Technics SJMD-100 Service manual

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$ This document is supplementary to the

following Service Manual:

ORDER NO. AD9903069S2

Minidisc Deck

SJ-MD100

Colour

(K) ........ Black Type

Areas

(E) ........ Europe.

(EB) ...... Great Britain.

(EG)...... Germany.

Model No.

SJ-MD100

Area Code

(E) (EB) (EG)

$ Purpose

Supplement for technical information about MD.

$ Contents

1. Measuring instruments and special tools

Test Disc

Extension Cable Kit

Laser Power Meter

O ROM Part No.: RFKV0006 O ROM Part No.: RFKV0014

O Extension Cable Kit

Part No.: RFKZJMD100EK

O Laser Power Meter Model No.: LE8010

Order No.

MB9902001C2

Made by Laser Electric

2. Basic Knowledge of MD

3. Operating Procedures

4. Troubleshooting Guide for MD Servo Circuit

This service information is designed for experienced repair technicians only and is not designed for use by the general public. It does not contain warnings or cautions to advise non-technical individuals of potential dangers in attempting to service a product. Products powered by electricity should be serviced or repaired only by experienced professional technicians. Any attempt to service or repair the product or products dealt with in this service information by anyone else could result in serious injury or death.

WARNING

1999 Matsushita Electric Industrial Co., Ltd.

SJ-MD100

$ Basic Knowledge of MD

T Definition of an MD and the types of MDs

U What is an MD?

U Two types of MDs

U Playback-only MD is same

as a CD.

U Recordable MD uses

magnet optic recording.

U Playback of a Recordable

U 74-minute recording time

U Can also be used on a

computer.

Y "MD" stands for "mini disc". Y Similar to a music CD, an MD is also a small disc capable of recording and playing back digital sound.

Y There are 2 types of MDs, a optical disc for playback-only MD and a magnet optic disc for recordable MD that is

capable of both recording and playback.

Y A playback-only MD is merely a smaller-diameter version of a CD. Just like a CD, the signals are read by light

striking pits on the surface of the disc.

Y With a magnet optic disc MD(Recordable MD) that is capable of both recording and playback, recording is per-

formed by a vertical magnetization system in which a magnetic thin film on the surface of the disc is heated by a laser beam, and magnetism is applied in accordance with the data (audio signal) being recorded.

Y When a recordable MD is played back, a laser beam weaker than that used during recording strikes the disc and

is reflected back, and the reflected light is twisted (polarized) in accordance with whether the magnetized direction is upward or downward, causing the reflected light to rotate very slightly clockwise or counterclockwise. Those subtle differences in the reflected light are picked up by two light-receiving elements and detected as either a "1" or a "0" by reading whether there is electrical current or no electrical current.

Y If an MD were recorded in the same way as a CD, it would only have about 15 minutes of recording time. However,

by using a new signal compression technology called ATRAC that was specifically developed for MDs, the signals are compressed to approximately one-fifth, making it possible to record for an extended time of 74 minutes, the same as with a CD. (Blank MDs are currently marketed in two recording times, 74 minutes and 60 minutes.)

Y Although MDs were originally developed for use in recording and playing back music, in July 1993 the "MD data"

standard was established. By using an MD data+music player, MDs can be used as external memory storage media for computers, and a single MD has a storage capacity of 140 MB, equivalent to about 100 floppy discs.

T Construction of an MD

U Construction of an MD Y The playback-only MD and the recordable MD are exactly identical in size and shape.

U Materials used in an MD Y The MD disc is made of polycarbonate, the same material that is used for a CD. Polycarbonate is a type of

Construction of

magnet optic disc

MD disc form

Y The figure below is a cross-sectional diagram of an MD disc. The diameter of an MD disc is 6.4 cm, approximately

half that of a CD, and the thickness is 1.2 mm, the same as a CD. Similar to a CD, only one side of an MD disc is used to store data.

engineering plastic that is highly resistant to temperature and humidity, as well as having excellent wear and impact resistant.

