JVC MXGT-88 Service manual

SERVICE MANUAL

COMPACT COMPONENT SYSTEM

MX-GT88

B ------------------------ U.K. E ---- Continental Europe EN ----- Northern Europe EV ------- Eastern Europe

Area suffix

STANDBY

ECO

COMPACT COMPONENT SYSTEM MX-GT88

REC START

/ STOP

CD REC

POP

START

DUBBING

CLASSIC

DISPLAY

MP3

PHONES

SOUND TURBO

SUBWOOFER LEVEL

TUNING

BEEP

DISC CHANGE

REPEAT

DANCE

PROGRAM

RANDOM

STADIUM

CLOCK / TIMER

SET

PRESET

CANCEL / DEMO

TAPE A / B

SELECT

DISPLAY MODE

RDS MODE

TUNING

EJECTEJECT

SP-MXGT88 SP-MXGT88CA-MXGT88

Contents

Safety Precautions Important for laser produbts Preventing static electricity Disassembly method Wiring connection Adjustment method

1-2 1-4 1-5 1-6 1-19 1-20

Flow of functional operation until TOC read Maintenance of laser pickup Replacement of laser pickup Trouble shooting Description of major ICs

1-24 1-25 1-25 1-26 1-30~44

No.22075

Jul. 2003

MX-GT88

1. This design of this product contains special hardware and many circuits and components specially for safety purposes. For continued protection, no changes should be made to the original design unless authorized in writing by the manufacturer. Replacement parts must be identical to those used in the original circuits. Services should be performed by qualified personnel only.

2. Alterations of the design or circuitr y of the product should not be made. Any design alterations of the product should not be made. Any design alterations or additions will void the manufacturer`s warranty and will further relieve the manufacture of responsibility for personal injury or property damage resulting therefrom.

3. Many electrical and mechanical parts in the products have special safety-related characteristics. These

characteristics are often not evident from visual inspection nor can the protection afforded by them necessarily be obtained by using replacement components rated for higher voltage, wattage, etc. Replacement par ts which have these special safety characteristics are identified in the Parts List of Service Manual. Electrical components having such features are identified by shading on the schematics and by ( ) on the Parts List in the Service Manual. The use of a substitute replacement which does not have the same safety characteristics as the recommended replacement parts shown in the Parts List of Service Manual may create shock, fire, or other hazards.

4. The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the like to be separated from live parts, high temperature parts, moving parts and/or sharp edges for the prevention of electric shock and fire hazard. When service is required, the original lead routing and dress should be observed, and it should be confirmed that they have been returned to normal, after re-assembling.

5. Leakage currnet check (Electrical shock hazard testing) After re-assembling the product, always perform an isolation check on the exposed metal parts of the product (antenna terminals, knobs, metal cabinet, screw heads, headphone jack, control shafts, etc.) to be sure the product is safe to operate without danger of electrical shock. Do not use a line isolation transformer during this check.

Plug the AC line cord directly into the AC outlet. Using a "Leakage Current Tester", measure the leakage current from each exposed metal parts of the cabinet, particularly any exposed metal part having a return path to the chassis, to a known good earth ground. Any leakage current must not exceed 0.5mA AC (r.m.s.).

Alternate check method Plug the AC line cord directly into the AC outlet. Use an AC voltmeter having, 1,000 ohms per volt or more sensitivity in the following manner. Connect a 1,500 10W resistor paralleled by a 0.15 F AC-type capacitor between an exposed metal part and a known good earth ground. Measure the AC voltage across the resistor with the AC voltmeter. Move the resistor connection to each exposed metal part, particularly any exposed metal part having a return path to the chassis, and meausre the AC voltage across the resistor. Now, reverse the plug in the AC outlet and repeat each measurement. Voltage measured any must not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5 mA AC (r.m.s.).

0.15 F AC TYPE

1500 10W

Good earth ground

AC VOLTMETER (Having 1000 ohms/volts, or more sensitivity)

Place this probe on each exposed metal part.

1. This equipment has been designed and manufactured to meet international safety standards.

2. It is the legal responsibility of the repairer to ensure that these safety standards are maintained.

3. Repairs m ust be made in accordance with the relevant safety standards.

4. It is essential that safety critical components are replaced by approved parts.

5. If mains voltage selector is provided, check setting for local voltage.

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.

