Kenwood KRC-268A Service Manual

CASSETTE RECEIVER

SERVICE MANUAL

KRC-268A

Plastic cabinet assy (A02-1486-13)

Lever (D10-3031-04) x2

Mounting hardware assy (J21-9491-03)

DC cord (E30-4790-05)

KRC-268

AUD

1

23456

CLK

ATT

SRC

PWR OFF

AME ADJAUTO

T.CALL

LOUD

CRSC

HIGH POWER

40Wx40Wx4

A.ADJ

FM

AM

FF

REW

PR OG

Antenna adaptor (T90-0523-05)

Escutcheon (B07-2188-02)

Liquid crystal (B38-1022-05)

Panel assy (A64-1946-02)

40%

2

IC1

KEY

PANEL 5V SW

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

ME1

MAIN

TAPE MECHA.

IC5

1 Lch

2 Rch

PRE OUT

IC2

IC4

IC3

SP OUT

REAR

J4

RESET SW

PAN IN SW

ANT-CONT.

P-CONT.

J2

J5

IC1

FRONT-END

J1

FM+B

Q201

AM+B

Q203

AM BPF

FM BPF

C154,157,R206

C153,156,R207

Q320

Q450,451

Q370,371

Q50

Q350-353

Q353

P-CON.SW

Q54-57

COM+B

Q58-61

ILLUMI.

B.U.5V

Q51,52

SYSTEM u-COM

S1

S2

S3

P-CONT.

CHANGER

RST SW

Q301

D1-15

PL1,2

ANT.

ANT-CONT.

FM ANT

AM ANT

RF GND

FM+B

AM+B

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

CH CON

DATA H

DATA 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

8V

B.U.

CHRST

S MUTE

8

4

10

B.U.5V

AM+B

VDD 5V

PACK IN

L CE

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

M1

HD1

R

55.6mV

BU5V

SW5V

8V

B.U.5V

AM: 170mV

FM: 400mV

L

PACK IN

(FF/REW)

AMP. MUTE

FF/REW

BU5V

ILL

(X13)

M

A1

KRC-268A

BLOCK DIAGRAM

SYNTHESIZER UNIT (X14-614x-xx)

REF. No.

FUNCTION OPERATION

IC1 SYSTEM µ-COM Controls system. IC2 ELECTRIC VOLUME Controls sound volume. Selects each source. IC3 MUTE Controls each mute output. IC4 POWER IC Amplifies power so that the speaker can drive audio signal. IC5 EQUALIZER AMPLIFIER Equalizer amplifier for cassette tape sound.

Q50 BACK-UP DETECTION Stops when the back-up voltage comes less than 9.2V.

Q51,52 BACK-UP 5V AVR Works when the back-up works.

Q53 P.ON DRIVER Works when the power comes. Q54,55 COM+B SW Works when 5V comes. Q56,57 COM+B AVR Works when Q54 and Q55 work. Q58,59 ILLUMINATION +B SW Works when the base level of Q58 comes "H". Q60,61 ILLUMINATION +B AVR Works when Q58 and Q59 work.

Q150 ELECTRIC VOLUME MUTE SW Works when the base level comes "H". Q151 SVR DISCHARGE SW Works when the base level comes "H". Q153 PRE MUTE DRIVER Works when the base level comes "L". Q200 FM +B SW Works when the base level comes "H" in FM mode. Q201 FM +B DRIVER Works when Q200 works. Q202 AM +B SW Works when the base level comes "H" in AM mode. Q203 AM +B DRIVER Works when Q203 works. Q260 MOTOR +B SW Works when the base level comes "H" in the tape mode. Q261 MOTOR +B DRIVER Works when Q260 works. Q301 CHANGER RESET SW Works when the base level comes "L". Q320 PANEL 5V SW Works when the base level comes "L". Q350 P-CON. DRIVER Works when Q353 works.

Q351,352 P-CON. PROTECTION Works when P-CON output voltage goes down.

Q353 P-CON. SW Works when the base level comes "H". Q370 ANTENNA CONTROL DRIVER Works when Q371 works. Q371 ANTENNA CONTROL SW Works when the base level comes "H" in the tuner mode.

Q450,451 PRE MUTE SW Works when Q153 works.

KRC-268A

COMPONENT DESCRIPTION

3

(X14-) IC1 : µ-COM

PORT No. PORT NAME I/O FUNCTION OPERATING CONDITION

1 XIN I µ-com clock. (4.5MHz) 2 GND -

GND.

-

3

L DATA L I

LCD driver data.

-

4

L DATA S

O

LCD driver data.

-

5

L CLK O

LCD driver clock.

-

6 L CE O

LCD driver chip enable.

-

7

SDA I/O E-volume data.