Y A clamping plate is mounted in the center of the MD disc, and when the MD is loaded into a player, a magnet in the

player attracts that metal plate to secure the disc in place. If the MD disc were to be secured by clamping it from above and below similar to a CD, it would be necessary to have a hole pass through the center of the MD cartridge, which would reduce the amount of space available for attaching a label. By using this magnetic method of securing the disc, the entire front side of the MD cartridge can be used as a label area.

Y Because of the metal plate mounted at the center of the MD disc, the center of the cartridge is 2 mm thick, slightly

thicker than the rest of the cartridge.

Y To protect the MD disc from dust, fingerprints, and other things that might hinder the reading of the recorded

signals, the disc is stored inside a cartridge similar to that of a floppy disc. When the MD is loaded into a player, the shutter on the cartridge is opened and the disc is ready to be played.

Y For a recordable MD, because there is no need for a recording head and it is only necessary for a laser beam to be

directed at the underside of the disc, the shutter is located only on the back of the cartridge.

Y For a playback/record magnet optic disc MD, because it is necessary for the recording head and the laser beam to

be able to access both sides of the disc, the shutter is located on both sides (upper shell and lower shell) of the cartridge.

– 2 –

Recording on a magnet optic disc

SJ-MD100

U Can be recorded and played

back repeatedly.

U Recording principle

U Vertical magnetization

system

U Number of recordings

possible

Y By using a magnet optic disc, digital signals can be recorded and played back over and over again.

Y To record on a magnet optic disc, a laser beams momentarily heats "pin spots" on the magnetic film on the back of

the disc and a magnetic field is applied from the other side of the disc. Thus, both sides of the disc must be accessed in order to record.

Y To explain the recording principle, we will assume that the directions of the magnetism on an unrecorded disc are

all facing downward (south-north = "0 0 0 0 ..."). (Actually on an unrecorded disc the directions are random.)

Y Thus, to record the signals "1 0 1 1 0 1 0", the direction of the magnetism at the locations where "1" is to be

recorded must be changed to face upward (north-south). Because the magnetic film is strongly magnetic, once a downward-facing magnetism is recorded, it is not easy to change it to an upward-facing magnetism.

Y By directing a laser beam at the magnetic film, the temperature of the location that the laser beam strikes rises to

the Curie temperature (recordable MD; about 180pC), eliminating the magnetic force (retention force). (Because the magnetic film is strongly magnetic, similar to a permanent magnet, once it is magnetized it has a strong retention force. In order to eliminate that retention force, it is irradiated with a laser beam so that the temperature rises to the Curie temperature.)

Y After the magnetism of the specific location is eliminated, an external magnetic field with an upward direction

(north-south) is applied, thus changing the direction of the magnetism at that location to face upward (north-south).

Y Conversely, if a downward-facing (south-north) external magnetic field is applied, the direction of the magnetism at

that location is changed to face downward (south-north).

Y Then, when the disc rotates and the location which has been changed to upward-facing magnetism leaves the

laser spot, the temperature of the magnetic film drops, and the upward-facing magnetism recorded at that location is retained.

Y In this way, digital signals of "1" (upward-facing magnetism) and "0" (downward-facing magnetism) are recorded

on the tracks on the disc.

Y With a conventional magnetic recording tape, the magnetic material is magnetized parallel (horizontal) to the

surface of the tape. A magnet optic disc, however, uses a vertical magnetization system in which the magnetic poles are recorded perpendicular (vertical) to the disc surface. Because the magnetism is recorded vertically rather than horizontally, much more data can be recorded in a smaller area.

Y A magnet optic disc can be recorded more than 1 million times, so it can virtually last forever.

Magnet optic disc recording principle

Assuming that the directions of

the magnetism on the unrecorded

disc are all facing downward

(they may also all face upward).

Recorded signals.

Directions of magnetism differ

according to whether a "1" or

a "0" digital signal is recorded.

Surface of the disk is a magnetic thin film made of terbium-cobalt alloy.

Disk rotation direction

wwwwwwwwwwwwwww

Disk rotation direction

wwwqwtwwqqqwwq

00010100111001

Upword : "1" Downword : "0"

Laser spot

Disk rotation

direction

wwwwwwwwwwwwwww

Laser spot

Disk rotation

direction

wwwwwt wwwwwww

External magnetic field is applied.