In regard with component parts appearing on the silk-screen pr inted side (parts side) of the PWB diagrams, the parts that are printed over with black such as the resistor ( ), diode ( ) and ICP ( ) or identified by the " " mark nearby are critical for safety.

(This regulation does not correspond to J and C version.)

1-2

MX-GT88

(U.K only)

2. Any unauthorised design alterations or additions will void the manufacturer's guarantee ; further more the manufacturer cannot accept responsibility f or personal injury or property damage resulting therefrom.

3. Essential safety critical components are identified by ( ) on the Parts List and by shading on the schematics, and must never be replaced by parts other than those listed in the manual. Please note

however that many electrical and mechanical parts in the product have special safety related characteristics. These characteristics are often not evident from visual inspection. Parts other than specified by the manufacturer may not have the same safety characteristics as the recommended replacement parts shown in the Parts List of the Service Manual and may create shock, fire, or other hazards.

4. The leads in the products are routed and dressed with ties, clamps, tubings, barriers and the like to be separated from live parts, high temperature parts, moving parts and/or sharp edges for the prevention of electric shock and fire hazard. When service is required, the or iginal lead routing and dress should be observed, and it should be confirmed that they have been returned to normal, after re-assembling.

1. Service should be performed by qualified personnel only.

2. This equipment has been designed and manufactured to meet international safety standards.

3. It is the legal responsibility of the repairer to ensure that these safety standards are maintained.

4. Repairs must be made in accordance with the relevant safety standards.

5. It is essential that safety critical components are replaced by approved parts.

6. If mains voltage selector is provided, check setting for local voltage.

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.

1-3

MX-GT88

Important for laser products

1.CLASS 1 LASER PRODUCT

2.DANGER : Invisible laser radiation when open and inter

lock failed or defeated. Avoid direct exposure to beam.

3.CAUTION : There are no serviceable parts inside the Laser Unit. Do not disassemble the Laser Unit. Replace the complete Laser Unit if it malfunctions.

4.CAUTION : The compact disc player uses invisible laserradiation and is equipped with safety switches whichprevent emission of radiation when the drawer is open and the safety interlocks have failed or are de feated. It is dangerous to defeat the safety switches.

5.CAUTION : If safety switches malfunction, the laser is able to function.

6.CAUTION : Use of controls, adjustments or performance of procedures other than those specified herein may result in hazardous radiation exposure.

CAUTION

REPRODUCTION AND POSITION OF LABELS

Please use enough caution not to see the beam directly or touch it in case of an adjustment or operation check.

CLASS 1 LASER PRODUCT

WARNING LABEL

1-4

Preventing static electricity

MX-GT88

1. Grounding to prevent damage by static electricity

Electrostatic discharge (ESD), which occurs when static electricity stored in the body, fabric, etc. is discharged, can destroy the laser diode in the traverse unit (optical pickup). Take care to prevent this when performing repairs.

2. About the earth processing for the destruction prevention by static electricity

In the equipment which uses optical pick-up (laser diode), optical pick-up is destroyed by the static electricity of the work environment. Be careful to use proper grounding in the area where repairs are being performed.

2-1 Ground the workbench

Ground the workbench by laying conductive material (such as a conductive sheet) or an iron plate over it before placing the traverse unit (optical pickup) on it.

2-2 Ground yourself

Use an anti-static wrist strap to release any static electricity built up in your body.

(caption) Anti-static wrist strap

Conductive material (conductive sheet) or iron plate

3. Handling the optical pickup

1. In order to maintain quality during transport and before installation, both sides of the laser diode on the replacement optical pickup are shorted. After replacement, return the shorted parts to their original condition. (Refer to the text.)

2. Do not use a tester to check the condition of the laser diode in the optical pickup. The tester's internal power source can easily destroy the laser diode.

4. Handling the traverse unit (optical pickup)

1. Do not subject the traverse unit (optical pickup) to strong shocks, as it is a sensitive, complex unit.

2. Cut off the shorted part of the flexible cable using nippers, etc. after replacing the optical pickup. For specific details, refer to the replacement procedure in the text. Remove the anti-static pin when replacing the traverse unit. Be careful not to take too long a time when attaching it to the connector.

3. Handle the flexible cable carefully as it may break when subjected to strong force.

4. It is not possible to adjust the semi-fixed resistor that adjusts the laser power. Do not turn it

Attention when CD mechanism assembly is decomposed

*Please refer to "Disassembly method" in the text for pick-up and how to detach the CD mechanism assembly.

