cassette tape muting. “H” : ON, “L” : OFF
Cassette tape runing direction detection.
“H” : FWD, “L” : REV

SD detection.
“H” : SD exists, “L” : SD does not exist

Navi mute : Over 2.5V,
Tel mute : Less tha 2.5V

KRC-31Y/36/366L/37/Y

/391/394/Y/466R/4904Y

ADJUSTMENT

BALANCE/FADER/BASS/TREBLE : CENTER
T. ADV/METAL/DOLBY NR/AUTO : OFF

No. Item Input Output Receiver Alignment Align For Fig.

Settings Settings Settings Points

FM Section

While holding preset “1” key,
press and hold preset “6” key

1SD

AM Section

(1) SD

Cassette Deck Section

1 AZIMUTH

98.1MHz
0 dev

35dBµ

(ANT input) (7 seg model :

990kHz

0% mod

35dBµ

(ANT input) (7 seg model :

TCC-153 Head azimuth screw

10kHz

– FM

– AM

SP OUT TAPE PLAY

TEST MODE : ON

98.1MHz

TEST MODE : ON

990kHz

Preset “1” key, and “ADJ OK” is good.

preset “6” key “ADJ NG” is not good.

Preset “1” key, and “ADJ OK” is good.

preset “6” key “ADJ NG” is not good.

(FWD/REV)

for a few seconds.

“1111” is good.
“0000” is not good.)

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

“1111” is good.
“0000” is not good.)

Adjust so that output level in

playing “FWD” and “REV” (a)
becomes maximum each.

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

(a) AZIMUTH

FWD

REV

PANEL FRONT

5

A B C D E

0

5

A

M

SYNTHESIZER UNIT (X14-689X-XX)

CLK

REQ C

R411 100

R408 4.7K

C404 0.01

R415 100K

7

5

6

R413 100K
R414 100K
R412 100K

63

18

17

+B

39

5V
0V

5V
0V

0V

IC8

1

2

3
4

5

6
7

GND

MUTE
DRIVE

PREOUT
MUTE DRIVER

VDD

14
13

12
11
10
9

8

IC1 :

1

IC2 : TDA7407D
IC4 :
IC6 : TDA7479D
IC7 : TDA3682ST
IC8 : HD74HC27FP
IC9 : HA12221F
IC10
IC11
IC12

Q1,301 : DTC124EUA or
Q10,11,20,101,201

Q40 : DTA124EUA or
Q50 : 2SA1036K

Q151 DTA114YUA or:

2

Q223,224 : DTC143TUA or
Q251 : DTC114YUA or
Q501 : 2SD1760

Q551 : 2SB1443
Q552 : DTC114EUA or

D1 :
D2,3 : 1GWJ43 (TPB5)

D4,551 : AM01Z or
D10,11,401,402
D20 : MA4051 (N) -M

3

D40,101,251-253
D102

D153,154,157,159-161,

∗

TDA7386

LB1930M

:

S-80835CNNB

:
: BR24C01AF

UN5212
2SC4081 or:

2SD1819A
UN5112

UN5114
UN5216
UN5214

UN5211
1N5393G-M6 or

S2V20 A

ERA15-01

: MA4068 (N) -M

MA4047-M or:D30
HZS5B1

: 1SS133
: B30-1567-05

403,404,407,409-411

MA4062-L or:
HZS6C1

ACC

RED

BLK

8

A-PART

75

B-PART

7B531

GRN

GRN/BLK

REAR. L

(E30-4792-05)

BATT

P.CONT OUT

ANT.CONT

BLU/WHT

WHT/BLK

FRONT. L

YEL

31

GRY

GRY/BLK

FRONT. R

64

6248

WHT

DC1

2

VIOL

A

VIOL/BLK

REAR. R

CH-IN

B.U.

