BBK 921S Service Manual

CONTENTS

1. SAFETY PRECAUTIONS……………………………………………………….. 1

1.1 GENENRAL GUIDELINES……………………………………………………….. 1

2. PREVENTION OF ELECTRO STATIC DISCHARGE(ESD) TO ELECTROSTATICALLY SENSITIVE(ES) DEVICES………………………………………………………. 1

3. PRECAUTION OF LASTER DIODE……………………………………………. 2

4. GENERAL DESCRIPTION……………………………………………………… 3

5. PREVENTION OF STATIC ELECTRICITY DISCHARGE…………………….. 5

5.1 GROUNDING FOR ELECTROSTATIC BREAKDOWN PREVENTION……… 5

5.1.1 WORKTABLE GROUNDING…………………………………………………… 5

5.1.2 HUMAN BODY GROUNDING…………………………………………………. 5

5.1.3 HANDING OF OPTICAL PICKUP……………………………………………… 5

5.2 HANDING PRECAUTIONS FOR TRAVERSE UNIT(OPTICAL PICKUP).. 5

6. ASSENBLING AND DISASSEMBLING THE MECHANISM UNIT…….. 6

6.1 DISASSEMBLY PROCEDURE………………………………………………… 6

6.2 TERMINAL P.C.B………………………………………………………………. 6

6.3 CLAMP PLATE UNIT………………………………………………………….. 7

6.4 TRAY…………………………………………………………………………… 7

6.5 TRAVERSE BLOCK…………………………………………………………… 8

6.6 TRAVERSE GEAR……………………………………………………………… 8

6.7 OPTICAL PICKUP UNIT……………………………………………………… 9

6.7.1 PRECAUTIONS IN OPTICAL PICKUP REPLACEMENT…………………… 9

6.8 DISASSEMBLING THE MIDDLE CHASSIS…………………………………. 11

6.9 DISASSENBLING THE TRAVERSE GRAR A………………………………... 11

6.10 DISASSEMBLING THE SPINDLE MOTOR UNIT…………………………… 11 7 Electrical Confirmation………………………………………………………….. 12

7.1 VIDEO OUTPUT(LUMINANCE SIGNAL) CONFIRMATION………………… 12

7.2 VIDEO OUTPUT(CHROMINANCE SIGNAL) CONFIRMATION

8. MPEG CHECK WAVEFORM 14 9 IC BLOCK DIAGRAM & DESCRIPTION………………………………….. 16 10 BLOCK DIAGRAM…………………………………………………………… 35

11 SCHEMATIC & PCB WIRING DIATRAM....................................................................36

12 EXPODED VIEWS…………………………………………………………….

13. SPARE PARTS LIST..................................................................................

……………. 13

49 50

1.SAFETY PRICAUTIONS

1.1 GENERAL GUIDELINES

1.When servicing,observe the original lead dress.ifa short circuit is found,replace all parts which have been overheated or damaged by the short circuit.

2.After servicing,see to it that all the protective devices such as insulation bamiers,insulation papers shields are properly installed.

3.After servicing,make the following leakage current checks to prevent the customer from being exposed to thock hazards.

2.PREVENTION OF ELECTRO STATIC DISCHARGE(ESD) TO ELECTROSTATECALLY

SENSITIVE(ES) DEVICES

Some semiconductor(solid state)devices can be damaged easily by static electricity.Such components commonly are called Electrostatically Sensitive(ES)Devices.Examples of typical ES devices are integrated circuits and some field-effect transistorsand semiconductor chip components.The following techniques should be used to help reduce the incidence of component damage caused by electro static discharge(ESD).

1.Immediately before handling any semiconductor component or semiconductor-equipped assembly,drain off any ESDon your body by touching a known earth ground.Alteatively,obtain and wear a commercially availabel discharging ESD wrist strap,which should be removed for potential shock reasons prior to applying power to the unit under test.

2.After removing an electrical assembly equipped with ES devices,place the assembly on a conductive surface such as alminum foil,to prevent electrostatic charge buildup or exposure of the assembly.

3.Use only a grounded-tip soldering iron to solder or unsolder ES devices.

4.Use only an anti-static solder removal device.Some solder removal devices not classified as anti-static (ESD protected)can generate electrical charge sufficient to damage ES devices.

5.Do not use freon-propelled chemicals.These can generate electrical charges sufficient to damage ES devices.

6.Do not remove a replacement ES device from its protective package until immediately before you are ready to install if.(Most replacement ES devices are packaged with leads electrically shorted together by conductive foam,alminum foil or comparable conductive material).

7.Immediately before removing the protective material from the leads of a aeplacement ES device,touch the protective material to the chassis or circuit assembly into which the device will be installed. Caution Be sure no power is applied to the chassis or circuit,and observe all other safety precautions.

8.Minimize bodily motions when handling unpackaged replacement ES devices.(Otherwise hamless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity(ESD)

notice (1885x323x2 tiff)

１

3. Precaution of L aster Diode

4.General Description

4.1 Compatible Disc Types

4.2

5.PREVERTION OF STATIC ELECTRICITY DISCHARGE

The laser diode in the traverse unit (optical pickup)may brake down due to static electricity of clothes or human body.