1. Remove the CD changer unit.

2. Remove the CD changer mechanism.

3. Solder is put up before the card wire is removed from the pickup unit connector on the CD mechanism assembly. (When the card wire is removed without putting up solder, the CD pick-up assembly might destroy.)

4. Please remove solder after connecting the card wire with the pickup unit connector when you install picking up in the substrate.

Card wire

Picup unit connector

Soldering

Fig.2

CD changer unit

Fig.1

Card wire

Picup unit connector

CD changer mechanism

1-5

MX-GT88

Disassembly method

Removing the metal cover (See Fig.1)

Remove the three screws A attaching the metal cover on the back of the body.

Remove the six screws B attaching the metal cover on both sides of the body.

Remove the metal cover from the body by lifting the rear part of the cover.

ONE POINT

How to eject the CD tray manually (see fig.2)

Turn the loading pulley gear at the bottom of the CD changer unit as shown in Fig.2 and draw the CD tray toward the front.

Metal cover

(both sides)

Fig.1

Loading pulley gear (See <CD changer unit>fig.1)

Removing the CD tray fitting

(See Fig. 3)

Prior to performing the following procedure, eject the CD tray.

After drawing the lower part of the tray fitting toward

1. the front, remove the five claws. Then, while moving the tray fitting upward, remove it.

Removing the CD changer unit

(See Fig.4 to 7)

Prior to performing the following procedure, remove the metal cover and CD tray fitting.

Remove the card wire attached to CD changer unit on the adhesion tape.

Disconnect the card wire from the connector CW105 on the CD board.

Disconnect the harness from the connector CW104 on the main board.

Remove the two screws C attaching the CD changer unit to the rear panel.

Fig.2

Joint

CD tray fitting

Claw

Fig.3

Card wire

CD changer unit

Remove the two screws D attaching the CD changer unit to both sides of the front panel assembly.

Draw the CD changer unit upward from behind while pulling the rear panel outward.

1-6

Adhesion tape

Fig.4

MX-GT88

CW105

CD board

CD changer unit

CW104

Main board

Fig.5

Removing the front panel assembly

(See Fig.8 to 10)

Prior to performing the following procedure, remove the metal cover and CD changer unit.

Front panel

assembly

(both sides)

Front panel

assembly

Fig.6

CD changer unit

Fig.7

CW101

CW109

CW110

Rear panel

Main board

ACW1

ACW2

CW108

Disconnect the card wire from the connector CW101 on the main board.

Disconnect the harness from the connector CW108, CW109 and CW110 on the main board.

Remove the screw E fixiing the lug wire.

Remove the two screws F attaching the front panel assembly to both sides of the body.

Remove the screw G attaching the main board to the front panel assembly.

Remove the screw H attaching the front panel assembly to bottom of the body.

Release the two joints1 and two joints2, and detach the front panel assembly toward the front.

Joint1 (both sides)

(both sides)

Fig.8

Main board

Fig.9

(fixing the lug wire)

(both sides)

Amp. board

Front panel assembly

Joint1 (both sides)

1-7

MX-GT88

)

Removing the heat sink & amp. board

(See Fig.8, 11 and 12)

Prior to performing the following procedure, remove the metal cover and CD changer unit.

Disconnect the card wire from the connector ACW1 and the harness from the connector ACW2 on the amp. board.

Remove the four screws I attaching the heat sink cover to the rear panel. Remove the heat sink cover.

Remove the four screws J attaching the heat sink and two screws K attaching the speaker terminal to the rear panel.

After moving the heat sink upward, remove the claws. Then pull out the heat sink & amp. board inward.

Heat sink

cover

Joint2

Fig.10

(Bottom side

Rear panel

Removing the tuner board (See Fig.12 and 13)

Prior to performing the following procedure, remove the metal cover.

Disconnect the card wire from the connector CON01 on the tuner board.

Remove the two screws L attaching the tuner board to the rear panel.

Removing the rear panel (See Fig.12)

Prior to performing the following procedure, remove the metal cover, CD changer unit, heat sink & amp. board and tuner board.

Remove the three screws M and three screws N attaching the rear panel.

Claws

Heat sink

Main board

Fig.11

Rear panel

L K

Speaker terminal

Fig.12

CON01

Rear panel

1-8

Tuner board

Fig.13

MX-GT88

Removing the main board (See Fig. 14)

Prior to performing the following procedure, remove the metal cover, CD changer unit and rear panel.