+B

+B

D404
D407
D401
D402
D403
D409
D410
D411

GND

CON

REQ H

R404 100

R405 4.7K

44

J4

159

2

43812

MUTE

S GND

R403 4.7

R406 4.7K

+

C403 100u10

42

10

13

7611

Lch

Rch

RST

DATA H

DATA C

R402 10

C402 1u50+C401 1u50

R407 4.7K

R409 4.7K

16

R401 10

+

R410 100

SIGNAL LINE
GND LINE

B LINE

A1

CB

YES

X86-3512-70

NO

X86-3512-72

NO

X86-3512-70

NO

X86-3512-70
X86-3512-70

CASSETTE MECHANISM
(D40-1150-05)

YES

UPD780058GC418

NO

UPD780058GC426
UPD780058GC418

NO

UPD780058GC426
UPD780058GC418NONO

PACK

IC1

MODE

R111C308

YES

NO
NOYES

YES

FWD/REV

FWD/REV

R112

NO

YES
YES

R113

YES

YES
YES

NO
NO

4

5

(X14-689X-XX)

MODEL NAME
KRC-394Y (E)

KRC-37Y (E)
KRC-394 (E)
KRC-37 (E)
KRC-36 (E)
KRC-391 (E)
KRC-4904Y (E)
KRC-31Y (E)
KRC-366L (M)
KRC-466R (M)

+B

UNIT

No.

2-70

2-72

2-71
0-22
0-21 YES YES YES

PACK

M1M2

MAIN

HD1

+2V

SUB

M

M

7
6

T-END

5

STBY

4
3
2
1

PLAY

10

HEAD R

9

HEAD COM

8

HEAD L

7

6

GND

F/R

PACK IN

SUB(+)

SUB(-)

MODE+B

MODE

6
5
4
3
2
1

HEAD

Rch

Lch

+2V

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

7

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.

M+R

GND

T-END

STBY

GND

R114

NO

NO

NO
YES
YES

R146R118

YESYES

NO NONO
YESNONO
NO
YES YES

HEAD COM

Q301

YES

YES

NO

YES

MODE

MODE+B

SUB(-)

SUB(+)

PACK IN

GND

HEAD L

HEAD R

GND

STBY

T-END

GND

M+B

CN1

F/R

CN2

1

2
3
4
5
6
7

8

9

10

1
2
3
4

5

6

7

R533 470C532 0.01

R534 100K

R536

22K

R535

9
7

19

R556 470
R554 470

20

D551

Q551

1K

R552

470

R531

R551 10K

1/2W

10K

10K

Q552

MOTOR

+2V

+B +B

SUB MOTOR
DRIVER

IC10

6

0V 0V

PGND

7

7.6V

7

+5V

77

470

64
57

9

+B28

C511

1500P

C512

1500P

R513

C513

150

22u6.3

OUT2

8

NC

C533C534

9

7.6V

OUT1

10

NC

0.22 0.22

330K 5.1K

C516

R516

12K

0.01

+

C514

22u6.3

150

R514

3.8V

C509
1u50

+

0V

3.8V

15K

R511

3.8V

15K

R512

3.8V

+

C515

0.01
R517 R519

330K 5.1K

R515

12K

5

SGND

4

5.0V

IN2
IN1
NC

VCC

R520R518

31

NFI (R)

32

R IN (R)

33

RIP

34

F IN (R)

35
36

37

F IN (L)

38

V REF

39

R IN (L)

40

NFI (L)

58

3

5.0V

59

2
1

7.7V

+B

4.3K

R522

C518

0.1u50

3.8V

3.8V

302928272625242322

D IN (R)

M-OUT (R)

EQ OUT (R)

3.8V

EQUALIZER
AMPLIFIER

M-OUT (L)

RQ OUT (L)

D IN (L)

1

2

345

3.8V

3.8V

+

C517 0.1u50

4.3K

R521

+

IC9

3.8V

+B

3.8V

3.8V

RAI (R)

RAI (L)

PB OUT (L)

678

3.8V

PB OUT (R)

MS GV (R)

5V

S/R (MSGV)

0V

9

21

MA OUT

MS DET

5V
1V

MUSIC

MUTE

10

MS GV (S)

MSI

VCC

F/R

MTL