Teac Mt-20d-io User manual

TEAC

MT-2ST/20D-IO

STREAMING

CASSETTE

MAGNETIC

TAPE

UNIT

MAINTENANCE

MANUAL

TEAC

MT-2ST/20D-IO

STREAMING

CASSETTE

MAGNETIC

TAPE

UNIT

~~INTENANCE

MANUAL

TEAC

CORPORATION

fiN:

10

1(;03)4

-0/

REV.

A

CONTENTS

3.

THEORY

OF

OPERATION

3-1

Outline

of

construction

and

functions

••.••.....•..••..••••••••

3-1-1

Overall

block

diagram

......•..•.••.•.•.•..••....••....•••

3-1-2

Outline

of

mechanical

section

.••.....•.•.•.••...•••...•.•

3-2

Operation

of

data

recording/reproducing

system

(PCBA

Drive

Control)

..•••••••••.••••.•.••••.••.•••.•••••••••••

3-2-1

Read

circuit

..........................................•..

3-2-2

Write

circuit

and

erase

circuit

••••••.•••.•••.•••••••••••

3-3

Operaiton

of

tape

drive

systm

(PCBA

Drive

Control)

....••••..•.

3-3-1

Servo

circuit

•...•.••....•..•.•••.•••.•.••..••...••.•...•

3-3-2

Other

control

circuits

••..........•.....•••..•..•..••...•

3-4

"D/CAS"

Interface

control

(PCBA

Interface

Control)

...........

.

3-4-1

CPU

.•.•.•..••••..........•..••••..................•.•.•..

3-4-2

3-4-3

3-4-4

3-4-5

3-4-6

3-4-7

3-4-8

ROM

RAM

Host

interface

control

........•••..•••......••••••.....••

DMAC

Counter/timer

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

.

Write/read

control

..•.•.....••..•.•••....•......•.....••.

I/O

port

.....•••.•..•.••••..•....•••••..•••.••.•..•..••••

301

304

311

315

317

319

321

322

323

324

328

329

330

334

3-5

"SCSI"

Interface

control

(PCBA

Interface

Control).............

335

3-5-1

CPU.

. . . . . . . . . . . . . •• • • . . • . . . . . . • . . •• • • • . . . • . • • . . . . . • • . • • • . 336

3-5-2

3-5-3

3-5-4

3-5-5

3-5-6

3-5-7

3-5-8

ROM

RAM

Host

interface

control

......••.•...........•..............

DMA.C

•••••••••••••••••••••••••••••••••••••••••••••••••••••

Counter/timer

..........•............•....•.......•••.•••.

Write/read

control

..••......•...•.•.•..•••.•.••.....••.•.

I/O

port

................••.............••.........••.....

337

338

344

345

346

350

3-6

"BASIC"

Interface

control

(PCBA

Interface

Control)............

351

3-6-1

Configuration

.........••.................•.........•.....

351

3-6-2

Theory

of

operation

...•.....•..........................••

354

- i -

3-7

Functions

of

test

points,

variable

resistors

and

straps

..•....

359

3-7-1

Functions

of

test

points

.............•....•.......•......

361

3-7-2

3-7-3

Functions

of

variable

resistors

••.....••....•.........•..

Functions

of

straps

.•.....•.•..•••..••••......•........•.

377

379

4.

MAINTENANCE

4-1

Outline

of

maintenance

...••.•..•....•••........•••••.••.•••.••

4001

4-1-1

Routine

maintenance

..•.•.•.....•••......•••.•....•••.•••.

4001

4-1-2

Check

and

adjustment

.•...••....••......•..••••..••.••••••

4002

4-1-3

Maintenance

parts

....•.•..•.•........••••••.•......•...••

4004

4-1-4

Maintenance

articles

.••...•.•..•.••.....•........•..•.••.

4007

4-2

Precautions

on

maintenance

••..•••..•.•••....•...••...••••...••

4009

4-2-1

4-2-2

4-2-3

4-2-4

4-2-5

4-2-6

4-2-7

Screw

tightening

torque

and

screw

lock

(red)

.•••..••...•.