-

8 PLL DATA I/O Tuner data.

-

9

PLL CLK O Tuner clock.

-

10 SD I Tuner signal detection.

"H" : Tuner signal exists. "L" : Tuner signal does not exist.

11

DATA C I Changer data.

-

12 DATA H

O

Head unit data.

-

13

CH CLK

I/O Changer clock.

-

14 - - No connection.

-

15

MOTOR O Mechanism motor.

-

16

SCL O

E-volume clock.

-

17-24

- - No connection.

-

25 AM+B

O

AM power supply.

-

26

FM+B O FM power supply.

-

27

PACK IN

I Cassette tape pack-in.

"L" : Pack in. "H" : Ejection.

28

FF/REW

I FF/REW signal.

"L" : FF/REW. "H" : Play.

29,30 GND - GND.

-

31

VDD - VDD.

-

32

REQ C

I

Request from changer.

-

33

MUTE O Mute.

-

34 CH CON

O

Changer control.

-

35

REQ H

O Request to head unit.

-

36 SVR O Power IC (IC4) discharge control.

-

37

AMP STBY O Power IC (IC4) stand-by.

-

38

AMP MUTE

O Power IC (IC4) mute.

-

39

P CON O P.CON for external amplifier.

-

40 ANT. CON

O

Power antenna.

-

41 SW5

O

Circumambient circuit power supply control.

-

42

ILL O Illumination.

-

43 - - No connection.

-

44

BEEP O

Buzzer. (2KHz)

-

45-47

- - No connection.

-

48

ROLL OFF

I Destination switch.

-

49

N.CAN

I Destination switch.

-

50

SEL1

I

Destination switch.

-

51

SEL2 I

Destination switch.

-

52

--

No connection.

-

53

EQ MUTE

O Tape equalizer mute.

-

54

FWD/REV

I FWD/REV.

-

55 - - No connection.

-

56

REMO

I

Remote control.

-

57-60

- - No connection.

-

61

ACC DET I ACC detection.

-

62

BU DET

I Back-up detection.

-

63

S METER I Tuner signal meter.

-

64

PANEL

I

Panel on/off.

"L" : Panel on. "H" : Panel off.

65,66

GND - GND.

-

67

HOLD

I Clock stop.

-

68

VDD - VDD.

-

69,70

GND

-

GND.

-

71,72

- - No connection.

-

73

VDD - VDD.

-

74,75

GND - GND.

-

76

VSS

- GND.

-

77,78

- - No connection.

-

79

GND - GND.

-

80

XOUT O

µ-com clock. (4.5MHz)

-

KRC-268A

CIRCUIT DESCRIPTION

4

KRC-268A

TEST MODE

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 is not canceled by ACC OFF, power OFF, momentary power

down or the panel off.

3. Audio adjustment

• Set the volume level to -10dB (which is shown as "30" on the display).

• Loudness OFF.

• The BASS/TREBLE and BALANCE/FADER can be set to the full-boost/full-cut and full-

front/full-rear each by pressing the "Track UP" / "Track DOWN" keys.

• Sound coordination doesn't appear for the feed.

5

(2-LINE TAPE)

B

A

B

A

(FWD)

(RVS)

HEIGHT

(FWD)

HEIGHT/AZIMUTH

(FWD)

HEIGHT/AZIMUTH

(RVS)

TAPE SPEED

HEIGHT

(RVS)

F

''

F

R

KRC-268A

ADJUSTMENT/EINSTELLUNGEN (MECHA.)

Head Angle Adjustment

Head height alignment procedure

• During FWD transport adjust screws F and F' so that line A of 2-LINE

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

• During RVS transport adjust screws R and R' so that line B of 2-LINE

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

• 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)

Einstellung des Kopfwinkels

Vorgehensweise bei der Kopfhöhen-Einstellung

• Während des Bandlaufs in Vorwärtsrichtung die Schrauben F und F' so einstellen, daß die Linie A eines 2-Linien-Bands (2-LINE TAPE) durch die Mitte der Kopfabschirmplatte (Zentrum des Mittelbereichs) verläuft.

• Während des Bandlaufs in Rückwärtsrichtung die Schrauben R und R' so einstellen, daß die Linie B eines 2-Linien-Bands (2-LINE TAPE) durch die Mitte der Kopfabschirmplatte (Zentrum des Mittelbereichs) verläuft.

• Nachdem die obige Einstellung abgschlossen ist, die Bandlaufrichtung umkehren und die Ausrichtung in Vorwärtsrichtung noch einmal überprüfen. Wenn eine Abweichung festgestellt wird, ist diese Einstellung zu wiederholen. (Verwendetes Band: SCC-1659, hergestellt von A-BEX)

6