Disconnect the card wire from the connector CW101, and the harness from the connector CW108, CW109, CW110 and CW11, and the power cord from the connector PW103 on the main board.

Disconnect the harness from the connector PCW1 on the fuse board.

Remove the screw G attaching the main board to the front panel assembly. (See Fig.9)

Remove the two screws O attaching the heat sink to the bottom chassis.

Removing the power cord (See Fig. 14)

Prior to performing the following procedure, remove the metal cover, CD changer unit and rear panel.

CW108

Fuse board

PCW1

PW102

Bottom chassis

Power supply board

Power ICs solder point

CW101

CW109

CW110

Main board

Heat sink

PW10

CW11

Power cord

Power cord stopper

Fig.14

Heat sink

Disconnect the power cord from the connector PW103 on the main board and pull up the power cord stopper upward.

Removing the power ICs

(See Fig.15 and 16)

Prior to performing the following procedure, remove the metal cover, CD changer unit and heat sink & amp. board.

Unsolder the power ICs solder points.

Remove the four screws P attaching the power ICs to the heat sink.

Removing the power transformer

(See Fig .17)

Prior to performing the following procedure, remove the metal cover, CD changer unit and heat sink & amp. board.

Disconnect the harness from the connector PW102 on the power supply board.

Fig.15

Fig.16

Power transformer

Amp. board (reverse side)

Heat sink

Amp. board

Fuse board

PCW1

Disconnect the harness from the connector PCW1 on the fuse board.

Remove the four screws Q attaching the power transformer on the bottom chassis.

Bottom

chassis

Power supply board

PW102

Fig.17

1-9

MX-GT88

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

Removing the CD switch board (See Fig.1)

Disconnect the card wire from the connector UCW03 on the CD switch board.

Remove the five screws A attaching the CD switch board.

Removing the front board (See Fig.1 and 2)

Pull out the sound mode knob, volume knob, and preset knob from the front side of front panel assembly.

Disconnect the card wire from the connector UCW02 on the front board and the connector on the mecha. board.

Remove the fifteen screws B attaching the front board.

Connector

Mecha.

board

Front panel assembly (inner side)

Fig.1

CD switch board

UCW03

Front board

UCW02 UCW01

Disconnect the card wire from the connector UCW01 on the front board.

Removing the headphone jack board (See Fig.3)

Prior to performing the following procedure remove the front board.

You can pull out the headphone jack board.

Removing the cassette mechanism assembly (See Fig.3)

Disconnect the card wire from the connector on the mecha. board.

Remove the six screws C attaching the cassette mechanism assembly.

Connector

Mecha.

board

Sound mode knob Volume knob

Preset knob

Fig.2

Front panel assembly (inner side)

Headphone

jack board

1-10

(fixing the lug wire)

Fig.3

Cassette mechanism

assembly

MX-GT88

Prior to performing the following procedure, remove the CD changer unit.

Removing the CD tray (See Fig.1 and 2)

Turn the black loading pulley gear on the under side of the CD changer unit in the direction of the arrow and draw the CD tray toward the front until it stops.

Disconnect the card wire from connector CW103 on the CD board.

Push down the two tray stoppers marked a and pull out the CD tray.

Loading pulley

gear

CD changer uint (reverse side)

CD tray

CD board

CW103

Fig.1

a (Tray stopper)

Reinstall the CD tray (See Fig.3 and 4)

Align the gear-cam with the gear-tray as shown fig.3, then mount the CD tray.

When assembling the CD tray, take extreme care not engage with gear - synchro.

Gear-cam

Gear-convert

Gear-cam

timing point

CD tray

(Tray stopper)

CW103 (on the CD board)

Fig.2

Gear-tray

Gear-synchro

Gear-convert

Gear-tray

CD tray

Gear-tray

Fig.3 Fig.4

1-11

MX-GT88

Removing the sensor board (See Fig.5)

Prior to performing the following procedure, remove the CD tray.

Remove the screw A attaching the sensor board on the CD tray.

Remove the sensor board releasing the two tabs a.

Disconnect the harness from the connector CW1 on the sensor board.

Removing the turn tray motor (See Fig.6 and 7)

Prior to performing the following procedure, remove the CD tray and sensor board.

Remove the screw B attaching the turn tray. Detach the turn tray from the base tray.

