JVC KSFX-270 Service manual

SERVICE MANUAL

CASSETTE RECEIVER

KS-FX270

Contents

Safety precaution Disassembly method Adjustment method Description of major ICs

LOUDLOUD

VCR

DISPDISP

SCANSCAN

8 9 10 11 127

Multi Music Scan

Area Suffix

J ---- Northern America

1-2 1-3 1-12 1-16

This service manual is printed on 100% recycled paper.

No.49582

Dec. 2000

KS-FX270

Safety precaution

Burrs formed during molding may be left over on some parts of the chassis. Therefore, pay attention to such burrs in the case of preforming repair of this system.

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Disassembly method

Removing the front panel assembly

(See Fig.1)

Press the eject button in the lower right part of the front panel. Remove the front panel assembly from the body.

Removing the front chassis assembly

(See Fig.2 and 3)

KS-FX270

Front panel assembly

Eject button

Fig.1

Tab a

Prior to performing the following procedure, remove the front panel assembly.

Release the four joint tabs a on both sides of the front chassis assembly and remove the front chassis assembly toward the front.

Tab a

Front chassis assembly

Heat sink

Fig.2

Tab a

Front chassis assembly

Fig.3

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KS-FX270

Removing the heat sink (See Fig.4)

Remove the three screws A on the left side of the body.

Removing the bottom cover

(See Fig.5 and 6)

Prior to performing the following procedure, remove the front panel assembly, the front chassis assembly and the heat sink.

Turn over the body and unjoint the five joints b with the bottom cover and the body using a screwdriver.

Joint b

Joints b

Heat sink

Fig.4

Rear panel

Fig.5

Bottom cover

Joints b

Bottom cover

Joints b

Joint b

Rear panel

Fig.6

1-4

KS-FX270

Removing the main board

(See Fig.7 and 8)

Prior to performing the following procedure, remove the front panel assembly, the front chassis assembly, the heat sink and the bottom cover.

Remove the screw B, the four screws C and the two screws D attaching the rear bracket on the back of the body. Remove the rear panel.

Remove the two screws E attaching the main board on the bottom of the body. Disconnect connector CN701 on the main board in the direction of the arrow.

Rear panel

Fig.7

Main board

Removing the cassette mechanism section

(See Fig.9)

Prior to performing the following procedure, remove the front panel assembly, the front chassis assembly, the heat sink, the bottom cover and the main board.

Remove the four screws F attaching the cassette mechanism section on the back of the top chassis.

Fig.8

Cassette mechanism section

Fig.9

CN901

Top chassis

1-5

KS-FX270

Removing the control switch board

(See Fig.10 to 12)

Prior to performing the following procedure, remove the front panel assembly.

Remove the four screws G attaching the rear cover on the back of the front panel assembly.

Unjoint the six joints c with the front panel and the rear cover.

Remove the control switch board on the back of the front panel.

Front panel

Rear cover

Fig.10

Joints c

Rear cover

Front panel

Joints c

Fig.11

Control switch board

Fig.12

1-6

KS-FX270

Cassette mechanism ass’y

Removing the head amplifier P.W.B.

(See Fig.1 and 2)

For the 6pin harness extending from connector CN402 on the head amplifier P.W.B, disconnect it from the head relay P.W.B.

Disconnect the card wire from connector CN403 on the head amplifier P.W.B.

Remove the screw A attaching the head amplifier P. W . B .

Move the tab a as shown in Fig.2 and remove the head amplifier P.W.B. while moving it in the direction of the arrow.

Removing the cassette mechanism assembly (See Fig.1 to 3)

Disconnect the 6pin harness from connector CN402 and the card wire from CN403 on the head amplifier P.W.B. (Refer to Fig.1 and 2).

Head relay

P.W.B.

6pin harness

CN403

CN402

CN403

Head amplifier P.W.B.

Fig.1

Tab a

Fig.2

Remove the four screws B on the bottom of the cassette mechanism.

Head amplifier P.W.B.

Cassette mechanism ass’y

Fig.3

1-7

KS-FX270

Removing the head relay P.W.B.

(See Fig.4)

Unsolder the soldering b on the head relay P.W.B.

Remove the screw C attaching the head relay P.W.B.

Remove the head relay P.W.B. in the direction of the arrow while releasing the two joints c.

Removing the load arm (See Fig.5)

Remove the E washer attaching the load arm using a pincette or something like that and remove the spring d.

Move the part of the load arm marked upwards to release it from the axis of rotation. Then rotate the load arm in the direction of the arrow to remove it from the cach.

Fig.4

Cach

Load arm

Fig.5

Head relay P.W.B.