Heated

Vertical magnetizationHorizontal magnetization

Only locations struck by a

powerful laser beam

(reach the Curie temperature)

lose their magnetism

retention force.

An external magnetic field is applied to the

demagnetized location,

creating upword-facing

magnetism.

– 3 –

SJ-MD100

Playback of a recordable MD

U Playback of a recordable

U Reading of magnetic signals

Y Because the signals on a magnet optic disc are recorded vertically as north-south and south-north magnetism, the

north and south magnetic poles appear on the surface of the disc's magnetic film. These signals are played back utilizing a phenomenon called the "Kerr effect" which occurs when a weak laser beam strikes the magnetic poles.

Y Light has wave vibration directions called "planes of polarization". ("Polarization" refers to a light wave which

vibrates only in a fixed direction.)

Y With normal light, because the wave vibration directions are all mixed, no planes of polarization appear. Y Because a laser beam is artificially generated light, it is possible to align the planes of polarization. Y When a laser beam strikes something that has a magnetic field, the direction of the plane of polarization of the

reflected light varies very slightly in accordance with whether the magnetism is north polarity or south polarity. When playing back a magnet optic disc MD, these slight changes in the direction of the plane of polarization are read.

Y To further explain the principle used to read the signals recorded on a magnet optic disc, first a laser beam is

directed at the disc. If the direction of the magnetism recorded on the disc is upward (north polarity), the plane of polarization of the light reflected from the disc rotates very slightly clockwise as a result of the Kerr effect. Conversely, if the direction of the magnetism is downward (south polarity), the plane of polarization rotates very slightly counterclockwise.

Y When the reflected laser light is passed through a Wollaston prism, the light is distributed to photo detector 1 if the

direction of rotation is clockwise or to photo detector 2 if the direction of rotation is counterclockwise.

Y The light striking the two light receiving elements is converted into electrical current and a subtraction is performed.

If the result of A-B is plus, a "1" is detected, and if the result of A-B is minus, a "0" is detected.

Y An MD player is compatible with both optical recording and magnetic recording, changing the reading system in

accordance with the type of disc that is loaded.

Changes in the polarization axis due to the Kerr effect

Playback of recordable MD

– 4 –

Rewriting action of a magnet optic disc

SJ-MD100

U MD rewriting process

U No need for a erasing head

Y The signals recorded on an MD are rewritten using a new process called “magnetic field modulation overwriting”*. Y In this process, a laser beam spot of about 5 mW is focused on the location on the disc to be rewritten, heating that

location to the Curie temperature (180pC) and thus canceling the magnetization.

Y At the same time, current flows to the optical pickup and to the magnetic head opposite it, between the two of which

the disc is held, thus generating a magnetic field.

Y When the disc revolves so the laser spot moves from the location to be rewritten, the temperature drops below the

Curie temperature and the magnetic field generated by the magnetic head re-magnetizes that location.

Y At this time, if the direction of the current flowing to the magnetic head is reversed in accordance with whether the

data being recorded is “1” or “0”, the direction of the magnetic field also changes between north and south, and accordingly, the direction of the magnetization of the recording film changes between upward-facing and downwardfacing. Thus, it is possible to directly magnetize the recording film on the disc in accordance with the “0” and “1” digital signals.

Y Thus, the new recording data is overwritten regardless of the direction of the previously recorded magnetization,

eliminating the need for an erasing head.

Y This process is called “magnetic field modulation overwriting”. Y Because this “magnetic field modulation overwriting” makes it possible to directly overwrite the new signals on top

of the old signals in a single process, re-recording on a MD is just as easy as with a magnetic tape, making the MD ideally suited for use in personal audio equipment.

Magnetic field modulation overwriting

*Overwrite means to write new data while erasing the old data.