Pull outward the tab b attaching the turn tray motor on the base tray and detach the turn tray motor.

CD tray (reverse side)

CW1

Tab a

Sensor board

Fig.5

Turn tray

Introductory notes: Base tray + Turn tray = CD tray

Base tray

Fig.6

Turn tray motor

Base tray (upper side)

Tab b

Fig.7

1-12

Removing the belt, the CD board and the switch board (See Fig.8 and 9)

Prior to performing the following procedure, remove the CD tray.

Detach the belt from the pulley on the upper side of the CD changer unit (Do not stain the belt with grease).

Disconnect the card wire from the pickup unit connector on the under side of the CD changer unit.

Attention : Solder is put up before the card wire is removed from the pick-up unit connector on the CD mechanism assembly. (When the card wire is removed without putting up solder, the CD pick-up unit assembly might destroy.)

Disconnect the motor wire harness from connector on the CD board.

Remove the screw C attaching the switch board and release the two tabs e attaching the switch board outward and detach the switch board.

Remove the two screws D attaching the CD board. First release the two tabs f and two tabs g attaching the motor, then release the CD board.

If the tabs f and g are hard to release, it is recommendable to unsolder the two soldered parts on the motor terminal of the CD board.

Tabs e

Switch board

CW3

CD changer unit

Fig.8

CD board

Tabs g

Soldered parts

CD mechanism board

motor connecter

Pickup unit connector

Card wire

MX-GT88

Belt

Motor

Tabs f

Soldering

Picup unit connector

Fig.9

1-13

MX-GT88

Removing the CD mechanism holder assembly (mechanism included)

(See Fig.10 to 13)

Disconnect the harness from connector on the CD mechanism board in the CD mechanism assembly on the under side of the CD changer unit. Disconnect the card wire from the pickup unit connector.

Attention : Solder is put up before the card wire is removed from the pick-up unit connector on the CD mechanism assembly. (Refer to Fig.9) (When the card wire is removed without putting up solder, the CD pick-up unit assembly might destroy.)

Motor connecter

CD changer unit

CD mechanism holder assembly

Pickup unit connector

Remove the screw E attaching the shaft on the right side of the CD mechanism holder assembly. Pull outward the stopper fixing the shaft on the left side and remove the CD mechanism holder assembly from behind in the direction of the arrow y.

Turn the CD mechanism holder assembly half around the lift up slide shaft h of the CD mechanism holder assembly until the turn table is reversed, and pull out the CD mechanism holder assembly.

Lift up slide shaft

Fig.10

Stopper

CD mechanism holder assembly

Fig.11

Lift up slide shaft n

1-14

CD mechanism holder assembly

Fig.13

CD mechanism holder assembly

Fig.12

MX-GT88

•

Removing the CD mechanism holder from the CD chager unit. (Refer to "Removing the CD mechanism holder assembly" )

Removing the pickup unit (

1. Removing the cut washer on the feed gear sleeve and pull out the feed gear.

2. Remove the two screws A fixing the pickup shaft.

3. Removing the pickup unit.

Removing the motor board

1. Unsolder the motor terminal on the motor board.

2. Remove the moter board.

Removing the feed motor (

Remove the two motor fixing screws at B and removing the feed motor.

See Fig.1)

(See Fig.2)

See Fig.1)

Motor board

Shutter

Cut washer

Fig.1

Unsolder

Pickup unit

Feed Gear

Feed motor

Shaft

Removing the spindle motor

The spindle motor cannot be removed as a single unit. When removing the spindle motor, change the chasis and turntable together as aunit.

Spindle motor

Unsolder

Fig.2

1-15

MX-GT88

Prior to performing the following procedure, remove the

cassette mechanism assembly.

Removing the R/P head. (See Fig.1 and 2)

Remove the screw A on the right side of the R/P head.

Remove the screw B on the left side of the R/P head.

Remove the erase head.

Remove the screw C fixing the erase head.

(See Fig.1)

E. Head

R/P Head

Pinch roller

Fig.1

Remove the pinch roller.

Pull out the pinch roller stopper.

1. Pull out the pinch roller.

(See Fig.3)

Spring

Pinch roller

R/P Head

Fig.2

Pinch roller

stopper

Fig.3

1-16

MX-GT88

Removing the motor

Slide the plastic cover in the direction of the arrow, and remove the three claws. Then remove the plastic cover.

Remove the two screws D fixing the motor. Be careful to grease's splash when the drive belt comes off.