4009

Connector

handling

method

••••••..••...•.•••••.•.••••.•.•.

4010

How

to

handle

the

protector

guide

•...•••••.••...••.....•.

4015

Cable

treatment

within

chassis

.•••••..•......••.••...•.•.

4017

Initialization

of

SOA

Initialization

of

SOB

Initialization

of

SOD

4019

4021

4023

4-2-8

Initialization

of

SOE

•.....•..••.••..•••••..•.•..•.•..••.

4025

4-3

Check

and

adjustment

procedures

.......•......•.•••••...•...•..

4027

4-3-1

Positional

adjustment

of

reel

motor

(F),

(R)

Ass'y

.....••

4027

4-3-2

4-3-3

4-3-4

4-3-5

4-3-6

4-3-7

4-3-8

4-3-9

4-3-10

4-3-11

4-3-12

4-3-13

4-3-14

Height

adjustment

of

encoder

roller

Check

of

rotary

direction

of

reel

motor

•••••••.......•.••

Check

of

file

protect

sensor

....•••....•••.........•....•

Cassette

loading/unloading

check

•••....••.•........•.....

Check

of

head

shift

....•....•.....••.......••........•..•

Check

and

adjustment

of

tape

winding

.•.•......•..........

Check

and

adjustment

of

head

alignment

.....•.............

Check

of

AGe

operation

•.........•...•...............•....

Check

and

adjustment

of

BOT/EOT

hole

sensor

..•...•....•..

Check

and

adjustment

of

tape

speed

.•.....••.••...•..•..•.

Check

of

start/stop

time

........••.......••......•.•..•..

Check

of

ISV

.....•........•....•••........•..•......•....

Check

and

adjustment

of

read

preamplifier

level

......•...

-

ii

-

4029

4032

4034

4036

4037

4038

4042

4048

4050

4054

4058

4060

4062

4-3-15

4-3-16

4-3-17

4-3-18

4-3-19

4-3-20

Check

and

adjustment

of

read

level

....•...•...•......•...

Check

of

feed

through

.....•..............•••..•.•....••..

Check

of

resolution

...••.•••..••..•...•....••..•••••.•.••

Check

of

earse

level

••......••••••.••.•...••.....•..••.•.

Check

of

peak

shif

t

..•..•..••.••..•..••..••....••••...•.•

Check

of

asymmetry

..•..••......•.•.••..•..•••••....•••••.

4-3-21

Check

and

adjustment

of

VFO

operating

point

•••••••••.••••

4-3-22

Overall

check

.••••••..•....•.•....•••••........••.•..••..

4-4

Replacement

of

maintenance

parts

.••.••.•••••...•..••••...••••.

4-4-1

Replacement

of

head

Ass'y

••....•.•.••••.•...••••.•......•

4-4-2

Replacement

of

reel

motor

(F),

(R)

Ass'y

••.•..••..•..•...

4-4-3

4-4-4

4-4-5

4-4-6

4-4-7

4-4-8

4-4-9

4-4-10

4-4-11

4-4-12

Replacement

of

interrupter

C

Ass'y

Replacement

of

LED

hole

sensor

Ass'y

•••..•••••.•••••...••

Replacement

of

sensor

guide

Ass'y

..•.•••.••••••••••••.••.

Replacement

of

encoder

Ass'y,

encoder

roller

.••.•.•..••••

Replacement

of

solenoid

Ass'y

•.••...••.•.•••••.••....•••.

Replacement

of

head

base

Ass'y

•.••.•••••••••••••••.••••..

Replacement

of

PCBA

Drive

Control

•••...•.•••••.•.••.••.•.

Replacement

of

PCB

A

Interface

Control

••••.....•••..•..•.•

Replacement

of

front

bezel

.••..........••.••.•••..•......

Replacement

of

ej

ect

button

•.....•......••.....•...•..•••

5.