– 5 –

SJ-MD100

Random access on a recordable MD

U Random access on a

playback-only MD

U Random access on a

recordable MD

U User TOC area

Y With a disc, high-speed random access is possible, something which is not possible with a tape. Y The optical pickup moves quickly in the radial direction, thus directly accessing the start of each track. Y With an optical disc, which is capable of playback only, the addresses in the TOC (table of contents) in the lead-in

area are all read beforehand in order to access the start of each track.

Y With a recordable MD, which is capable of both recording and playback, blank guide grooves, called “pre-grooves”,

are formed around the entire surface of the disc at the production stage.

Y As shown in the illustration below, the pre-grooves wobble very slightly in a regular pattern, and that curve is fine-

modulated (at intervals of 13.3 ms) to record beforehand the addresses of the continuous time data.

Y Technically speaking, the pre-grooves in the disc is not perfect spiral but is wobble with :

– a typical amplitude of 30 nm. – a spatial period of 54 to 64 ¨m.

When this wobble is locked to a frequency of 22.05 kHz, the velocity of the disc should be in the range of 1.2 to 1.4 m/s.

Y In this way, even if the MD is blank, because the addresses are already recorded around the entire circumference

of the disc, when the MD is recorded, those addresses are read in order to control the movement of the optical pickup and perform CLV control.

Y To record immediately, quick access is first performed to quickly search for an blank area on the disc, and then

recording will automatically begin. When recording is completed, that address is automatically recorded in the UTOC (user table of contents) area, so it can be read during playback for quick and easy access. This also makes it easy to edit the track number.

Y Thus, with an MD, when the recording is completed, the track data is automatically written in the U-TOC area at the

innermost part of the magnetooptic disc. The data is then read during playback for quick and easy access.

Y The addresses for the start locations of each track (track mark), and also the addresses for the end locations, are

all recorded in the U-TOC, so when editing a track all that has to be rewritten is the area address.

Y This is similar to the directory that a computer writes on a floppy disk.

Pre-grooves on a magnet optic disc

*Spindle servo control means control of the disc’s rotation speed.

– 6 –

ATRAC signal compression technology

SJ-MD100

U What does the word ATRAC

mean?

U Why is signal compression

necessary?

U Basic concept of ATRAC

Y “ATRAC” (adaptive transform acoustic coding) is the name given to the signal compression technology that is one

of the most important technologies used in the MD system. The principles of this technology are extremely complex, so here we will only explain the basic concept.

Y Simply speaking, utilizing the characteristics of the human auditory sense, the sounds that cannot be heard by the

human ear are eliminated so that only the sounds that can be heard remain, thus reducing the amount of data that must be recorded. This principle is similar to the PASC signal compression that is used for digital compact discs.

Y The amount of data that can be recorded per second (the bit rate) is 16 bits x 44,100 x 2 channels = 1,411,200 bits

per second, or approximately 1.4 megabits per second (1 megabit = 1,000 kilobits = 1 million bits).

Y However, because the diameter of an MD is only about one-half that of a CD, it only has a capacity of about 160

megabytes. In order to record the same 74 minutes of data as a CD, the bit rate of 1.4 megabits per second must be compressed to one-fifth. “A TRAC” is the signal compression technology that was developed in order to do that. (Signal compression is rather like the technology for orange juice concentrate, in which the best part of the fresh orange is concentrated for easy transportation and then reconstituted with water before drinking.)

Y The basic concept of ATRAC utilizes the characteristics of the human auditory sense. The frequency spectrum

that cannot be heard by the human ear (Fig. B) and the frequency spectrum that cannot be heard because it is masked by high-level sounds (Fig. C) are cut, and the bit rate is compressed by appropriately arranging the bits, thus making it possible to fit all of the necessary data within the capacity of the disc.

YTechnically speaking, the analog signals are converted to 44.1-kHz 16-bit digital signals, and these signals are then

processed by the ATRAC encoder. Using a maximum time of 11.6 ms as a single unit, the encoder converts the digital waveforms within each single unit into about 500 different frequency spectra and then analyzes the strength level of each frequency. Then, as shown in the figures below, utilizing the two principles of the “threshold of audibility” and the “masking effect”, only the signals actually heard by the human ear are selected and compressed to one-fifth the original volume.