Unsolder the motor terminal.

(See Fig. 4 to 6)

Removing the mechanism board

Unsolder the four solder parts a and the four solder parts b.

Remove the two screws E attaching the mecha. board.

(See Fig. 5)

Removing the flywheel

Remove the cut-washer at c from the capstan shaft, then remove the flywheel. When reassembling the flywheel, be sure to use new washers as they cannot be reused.

(See Fig. 7 and 9)

Solder

part

Claw

Fig.4

Motor

terminal

Solder

part

Solder part

Plastic cover

Mecha. board

Flywheel

Washer

FR belt

Fig.8

Sleeve

FR belt

Drive belt

Motor

Drive belt

Fig.5

Motor

Drive belt

Fig.6

Fig.9

Capstan

washer

Fig.7

1-17

MX-GT88

< Speaker section >

It is exchange in a unit. Please do not decompose as much as possible.

Removing the duct (See Fig. 1)

Remove the foru screws A and two screws B attaching the duct, and remove the duct.

Duct

(both sides)

Fig.1

1-18

MX-GT88

Wiring connection

Amp. board

Front board

UCW02

AH39-00295A

3809-001413

ACW2

ACW1

CD switch board

3809-001228

UCW03

UCW04

UCW05

UCW01

Power transformer

PW102

PCW1

3809-001121

AH39-00338A

AH39-00466A

CD mechanism

AH39-20561P

CW2

AAN1

CW1

CW3

AH38-12001A

Color codes are shown below. 1 Brown 2 Red 3 Orange 4 Yellow 5 Green 6 Blue 7 Violet

8 Gray 9 White 0 Black

3809-001034

CW102

CW103

CW105

CW106

CD board

CW107

CW101

CW104

CW3

AH39-00060A

3809-001211

3809-001434

CON01

3809-001259

CW103

CW105

CW104

PW103

CW11

CW106

AH39-00247A

CW108

Main board

CW110

Tuner board

CW101

CW111

CW109

CW107

CW01B

Headphone J.board

AH39-00022A

AH39-20002D

1-19

MX-GT88

Adjustment method

1. Tuner

ITEAM

Received FREQ. Adjustment

point

Output

* Adjustment Location of Tuner PCB

AM(MW) OSC Adjustment

522~1629 KHz

1~7.0 0.5V

MAIN PCB

AM(MW) RF Adjustment

594 KHz

Maximum Output(Fig.1)

VT GND

TESTER

1-20

Fig.1 OSC Voltage

FM THD Adjustment

MX-GT88

SSG FREQ.

98 MHz

Adjustment point

FM DETECTOR COIL

(FM DET)

Output

60 dB

Minumum Distortion (0.4% below) (Fig.2)

FM Search Level Adjustment

SSG FREQ. Adjustment

point

(SVR1)

BEACON SENSITIVITY SEMI-VR(10K )

98 MHz

Output GND

FM Antenna Terminal

SET

FM S.S.G

Speaker Terminal

output

Distortion Meter

Fig.2 IF CENTER and THD Adjustment

28 dB

FM Antenna

Input

Oscilloscope

Input

SET

Output

28 dB(

2dB)

Adjust SVR1 (Fig.3)

*Adjust FM S.S.G level to 28dB

AM(MW) I.F Adjustment

SSG FREQ. Frequency

450 kHz 522 kHz

Adjustment point

AM IF

Maximum output (Fig.4)

FM S.S.G

GND

FM IN

Fig.3 FM Auto Search Level Adjustment

60cm

OUTPUT

AM SSG 450KHZ

AM ANT IN

20 k

AM IF

Speaker Terminal

INPUT

VTVM Oscilloscope

OUTPUT

Fig.4 AM I.F Adjustment

1-21

MX-GT88

2. Cassette Deck

To adjust tape speed

Notes

1) Measuring tape: i) VT-712/MTT-111(or equivalent) (Tapes recorded with 3kHz) ii) AC-225/MTT-5512(or equivalent)

2) Connect the cassette deck to the frequency counter as in fig.1.

Cassette Deck

SPK OUT

Frequency Counter

output

Fig.1

Pre-Setup Condition

NOR

1 3KHz

SPEED Control

SPK OUT (connected to the frequency counter)

1) Deck 1:VT-712

2) Press PLAY SW button

To Adjust

Turn VSR1 to left and right (FRONT PCB)

3) Deck 2:Same as above

To adjust plabyback level/REC

Notes

1) Before the actual adjustment, clean the play/recording head.