Soldering b

E washer

Joint c

Spring d

Removing the sub chassis (See Fig.6)

Prior to performing the following procedure, remove the head relay P.W.B.

Remove the screw D attaching the sub chassis.

Push the tab e in the direction of the arrow to detach the one side of the sub chassis. Then release the sub chassis from the tab f.

Removing the cassette holder and the holder arm in the eject mode

(See Fig.7 and 8)

Prior to performing the following procedure, remove the head relay P.W.B., the load arm and the sub chassis.

Remove the screw E attaching the reinforce bracket.

Remove the reinforce bracket.

Tab f

Sub chassis

Head relay

P.W.B.

Cassette mecha chassis

Cassette holder

Fig.6

Head relay P.W.B.

Tab e

Reinforce bracket

tab g

Push the tab g fixing the cassette holder in the direction of the arrow and open the cassette holder and the holder arm upward until they stop at an angle of 45 degrees. Move the two joints h to the side and remove the cassette holder and the holder arm from the shaft.

1-8

Joint h

Load arm

Holder arm

Fig.7

Joint h

Removing the play head (See Fig.9)

Prior to performing the following procedure, remove the head relay P.W.B.and the sub chassis.

Remove the two screws F attaching the play head (The spring under the play head comes off at the same time).

Shaft

Joint h

Pinch roller ass’y

Fig.8

Play head

KS-FX270

Cassette holder and holder arm

Joint h

Shaft

Pinch roller ass’y

Removing the pinch roller ass’y

(See Fig.9)

Prior to performing the following procedure, remove the head relay P.W.B.and the sub chassis.

Push each tab i in the direction of the arrow and pull out the pinch rollers on both sides.

Removing the reel disc P.W.B.

(See Fig.10)

Unsolder the soldering j on the reel disc P.W.B.

Push the seven tabs k on the bottom of the cassette mechanism assembly in the direction of the arrow.

Removing the motor and the sub motor

(See Fig.10 and 11)

Tab i

Soldering j

Motor

Pinch roller ass’y

Fig.9

Reel disc P.W.B.

Tabs k

Tab i

Spring

Tab i

Cassette mechanism ass’y

Flyhwheel

Belt

Fig.10

Unsolder the two soldering l of the motor and the sub motor.

Release the sub motor from the three tabs m. Push the sub motor upward and pull out it.

Remove the belt on the bottom of the cassette mechanism assembly and remove the two screws G attaching the motor.

ATTENTION:

The motors can be detached before removing the load arm.

Sub motor

Tab m

Load arm

Soldering j

Tab m

Soldering l

Tab m

Soldering l

Motor

Fig.11

1-9

KS-FX270

Removing the flywheel

(See Fig.10 and 12)

Prior to performing the following procedure, remove the head relay P.W.B, the load arm, the sub chassis, the cassette holder, the holder arm and the reel disc P. W . B .

Remove the belt on the bottom of the cassette mechanism ass’y.

Remove the slit washer attaching the flywheel on the upper side of the cassette mechanism ass’y and pull out the flywheel downward. Then remove another flywheel in the same way.

ATTENTION:

When reassembling, make sure to use a new slit washer.

Removing the reel disc ass’y( )

(See Fig.12 to 14)

Soldering j

Motor

Plate

Reel disc P.W.B.

Slit washer

Tab k

Tab o

Cassette mechanism ass’y

Tab k

Belt

Fig.10

Reel driver

The part n

Tabs o

Flyhwheel

Reel disc

ass’y( )

Push aside the gear

Prior to performing the following procedure, remove the head relay P.W.B, the load arm, the sub chassis, the cassette holder and the holder arm.

Disengage the part n inside of the reel driver which engages with the shaft, using a pincette or something like that. Then remove the reel driver from the shaft.

Remove the reel driver spring and the reel table.

The part n

Slit washer

Shaft

Fig.13

The part n

Reel driver

Fig.12

Reel driver

Reel driver spring

Reel disc ass’y( )

1-10

Reel table

Fig.14

KS-FX270

Removing the reel disc ass’y( )

(See Fig.12 to 15)

ATTENTION:

Release the plate from the three tabs o.

Push aside the gear over the reel table using a pincette or something like that.

Remove the reel disc ass’y ( ) as with the reel disc ass’y ( ).

ATTENTION:

Prior to performing the following procedure, remove the reel disc ( ).

Do not break the front panel tab fitted to the metal cover.

Push aside the gear and reattach the reel disc Ass’y( ).

