Kenwood KRC-4902Y Service Manual

2002-1 PRINTED IN JAPAN

B51-7880-00 (N)1089

CASSETTE RECEIVER

KRC-4902Y

SERVICE MANUAL

Mounting hardware assy (J21-9641-13)

Antenna adaptor (T90-0523-05)

Lever (D10-4589-04)

DC cord (E30-4792-05)

Plastic cabinet assy (A02-1486-13)

LOUD SCRL SCAN REP M.RDMT.CALLB.S/RDM MENU AMEAUTOCLK

KRC-4902

SRC

OFF

45Wx4

WIDE BAND

DISC

AUD

Front glass

(B10-4129-01)

Knob(1-6) (K25-1392-03)

Knob(SRC) (K24-3820-04)

Knob(FM,AM) (K25-1393-03)

Knob(VOL) (K25-1395-03)

Cassette lid (A53-1687-03)

Panel assy

(A64-2540-02)

Knob(AUD) (K24-3821-04)

MECHANISM EXTENSION CORD

W05-0477-00 (7P)

W05-0609-00 (10P)

KRC-4902Y

BLOCK DIAGRAM

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

MPX

OUT RR

OUT LR

OUT RF

LEVEL

SCL

SW5V

SDA

SCL

SDA

OUT LF

STBY MUTE

SMUTE

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

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

MOTOR

BU14V

SW5V

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

BU5V

SW5V

TAPE CD-CH

: 1719mV : 3424mV

: 550mV

: 1727mV

TAPE CD-CH

: 1786mV : 3546mV

: 850mV

: 1345mV

AM : 160mV

FM : 213mV

CD L/R

1200mV

BU14V

CD L/R

ANT.

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

VOLTAGE

MUTE

PRE

R-Lch

R-Rch

AMP

SVR

MUTE

THERMO PROTECTION

FRONT Lch

FRONT Rch

REAR Lch

REAR Rch

IC4

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

TUNER

(X16)

(X14)

TAPE MECHA

KRC-4902Y

● SYNTHESIZER UNIT (X14-6892-72)

COMPONENTS DESCRIPTION

Ref.No. Function Operation

IC1 SYSTEM µ-COM IC2 E-VOLUME IC4 POWER AMPLIFIER Speaker output 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 BACK-UP DETECTION Detects the back-up voltage. Q11 SERGE DETECTION Detects serge 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.

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 driver. Q551 MAIN MOTOR SW Works when the base terminal voltage becomes "L". Q552 MAIN MOTOR SW Works when the base terminal voltage becomes "H".

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".

● SWITCH UNIT (X16-1532-71)

Ref.No. Function Operation

KRC-4902Y

● µ-COM (IC1 : X14-)

Pin No.

Pin name I/O Description

Processing Operation

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 driver 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 driver 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 Cassette tape stand-by detection. "H": Stand-by. 20 T-END I Tape end detection. "H": Run. "L": Stop. 21 ACC-DET I ACC detection. 22 BU-DET I Back-up 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

Reference voltage for destination and service. 28 MOTOR O Cassette mechanism motor. "H": ON. "L": OFF. 29 PLL-CE O Front-end communication chip enable. 30 SD I Station detection. "H": Station exists. "L": Station does not exist. 31 ASF O Noise detection time constant switch. 32 LO/DX O Local seeking switch. "H": LO. "L": DX. 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 stand-by. 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.

MICROCOMPUTER'S TERMINAL DESCRIPTION

KRC-4902Y

Pin No.

Pin name I/O Description

Processing Operation

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 Tape signal detection. "H": Signal does not exist. "L": Signal exist. 55 MS-CONT O Tape advanced sensitivity control. "H": Play. "L": FF/REW. 56 EQ-MUTE O Cassette tape muting. "H": ON. "L": OFF. 57 FWD/REV I Cassette tape running direction detection. "H": FWD "L": REV. 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 SD detection. "H": SD exists. "L": SD does not exist. 77 T-MODE I Cassette tape mode detection. 78 PHONE I

Navi mute: Over 2.5V. Tel mute: less than 2.5V. 79 NOISE I Noise detection during FM mode. 80 AV CONT O Reference voltage.

MICROCOMPUTER'S TERMINAL DESCRIPTION

FIG.

KRC-4902Y

TEST MODE / ADJUSTMENT

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 should not released in conditions of ACC OFF, power OFF, momentary power down or the panel off.

3. Test mode

• Blanking Skip (B.S) OFF.

• Eject a tape by pressing "ATT" key.

4. Audio adjustment

• Enter the audio mode by pressing the "AUD" key or "OPEN/CLOSE" key on the remote controller.

• Set the volume level to be -10dB. In that case, "30" should be shown on the display.

• Loudness OFF.

• The BASS/MIDDLE/TREBLE and BALANCE/FADER can be adjusted to the full-boost/full-cut and full-front/ full-rear each by pressing the "UP" and "DOWN" keys.

5. Menu mode

• Enter the menu mode by pressing "CLK" key or "DNPP" key on the remote controller.

• Only on models with RDS function, Local Seeking should be first menu.

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

TEST MODE

ADJUSTMENT

ITEM

INPUT

SETTINGS

OUTPUT

SETTINGS

RECIEVER

SETTINGS

ALIGNMENT

POINTS

No.

AZIMUTH

TCC-153

10kHz

SP OUT TAPE PLAY

Head azimuth

screw

(FWD/REV)

(ME1)

ALIGN FOR

Adjust so that output level in

playing "FWD"and "REV"

becomes maximum each.

(b)1

CASSETTE DECK SECTION

(b) AZIMUTH

FWD

REV

PANEL FRONT

+ 13 hidden pages