DRAWING

AND

PARTS

LISTS

4064

4066

4067

4069

4070

4071

4072

4074

4078

4083

4087

4090

4093

4095

4100

4105

4111

4112

4113

4115

5-1

Configuration.

••••.•

••

. • • .

.••.•

. .

••.

. . .

•••

•

••••••

.

•••••

• •

••

. • . 501

5-2

Disassembly

drawing

and

parts

lists

of

mechanical

section

.••••

506

5-2-1

Mechanical

parts

of

MTU

...••••...••.•.••.••.••••••...•...

506

5-2-2

Screws

and

washers

5-3

Parts

list

of

PCB

Ass'y

5-3-1

PCBA

Drive

Control

5-3-2

5-3-3

PCBA

Interface

Control

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

~

......•.....

In

terrupter

C

Ass'

Y

..................•.....•........•..•.

509

510

511

520

526

5-4

Circuit

diagrams

and

parts

location

diagrams

......•.........•.

528

5-4-1

Overall

circuit

diagram

......•.......••...•....•.........

529

5-4-2

PCBA

drive

control.......................................

531

5-4-3

PCBA

interface

control...................................

538

-

iii

-

Fig.

301

Fig.

302

Fig.

303

Fig.

304

Fig.

305

Fig.

306

Fig.

307

Fig.

308

Fig.

309

Fig.

310

Fig.

311

Fig.

312

Fig.

313

Fig.

314

Fig.

315

Fig.

316

Fig.

317

Fig.

318

Fig.

319

Fig.

320

Fig.

321

Fig.

322

Fig.

323

Fig.

324

Fig.

325

Fig.

326

Fig.

327

Fig.

328

Fig.

329

Fig.

330

Fig.

331

Fig.

332

FIGURES

AND

TABLES

Overall

block

diagram

•..•••••••••••••.••••••.•.••••••••.•••

301

Cassette

tape

loading/unloading

mechanism

.•••••.•••••••••••

Cassette

loading.

and

unloading

Cassette

tape

face

identifier

mechanism

••••••••••••••••••••

Read

shif

t

mechanism

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

.

Cassette

tape

loading

detection

mechanism

•••••••••.•••••.••

Write

inhibit

hole

detection

mechanism

••••••••••••.••••••••

Marker

detection

mechanism

Read

circuit

block

diagram

306

307

309

310

313

Example

of

operational

waveforms

of

read

circuit

••••••.•.••

314

Write

circuit

and

erase

circuit

block

diagram

••••••••••••••

315

Servo

circuit

block

diagram

••••••••••••••••••••••••••••••••

317

Other

control

circuits

block

diagram

•••••.•••••••••••••••••

319

Interface

bus

timing

•••••••••••.••••.••••••..••••••••••.•••

324

Host

interface

control

circuit

•••••.•••••••••••.•.•••••••••

325

Timing

in

write

operation

••••••••••••••••••.•••••••••••••••

326

Timing

in

read

operation

•••••••.•••••••••••••••••••••••••••

326

Channel

2

timing

in

write

operation

••••••••••••••••••••••••

328

Write/read

control

logic

block

diagram

•.•••••••••.•••••••.•

331

VFO

circuit

block

diagram

•..••••••••.•••.••••••••••••••••••

332

VFO

circuit

timing

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

332

Selection

operation

timing

•••••••••••••••••••.•••••••••••••

338

Command

transfer

timing

•••••••••••••••.••••••••••••••••••••

340

Read

data

transfer

timing

342

Channel

2

timing

in

write

operation

(30

ips)

•••••.••••••.••

344

Write/read

control

logic

block

diagram

•••.••..•••••••••••••

347

VFO

circuit

block

diagram

•••.•..••••••.•.•••••••.•.•.••.••.

348

VFO

circuit

timing

•••...••.••••••••.•••••••.••••.••••••...•

348

Hardware

block

diagram

......•............

..•..........

.....

352

Initial

control

•••••••••.••••••••••••••.••••.••••••••.•..•.

354

Motion

control

••.•••••..••.•••...•••••.•.••••.•••...•.•..•.