Reel disc ass’y( )

Fig.15

1-11

KS-FX270

Adjustment method

Test instruments reqired for adjustment

1. Digital osclloscope(100MHz)

2. Frequency Counter meter

3. Electric voltmeter

4. Wow & flutter meter

5. Test Tapes

MC-109C

VT724 .......................

VT739 ............For playback frequency measurement

VT712 ....For wow flutter & tape speed measurement

VT703 ..................... For head azimuth measurement

6. Torque gauge .................... Cassette type for CTG-N

...................

for TAPA CURL confirmation (without Padd type)

for DOLBY level measurement

(mechanism adjustment)

Measuring conditions(Amplifier section)

Power supply voltage .............. DC14.4V (10.5 - 16V)

Load impedance ........... 4 (2Speakers connection)

Line out............................................................ 20k

Standard volume position

Balance and Bass,Treble volume .Fader :Center(Indication"0") Loudness,Dolby NR,Sound,Cruise:Off Volume position is about 2V at speaker output with following conditions.Playback the test tape VT721.

AM mode 1000kHz/62dB,INT/400Hz,30%

modulation signal on recieving.

FM mono mode 97.5MHz/66dB,INT/400Hz,22.5kHz

deviation pilot off mono FM stereo mode 1kHz,67.5kHz dev. pilot7.5kHz dev. Output level 0dB(1 V,50 /open terminal)

1-12

Arrangement of adjusting & test points

Cassette mechanism (Surface)

Motor assembly

KS-FX270

Tape speed adjust

Head section view

Azimuth screw A (Forward)

Playback head

Azimuth screw B (Reverse)

Azimuth screw A (Forward)

Playback Head

1-13

KS-FX270

Main board

Information for using a car audio service jig

1. We're advancing efforts to make our extension cords common for all car audio products. Please use this type of extension cord as follows.

2. As a U-shape type top cover is employed, this type of extension cord is needed to check operation of the mechanism assembly after disassembly.

3. Extension cord : EXTKSRT002-18P ( 18 pin extension cord ) For connection between mechanism assembly and main board assembly. Check for mechanism driving section such as motor ,etc..

Disassembly method

1. Remove the bottom cover.

2. Remove the front panel assembly.

3. Remove the top cover .

4. Install the front panel.

5. Confirm that current is being carried by connecting an extension cord jig.

Note Available to connect to the CP701 connector when installing the front panel.

Extension cord EXTKSRT002-18P

Cassette mechanism

to Cassette mechanism

EXTKSRT002-18P

Main board

Front panel assembly

to Main board

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Mechanism adjustment section

Item Adjusting & Confirmation Methods Adjust Std. Value

1. Tape running adjustment

2. Azimuth adjustment confirmation

a) At Forward playmode, using mirror tape, make adjustment with Azimuth screw A and Azimuth screw B, without curl of 4 parts of head tape guide. b) At Reverse play mode, using mirror tape, make adjustment with Azimuth screw A and Azimuth screw B, without tape curl of 4 parts of head guide. c) At Forward / Reverse play mode, make confirmation of no tape curl of 4 parts of head tape guide.

a) At forward play mode, make adjustment of peak of Lch / Rch output with Azimuth screw A. * For Oscilloscope litharge corrugation, set 45 as standard. b) At Reverse play mode, make adjustment of peak of Lch / Rch output with Azimuth screw B. * For Oscilloscope litharge corrugation, set 45 as standard. c) With AC volt meter confirm the difference of output for 4ch between Lch / Rch at forward play mode and Lch / Rch Reverse play mode being within 3.0dB. d) After operation, make confirmation of Lch / Rch azimuth output being within 1.0dB from adjustment value.

KS-FX270

Azimuth screw A

Azimuth screw B

2.Tape Speed and Wow & Flutter

HEAD

Tape guide

HEAD TAPE

1.Check to see if the reading of the frequency counter & W ow flutter meter is within 2940-3090 Hz( FWD/REV ), and less than 0.35% ( JIS RMS ).

2.In case of out of specification, adjust the motor with a builtin volume resistor .

Tape curl NG

Phase

Built-in volume resistor

Tape Speed 2940-3090Hz Wow&Flutter Less than

0.35% (JIS RMS)

3.Playback Frequency response

1.Play the test tape ( VT724 : 1kHz ) back and set the volume position at 2V .

2.Play the test tape ( VT739 )back and confirm 0 3dB at1kHz/ 10kHz and -4+2dB at 1kHz/63Hz.

3.When 10kHz is out of specification, it will be necessary to read adjust the azimuth.

Speaker out 1kHz/10kHz : 0dB 3dB, 63Hz/1kHz : -4dB+2dB,

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