YThis complex process is performed by an LSI chip called the ATRAC.

Threshold of audibility

Fig.A

Signals below the threshold of audibility are eliminated

Masking by high-level sounds

Fig.CFig.B

– 7 –

SJ-MD100

Composition of an MD system

U Development of 6 LSIs

A RF amplifier

B Servo control circuit

C Address decoder

D EFM and ACIRC encoder/

decoder

E Anti-vibration memory

controller

F Audio signal compression

encoder/decoder

U New generation LSIs

Y The figure below shows the composition of an MD system. An MD system uses six LSIs that were specifically

developed for MD. The following is a description of the functions of those six LSIs.

Y This LSI controls the laser and performs the detection processing of the servo signals and of the audio signals from

the disc needed to correct the position of the laser spot.

Y This LSI receives the laser spot position correction signals from the RF amplifier and controls the focus servo that

ensures that the laser spot is correctly focused on the disc surface and the tracking servo that controls the disc rotation direction to ensure that the pits on the disc surface are traced correctly.

Y This LSI demodulates the address signals that are recorded in the pre-group on a playback/record magnetooptic

disc MD. In addition to reading the absolute addresses, the address decoder also functions to control the rotation speed so that the servo signal is obtained at a constant linear speed at the location being read.

Y This is the main signal processing LSI. EFM is a circuit which converts 8-bit digital signals into the 14-bit format

recorded on the disc. It also performs signal processing for error correction, changing the interleaving format in order to use the ideal algorithm for MD. In addition, this LSI also performs other tasks such as encoding during recording and decoding during playback.

Y This memory controller provides a "shock-proof" memory.

Y This LSI performs the signal processing for the ATRAC compression technology that was specifically developed

for MD.

Y New genaration LSIs developed for higher performance of MD system.

There are reduced to three LSIs.

1. RF amplifire

2. 4 ch driver (servo control)

3. Signal processor

Block Diagram for playback/record MD circuit

– 8 –

SJ-MD100

$Operating Procedures

Play

P1. To read the signals recorded on the disc, the laser beam emitted by the laser diode (LD) strikes the disc and is reflected back and

detected by the photodetector (PD).

T For a pre-mastered disc, similar to a CD, the signals are recorded as pits on the surface of the disc, and the signals are

detected by the amount of light reflected when the laser beams strikes the pits.

T For a recordable disc, the signals are recorded by magnetizing the magnetic film on the surface of the disc and there is no

variation in the amount of light that is reflected, so the signals are detected using the shifting of the polarization of the reflected light due to the Kerr effect*

P2. The detected signals are input to pins 38 and 39 of the RF IC (IC1), where they are amplified and then output from pin 32.

T By observing the input signals (between pins 38 and 39) and the output signals (pin 32) on an oscilloscope, it is possible to

check the eye pattern.

P3. Error correction of the amplified signals is performed by the MD LSI (IC3: MN66616) using EFM demodulation and ACIRC*

the signals are stored in the DRAM (IC72: MNV4400). At this time, the cycle of the signals is adjusted by the LSI's clock in order to eliminate any jitter that might result from irregular revolution of the disc.

P4. The signals are sequentially taken from the DRAM (IC72) and sent back to the MD LSI (IC3), where they are ATRAC*

and then output from pin 64. All of the above steps 1 through 4 are processed on the MD servo PCB, and all of the signals are digital. P5. The digital signals output from the MD LSI are input to pin 13 of the A/D-D/A converter (IC601: AK4520) via the interface IC

(IC401: TC74HCT7007; input: pin 3; output: pin 4), where they are converted to analog signals and then output from pins 26 (left

channel) and 27 (right channel). P6. The analog-converted signals are output to LINE OUT via the buffer amp (IC711: BA4560; input: pins 5 (left channel) and 3 (right

channel); output: pins 7 (left channel) and 1 (right channel)). At the same time, they are also output to the headphone amp

(IC801: M5218; input: pins 5 (left channel) and 3 (right channel); output: pins 7 (left channel) and 1 (right channel)).