355

Tape

position

management

•.•.......•••.••.••••••••...••••.•.

356

-

iv

-

Fig.

333

Fig.

334

Fig.

335

Fig.

336

Fig.

337

Fig.

338

Fig.

339

Fig.

340

Fig.

341

Fig.

342

Fig.

343

Fig.

344

Fig.

345

Fig.

346

Fig.

347

Fig.

348

Fig.

349

Fig.

350

Fig.

351

Fig.

352

Fig.

353

Fig.

354

Fig.

355

Fig.

356

Fig.

357

Fig.

358

RDP

conversion

Cassette

load

delay

•••••..•...•.•.•.•.........•....•.••....

Tach

pulse

conversion

•.•.••.....•.•...•.....•........•.....

Positions

of

test

points,

variable

resistors

and

straps

•.••

Example

of

waveform

at

TP1

....•.....••••..•....•......•••.•

Example

of

waveform

at

TP7

•••..•.•.•••..•..•.•....•...•••••

Example

of

waveform

at

TP8

Example

of

waveform

at

TP11

Example

of

waveform

at

TP13

Example

of

waveform

at

TP14

Example

of

waveform

at

TP1

Example

of

waveform

at

TP2

Example

of

waveform

at

TP3

Example

of

waveform

at

TP4

Example

of

waveform

at

TP5

Example

of

waveform

at

TP6

Example

of

waveform

at

TP9

Example

of

waveform

at

TP1

Example

of

waveform

at

TP2

Example

of

waveform

at

TP3

Exmaple

of

waveform

at

TP4

Example

of

waveform

at

TP5

Example

of

waveform

at

TP6

Example

of

waveform

at

TP1

Example

of

waveform

at

TP2

Example

of

waveform

at

TP3

357

358

359

361

362

363

364

366

367

368

369

370

371

372

373

374

375

376

Fig.

359 Example

of

waveforms

at

TP4

and

TP5

..•.....•....•..•.•..•..

376

Fig.

401

Connector

types

........•.••................................

4011

Fig.

402

Fig.

403

Fig.

404

Fig.

405

How

to

extract

the

connector

How

to

insert

the

connectors

Sectional

view

of

housing

(black

connector)

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

.

Terminal

numbers

4012

4013

Fig.

406

Handling

methods

for

connector

J9

..................•.......

4014

- v -

Fig.

407

Fig.

408

Fig.

409

Fig.

410

Fig.

411

Fig.

412

Fig.

413

Fig.

414

Fig.

415

Fig.

416

Fig.

417

Fig.

418

Fig.

419

Fig.

420

Fig.

421

Fig.

422

Fig.

423

Fig.

424

Fig.

425

Fig.

426

Fig.

427

Fig.

428

Fig.

429

Fig.

430

Fig.

431

Fig.

432

Fig.

433

Fig.

434

Fig.

435

Fig.

436

Fig.

437

Fig.

438

Fig.

439

Fig.

440

How

to

detach

the

protector

guide

How

to

attach

the

protector

guide

4016

Cable

treatment

within

chassis

•••...••.•......•.•.........•

4018

Setting

of

SAO

MODE

switch

•.•...••.•••..••.•........•.•....

4019

Connections

of

SOA

Connections

of

SOB

Connections

of

SOD

Connections

of

SOE

4020

4022

4024

4026

Positional

adjustment

of

reel

motor

(F),

(R)

Ass'y

....••••.

4028

Set

ting

of

J l.gs

..••.•.•...•..•••.•.•.••....••••••••..••...•

4030

Height

adjustment

of

encoder

roller

..•......•••••••...••...

4031

Bonding

of

encoder

roller

4031

Check

of

rotary

direction

of

reel

motor

....••••••••.•.•.•..

4033

Mounting

of

FPT

J l.g

•.••.•••.••••.••••..••••••..•••••.•.•••.

4035

Check

of

file

protect

sensor

•.•••.•••..•.••.•......•••..••.