2) Measuring tape : i) VT-703/MTT-114N(or equivalent 10kHz AZIMUTH control)

ii) AC-225/MTT-5512(or equivalent)

3) The cassette deck is connections as shown in fig.2.

MAIN PCB

SPK OUT

(GND)

Fig.2

VTVM

In Out

RemarkStandardPre-SetupItemStep

range

Oscilloscope

1. Adjust Deck 1 Play Level

Pre-Setup Condition

AZIMUTH1 SPK OUT

(VTVM is connected to the scope)

1-22

After putting VT-703 into Deck 1

- Press FWD PLAY button.

To Adjust

Turn the control screw to as shownin Fig.3.

Max output and same phase (both channels)

RemarkStandardPre-SetupItemStep

After adjustment secure it with REGION LOCK.

2. Adjust Deck 2 Play Level/REC BIAS

MX-GT88

AZIMUTH1

Recording Bias Voltage

Pre-Setup Condition

SPK OUT (VTVM is connected to the scope)

Fig.4

Recording /Play head

AZIMUTH control screw (FWD Play)

After putting VT-703 into Deck 2

1)Press FWD PLAY button.

After putting AC-225 into Deck 2

1)Press REC PLAY button.

2)TAPE PCB JCW3, connectted to VTVM

To Adjust

Turn the control screw to as shown in Fig.3.

Turn JSR2L, JSR2R to the right and left

Max output and same phase (both channels)

CHECK TO 7mV(

0.5mV)

RemarkStandardPre-SetupItemStep

After adjustment secure it with REGION LOCK.

AZIMUTH control screw (RVS Play)

Audio OSC.

Fig.3

AUX IN

SET (MAIN PCB)

SPK OUT

Fig.4

VTVM

IN OUT

Oscilloscope

1-23

MX-GT88

Flow of functional operation until TOC read

Power ON

Play Key

RESET a CD LSI

Check Point

Confirm that the voltage at the pin17 of KB9226(IC101) is "L" "H".

LIMIT SW ON

SET Default value of TE gain, TE balance

Automatic adjusting of

focus bias

Automatic adjusting of

FE offset

Automatic adjusting of

TE offset

LASER power ON

Detection of disk

Confirm that the voltage at the pin33 of KB9226(IC101) is "H" "L" "H".

Confirm that the voltage at the pin37 of KB9226(IC101) is 3.5V.

Tracking error waveform at TOC reading

Pin 34 of KB9226 (IC101)

Approx

0.4V

2.50V

Disc states to rotate

Approx.3.7sec

Disc is rotated

Automatic adjusting of

TE balance

Automatic adjusting of

TE gain

TOC reading

Play a disc

Confirm that the signal from pin24 of KB9226(IC101) is 3.5V as a accelerated pulse during approx.1.96s.

Confirm the waveform of the Tracking error signal at the pin 34 of KB9226(IC101).

Confirm the eye-pattern at the pin2 of KB9226(IC101).

1-24

Maintenance of laser pickup

MX-GT88

(1) Cleaning the pick up lens Before you replace the pick up, please try to clean the lens with a alcohol soaked cotton swab.

(3) Semi-fixed resistor on the APC PC board

The semi-fixed resistor on the APC printed circuit board which is attached to the pickup is used to adjust the laser power. Since this adjustment should be performed to match the characteristics of the whole optical block, do not touch the semi-fixed resistor. If the laser power is lower than the specified value, the laser diode is almost worn out, and the laser pickup should be replaced. If the semi-fixed resistor is adjusted while the pickup is functioning normally, the laser pickup may be damaged due to excessive current.

(2) Life of the laser diode When the life of the laser diode has expired, the following symptoms will appear.

1. The level of RF output (EFM output : amplitude of eye pattern) will below.

Is the level of

RF OUT under

1.1V 0.2Vp-p?

YES

O.K

Replace it.

Replacement of laser pickup

Turn off the power switch and,disconnect the power cord from the ac outlet.

Replace the pickup with a normal one.(Refer to "Pickup Removal" on the previous page)

Plug the power cord in,and turn the power on. At this time,check that the laser emits for about 3seconds and the objective lens moves up and down. Note: Do not observe the laser beam directly.

Play a disc.

Check the eye-pattern at TP1.

Finish.

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