T The MD servo PCB operates at Vcc = 3.3 V, and the main PCB operates at Vcc = 5 V. For that reason, the exchange of

signals between the two PCBs is performed via an interface IC (during playback: IC401 (TC74HCT7007); during recording: IC402 (TC74HCT4050)).

T The exchange of signals between the DRAM and the MD LSI is performed using four data lines (pins 1, 2, 24, and 25 of the

DRAM and pins 43, 44, 45, and 46 of the MD LSI).

and

-decoded

Record

R1. The analog signals input from LINE IN pass through the REC LEVEL VR and are input to pins 5 (left channel) and 3 (right

channel) of the A/D-D/Aconverter (IC601) via the buffer amp (IC751: BA4560; input: pins 5 (left channel) and 3 (right channel);

output: pins 7 (left channel) and 1 (right channel)). R2. The analog signals input to the A/D-D/A converter (IC601) are converted to digital signals with a sampling frequency of fs = 44.1

kHz and then output from pin 14 to pin 65 of the MD LSI (IC3) via the interface IC (IC402: TC74HCT4050 ; input: pin 3; output: pin

4).

R3. The signals input from OPTICAL IN are input to pins 70 and 71 of the MD LSI (IC3) via the interface IC (IC401; input: pin 9; output:

pin 8). R4. The signals input to pins 70 and 71 of the MD LSI (IC3) are converted to a sampling frequency of fs = 44.1 kHz by an fs converter

inside the LSI. If the signals are already fs = 44.1 kHz, they bypass the fs converter. R5. The signals converted to fs = 44.1 kHz or the signals input to pin 65 are ATRAC-encoded and stored in the DRAM (IC72). R6. The signals are sequentially taken from the DRAM (IC72) and sent theback to the MD LSI (IC3), where they are ACIRC-processed

and EFM-modulated and then output from pin 73 to the magnetic head. R7. The magnetic disc records the signals onto the disc by magnetizing the magnetic film on the surface of the disc. During recording

the laser diode emits its laser beam in order to raise the temperature to the Curie temperature*

magnetic film. For this reason, the optical power of the laser diode is higher during recording than during playback.

T Although the disc revolves at a speed fast enough to write the signals without compression, the recording signals are

compressed in order to reduce the data volume. As a result, the signals are written intermittently rather than continuously (the recording signals are intermittently sent to the magnetic head).

that is required to magnetize the

Control

C1. Performs the necessary controls for each operation during playback and recording and for writing of the UTOC*5 at the end of

recording.

T The information written in the UTOC includes the recorded track numbers and their addresses, text data, etc.

C2. Performs the necessary displays of the text data recorded on the disc and for each operation.

The system is designed for integrated operation, so that the system control IC (IC10) on the MD servo PCB and the system

control IC (IC901) for the component system mutually exchange data (communicating).

Clock

T The controls of the playback signal, recording signals, and of the 4-channel driver IC (IC1: AN8772) all function using the clock

on the MD LSI as the master clock.

T The A/D-D/A converter (IC601) functions by using the clock signal of the MD LSI as the master clock and frequency-sampling

that signal 384 times via the clock generator (IC501: TC9246).

– 9 –

SJ-MD100

Block Diagram

Traverse motor

DISC

Spindle motor

Magnetic head

Optical pickup

0.45V P-P

0.5¨s. 50mV/DIV.

Magnetic head Drive Q10,11

RF IC IC1 AN8772

0.5¨s. 0.1V/DIV.

0.9V P-P

MD LSI

IC3 MN66616 EFM mod/demo

ATRAC encoder / decoder

Servo signal processor

DRAM(4Mbit) IC72 MNV4400

1 2 24 25

43 44 45 46

Clock

16.9334MHz

Loading motor

Detection SW

FL display

Operation SW

OPTIAL OUT

OPTIAL IN

LINE IN

4ch driver IC IC2 AN8814

Loading drive IC92 LB1830

System control IC901 M30218

Clock 10MHz

Clock

10.02MHz

Buffer AMP IC751 BA4560

System control IC10 MN101D03D

Interface IC401 TC74HTC7007

0.5¨s. 1V/DIV.