4035

Loading

of

mirror

cassette

•....•...••••••.•.••.••••••..••••

4040

Tape movement

check

(tape

guide)

..•.............•..••......

4041

Tape movement

check

(encoder

roller)

....•..................

4041

Burst

signal

...........•.................••.......•..•..•.•

4043

Adjusting

screws

of

head

alignment

.....................•...

4047

Check

of

AGC

operation

Check

of

AGC

operation

Hole

detection

waveform

at

TP13

Hole

detection

waveform

at

TP13

4048

4049

4051

4053

ISV

measuring

method

..••.••••••..•..•.••...••••.••••.•••.•.

4060

Measurement

of

read

preamplifier

level

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

4062

Indication

of

Error

Count

on

SOD

Replacement

of

Head

Ass'y

Replacement

of

Head

Ass'y

Replacement

of

Reel

Motor

Replacement

of

Reel

Motor

Replacement

of

interrupter

Replacement

of

interrupter

Replacement

of

interrupter

(F)

, (R)

(F),

(R)

C

Ass'y

C

ASs'y

C

Ass'y

-

vi

-

Ass'y

(1)

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

Ass'y

(2)

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

(1)

·

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

(2)

·

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

(3)

·

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

4076

4080

4082

4085

4086

4088

4089

Fig.

441

Fig.

442

Fig.

443

Fig.

444

Fig.

445

Fig.

446

Fig.

447

Fig.

448

Fig.

449

Fig.

450

Fig.

451

Fig.

452

Replacement

of

LED

hole

sensor

Ass'y

••••••••••.••••••..•.•.

Replacement

of

sensor

guide

Ass'

y

•..••••.....••.•••..••••••

Replacement

of

encoder

roller

•••..••••••••••.••••••••.•.••.

Replacement

of

encoder

Ass'y

••••••••.•••••••....•••.••.••.•

Setting

of

tilt

adjusting

jig

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

.

Tilt

adjustment

Replacement

of

solenoid

Ass'y

(1)

Replacement

of

solenoid

Ass'y

(2)

Positioning

of

head

base

Ass'y

Replacement

of

head

base

Ass'y

(1)

Replacement

of

head

base

Ass'y

(2)

Replacement

of

head

base

Ass'y

(3)

Fig.

453

Replacement

of

front

bezel

Ass'

y

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

.

4092

4094

4097

4098

4099

4102

4103

4104

4109

4110

4114

4115 '

Fig.

454

Replacement

of

eject

Button

.••••••••••••••••

'

•••••••••••••••

Fig.

501

Fig.

502

Fig.

503

Fig.

504

External

view

(1)

External

view

(2)

External

view

(3)

External

view

(4)

502

503

504

505

Fig.

505

Disassembly

drawing

of

mechanical

section

.••••••••••••••.•.

508

Fig.

506

Interrupter

C

Ass'y

527

Table

301

Write/read

signal

corresponding

table

••.••••••.•••••••••..

328

Table

302

Write/read

signal

correspoinding

table

•.•.•••••••••••••••.

344

Table

401

Table

402

Table

403

Table

404

Table

405

Table

501

Table

502

Table

503

Routine

maintenance

items

.••••••.••••••••••••••••••.••.•.•

4001

Check and

adjsutment

items

.....••••.•.••••••••••.•••.••••.

4002

Maintenance

parts

list

..•.......••••..•.•••••••..•.•.••..•

4005

Screw

tightening

torque

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

4009

Connection

of

reel

motors

••.••••.••.•••••....••.......•...

4084

Main

components

configuration

of

MTU

..••••••••••..•.••....

501

Parts

list

of

MTU

.••..•...•..•••••..•..•••......••.•......

506

List

of

screws

and

washers

....•••...•.••...•••...•..•.....

509

-

vii

-

How

to

Display

Model

Classification

-

More

than

one

model

is

available

according

to

specifications

in

the

MT-2ST

Series.

Sections

3

and

4

of

this

maintenance

manual

provide

the

descrip-

tions

in

common

to

all

the

models,

unless

otherwise

specified.