Some devices such as the DVD player use the optical pickup(laser diode)and the optical pickup will be damaged by

static electricity in the working environment.Proceed servicing works under the working environment where grounding

1.Put a conductive material(sheet)or iron sheet on the area where the optical pickup is placed,and ground the sheeet.

3.The flexible cable may be cut off if an excessive force is applied to it.Use caution when handling the cable.

Use due caution to electrostatic breakdown when servicing and handling the laser diode.

5.1.Grounding for electrostatic breakdown prevention

works is completed.

5.1.1. Worktable grounding

5.1.2.Human body grounding

1 Use the anti-static wrist strap to discharge the static electricity form your body.

safety_3 (1577x409x2 tiff)

5.1.3.Handing of optical pickup

1.To keep the good quality of the optical pickup maintenance parts during transportation and before installation,the both ends of the laser diode are short-circuited.After replacing the parts with new ones, remove the short circuit according to the correct procedure.(See this Technical Guide).

2.Do not use a tester to check the laser diode for the optical pickup .Failure to do so willdamage the laser diode due to the power supply in the tester.

5.2.Handing precautions for Traverse Unit (Optical Pickup)

1.Do not give a considerable shock to the traverse unit(optical pickup)as it has an extremely high-precise structure.

2.When replacing the optical pickup,install the flexible cable and cut is short land with a nipper.See the optical pickup replacement procedure in this Technical Guide.Before replacing the traverse unit,remove the short pin for preventingstatic electricity and install a new unit.Connect the connector as short times as possible.

4.The half-fixed resistor for laser power adjustment cannot be adjusted.Do not turn the resistor.

6.ASSEMBLING AND DISASSENBLING THE MECHANISM UNIT

6.1Disassembly Procedure

6.2 Terminal P.C.B.

1.Unscrew the screws.

2.Remove the solders.

3.Remove the connectors

５

6.3 Clamp Plate Unit

1.Spread the stopper with hand to silde the tabs and remove the clamp plate unit.

6.4 Tray

1.Lift the tray.

６

6.5 Traverse Block

1.Lift the traverse block while spreading the hook of the mechanical chassis chassis unit.

2.Disengage the tabs from the holes of the mechanical chassis unit.

6.6. Traverse Gear

1.Disengage the tabs from the traverse gear

2.Remove the traverse gears B and C.

７

5.6 Mechanism Unit

1.Unscrew the screws.

2.Remove the connectors.

6.7. Optical Pickup Unit

1. Unscrew the screws.

5.7 Terninal P.C.B.

2.Remove the spring holders and the springs.

3.Pull out of the drive shaft and guide shaft.

1.Unscrew the screws

2.Remove the solders.

3.Remove the connectors.

6.7.1. Precautions in optical pickup replacement

The optical pickup can be damaged by static electricity from you body.Be sure to take static electricity countermeasures

when working around the optical pickup.(Refer to the related page in this Manual about the countermeasures.

3.The use of soldering iron with anti-static feature is recommended when providing short-circuit to laser diode or when

-When using the soldering iron without anti-static feature,short-circuit the flexible cable terminal with a clip before

-After intended repair is finished.remove the solder for short-circuit of laser diode in a correct way following the

procedures described in this Manual.

short-circuiting the land.

1.Do not touch laser diode,actuator and their peripheries.

2.Do not use tester to check laser diode.(Laser diode can be damaged easily.)

removing it.

4.Solder the land on flexible cable of optical pickup unit.

6.8. Disassenbling the Middle Chassis

1.Remove the holders pins.

2.Remove the tab.

3.It lifts while pulling it in the direction of the arrow.

6.9. Disassenbling the Traverse Gear A

1.Remove the traverse gear A.

7. Electrical Confirmation

6.10. Disassembling the Sprindle Motor Unit

1.Remove the floating rubbers.

7.1. Video Output (Luminance Signal) Confirmation

DO this confirmation after replacing a P.C.B.

Measurement point

Mode Disc

Color bar 75%

Video output terminal

PLAY(Title 46):DVDT-S15 PLAY(Title 12):DVDT-S01

Measuring equipment,tools

200mV/dir,10 sec/dir

Confirmation value

1000mVp-p±30mV

Purpose:To maintain video signal output compatibility.

1.Connect the oscilloscope to the video output terminal and terminate at 75 ohms.

2.Confirm that luminance signal(Y+S)level is 1000mVp-p±30mV

DVDT-S15

DVDT-S01

7.2. Video Output (Chrominance Signal) Confirmation

Screwdriver,Oscilloscope

Do the confirmation after replacing P.C.B.

Measurement point

Mode Disc

Color bar 75%

Video output terminal

PLAY(Title 46):DVDT-S15 PLAY(Title 12):DVDT-S01

Measuring equipment,tools Confirmation value

200mV/dir,10 sec/dir

621mVp-p±30mV

Purpose:To maintain video signal output compatibility.

1.Connect the oscilloscope to the video output terminal and terminate at 75 ohme.

2.Confirm that the chrominance signal(C)level is 621 mVp-p±30mV

DVDT-S15

DVDT-S01

8. MPEG BOARD CHECK WAVEFORM

1.X204 WAVEFORM DIAGRAM

2.ZIVA-4.1 PIN.173/STRMCS WAVEFORM 

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4.VIDEO OUPUT WAVEFORM DIAGRAM

5.ZIVA-4.1PIN.172/DVDREQ WAVEFORM DIAGRAM

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