Interface IC402 TC74HC4050

0.2¨s. 2V/DIV.

20bit AD /DA converter

IC601 AK4520

5 3

4.8V

3.2V

11¨s.

4.8V

0.34¨s.

Clock generator

IC501 TC9246

LINE OUT

H.P. OUT

VOLUME CENTER

*1 Kerr effect

A phenomenon in which the polarization plane of laser light r eflected from a material shifts in one of tw o directions depending upon its “plus” or “minus” magnetic polarization.

*2 ACIRC

Add on interleave CIRC

The aim of Add-on interleave is to improve the resistivity in CD-ROM decoder from the burst error on the disc.

*3 ATRAC

The digital data compressing system developed for MiniDisc in which audio signals can be reproduced with only about 1/5 in the data normally required for high fidelity reproduction

Adaptive Transform Acoustic Cording

*4 Curie temperature

The temperature at which magnetism of a specific material dissipates. This temperature varies according to the material.

*5 UTOC

User Table Of Contents

Found only on recordable MiniDiscs, this area contains subdata (track number, etc.) which can be rewritten by the user.

1kHz, 0dB

170mV P-P

Head Phone AMP IC801 M5218

Play signal

REC signal

– 10 –

1kHz, 0dB

6.2V P-P

Buffer AMP IC711 BA4560

Clock line

3.2V P-P

1kHz, 0dB

Control line

$Troubleshooting Guide for MD Servo Circuit

Switch power ON

with no MD loaded.

SJ-MD100

Does player

enter self-check

mode? *1

*1 : See Srevice Manual page 35.

YES

Set to read power

adjustment mode. *2

*2 : See Srevice Manual page 69.

Is read power output?

YES

Can read

power be set to 600¨W

or lower using

VR1?

YES

(Continued on next page.)

CN4

5V5V5V

Is CN4 power

supply line OK?

YES

Is oscillation

signal output from IC10

pin 33?

YES

IC10 pin 33

S[T

3.3V

Check power supply

circuit on main unit.

10.02MHz

Is IC10 pin 21 "H"?

YES

Set to write power

adjustment mode. *3

*3 : See Srevice Manual page 69.

Is write power output?

YES

Adjust write power and

check ROM data laser

power and RAM data

laser power.

To "ROM/RAM Operation"

(page ?)

Faulty optical pickup

(Continued on next page.)

Faulty IC10

Is CN4 pin 14 "H"?

YES

Check reset circuit

on main unit.

– 11 –

SJ-MD100

Is output

voltage of IC1 pin 37

(TP35) approx.

1.3 V *1

YES

Is voltage

on both sides of R5

at least 0.025 V?

YES

Faulty optical pickup

See Service Manual page 27

*1:

for measurements of IC1.

Is voltage

of IC1 pin 36

2.6 V? *1

Faulty IC1

Is there

output from IC3

pin 92?

YES

Is voltage of

IC1 pin 2 (left side of R8)

approx. 1.8 V?

YES

3.3V 0V

Faulty IC9

Faulty IC3

Faulty IC1

Is voltage

of IC9 pin 3

2.6 V?

YES

Faulty L5

Is current

flowing equal to at

least 1.2 times value

indicated on pick

FPC? *2

Faulty optical pickup

*2: Indicated value: Current equal to that on both sides of R5 divided by 1 ≠

YES

Is voltage

on both sides of R5

at least 0 V?

YES

Faulty Q1

Is output of

IC3 pin 92 OK?

YES

Is voltage of

IC1 pin 2 (left side of R8)

approx. 1.9 V?

YES

Faulty optical pickup

3.3V 0V

Faulty IC3

Faulty IC1

Faulty optical pickup

– 12 –

ROM/RAM Operation

SJ-MD100

Can ROM

disc be inserted

correctly?

YES

Is disc turning?

YES

H = 3.3V L = 0V

IC10

e LOAD OPEN SW0 (S3) t LOAD PLAY SW2 (S5) y LOAD PLAY/REC SW3 (S6) q DISC-IN

IC3 pin 21

Does output

of IC3 pin 21 alternate

above and below VREF

(1.65 V)?

YES

Is voltage

output between IC2

pins 17 and 18?

YES

Disc tray

STOP/PLAY

OPEN

L H H H

Voltage alternates above and below VREF (1.65 V).

REC

H H L L

Faulty IC3

Faulty IC2

Does CN4

H L H L

pin 18 change from

"H" to "L" when disc

is inserted?

YES

Faulty loading

TRG S7

Is output of

IC10 pins 13, 15, 17,

and 18 OK?

YES

Faulty S3, S4,

S5, and S6

Is voltage

of IC10 pins 8

and 9 OK?

YES

Faulty IC10

Is voltage

output from IC92

pins 2 and 4?

Faulty spindle motor

Does optical

pickup move up

and down?

YES

(Continued on next page.)

YES

Faulty loading motor

Does output

of IC3 pin 18 alternate

above and below

VREF (1.65 V)?

YES

Is voltage

output between IC2

pins 13 and 14?

YES

Faulty IC92

IC3 pin 18

Voltage alternates above and below VREF (1.65 V).

Faulty IC3

Faulty IC2

– 13 –

Faulty optical pickup

SJ-MD100

Is TOC read

and disc data

displayed?

YES

(TP148 or IC3 pin 87)

IC1 pin 29

Is there

output from IC1

pins 11 (TP55) and

16 (TP57)? *1

YES

Can

waveform of IC1

pin 11 be adjusted so that

it is approx. symmetrical

with a level of

1.5 Vp-p? YES

Is RF

waveform output from

IC1 pin 32 (TP52)?

YES

2.6V 0V

Is there

output from IC1

pin 29 (TP148 or

IC3 pin 87)?

YES

See Service Manual page 27

*1:

for measurements of IC1.

Faulty IC1 or optical pickup

Is voltage

output from IC1

pins 38 (TP44) and

39 (TP37)?

YES

Faulty IC1

Is voltage

output from IC3

Faulty optical pickup

pin 96?

Does IC10

pin 13 change from

"H" to "L"?

YES

Faulty IC10

(Continued on next page.)

Is RF signal stable?

YES

Are

communications

between IC3 and

IC72 OK?

YES

Communications error

Faulty S4

– 14 –

YES

Faulty IC1

Faulty IC72

Faulty IC3

SJ-MD100

16.9344MHz

Is playback

possible?

Is playback sound

OK?

YES

Press eject key

and remove ROM disc.

Can RAM disc

be inserted?

YES

Is UTOC

read and disc data

displayed?

YES

Is output of

IC3 pins 61 ~ 65 OK

during playback?

YES

Faulty audio circuit

(To page 10)

After TOC is read,

does traverse move

to UTOC?

YES

Faulty IC3

See "Traverse Operation"

(next page).

10.9344MHz

3.3V 0V

3.3V

–

Play track

1 of a previously

recorded MD.

Is playback sound

OK?

YES

Insert

a recordable MD.

Is recording

possible?

YES

Faulty IC1

Is shape

of magnetic head

OK?

YES

Is there

output from CN8

TP110 and

TP111?

YES

Faulty magnetic head

of IC3 pin 73 OK?

Is output

3.3V

Operation complete.

Faulty magnetic head

– 15 –

YES

Faulty magnetic

head circuit

Faulty IC3

SJ-MD100

Traverse Operation

Traverse operation

Remains at inner track.

Is IC10 pin 12

approx. 3.3 V?

YES

Faulty traverse

detection switch S8

Remains at outer track.

Is IC10 pin 12

approx. 0 V?

Faulty (shorted) traverse

detection switch S8

YES

Is output of

IC3 pin 20 OK?

1.65V

YES

Faulty IC3

Is voltage

output between IC2

pins 15 and 16?

YES

Faulty traverse motor

Faulty IC2

– 16 –

Printed in Japan

F990406500MT/KH(D)

Technics SJMD-100 Service manual

Specifications and Main Features

Frequently Asked Questions

User Manual