However,

partially

there

are

special

descriptions

whose

application

is

limited

only

to

particular

models

represented

by

the

following

symbols:

"90

ips"

"30

ips"

"Permalloy

head"

"Ferrite

head"

"D/CAS"

"SCSI"

"BASIC"

Applied

only

to

the

models

in

which

the

tape

speed

is

90

ips

(inch

per

second)

during

data

write/read

opera-

tion.

Applied

only

to

the

models

in

which

the

tape

speed

is

30

ips

during

data

write/read

operation.

Applied

only

to

a

model

on

which

the

parmalloy

head

is

mounted.

Applied

only

to

a

model

on

which

a

ferrite

head

is

mounted.

Applied

only

to

the

D/CAS

interface

model.

Applied

only

to

the

SCSI

interface

model.

Applied

only

to

the

BASIC

interface

model.

-

viii

-

Model

Classification

Table

Designation

Part

No. Tape

speed

Head

Interface

MT-2ST/20D-10 19305060-10 90

ips

Permalloy

head

MT-2ST/20D-11 19305060-11 30

ips

.-

D/CAS

MT-2ST/20D-12 19305060-12 90

ips

Ferrite

head

MT-2ST/20S-13 19305060-13

30

ips

MT-2ST/20S-20 19305060-20 90

ips

Permalloy

head

MT-2ST/20S-21 19305060-21

30

ips

SCSI

MT-2ST/20S-22 19305060-22 90

ips

Ferrite

head

MT-2ST/20S-23 19305060-23

30

ips

MT-2ST/20B-30 19305060-30 90

ips

Permalloy

head

MT-2ST/20B-31 19305060-31 30

ips

BASIC

MT-2ST/20B-32 19305060-32

90

ips

Ferrite

head

MT-2ST/20B-33 19305060-33 30

ips

-

ix

-

SECTION

3

THEORY

OF

OPERATION

-

300

-

\.i.l

o

....

\.i.l \.i.l

I I

........

I

....

I

PCBA

INTERFACE

CoNrROL-

- - - - - - - --l

I

r

PCBADRiVE

CoNTRoL-

- - - - -

--1

I

II

I

RD

I

~~rH~

______

~--

____

~I

____

--

__

~

I

READ

HEAD

READ

I I

CPU

8bll

I

INDICAlOR,

fRDN~

I

MOTOR.

REV

I

MOTOR

fWD

I

WRITE

a

ERASE

TRO/2

RMDDE

WD

EelK

TR

012

TR

I/~

TR

0

~y

'---------'

DSO

TSI

I I

, I

I

WRITEIREAD

1-+

CONTROL

~_f_t_..l;TS""'-O--+_---_t_-_+-__i

1/0

PORTS

1-+

CONTROL

a

SERVO

GO

fWD

HIS

lOK

I I

L-

________

J---------il------II-~R

fPT

ACK

ClD

COUNTER

TIMER

DMAC

RAM

INTERFACE

CONTROL

I

c:T'

I-'

o

n

?;'

~

9i

:t:

ONl

REQ

RST

I--f--

XfR

8=:

1

ACK

RDY

EXC

12\1

OV

I I

L-----t--t.--

--

__

J

L-...

___

....

~

DIA

I •

ov

I

L

___________________

J

POWER

(a)

"D/CAS

II

Fig.

301

Overall

Block

Diagram

VJ

o

N

READ

IIEAD

I

INDICATOR.

fRONT

PANEL

WRIT[

HUD

I------------~\

~

f-I

READ

WRITE

E\

ERASE

I

TR

0/2

I

AMOOE

I

WD

I

WEN

I

EEN

ECLK

TA

012 I

TA

Ill.

~~O

~

I

~e,

I

: :

SOLENOID,

I

!

MOT~~S"'

--

~,~"

:~:~T

~

.-1-..1.

'

1L

-v-

S :

_____

--'

I !lllAD

READ

I I

DSO

I

TSI

T50

CONTROL

I

E\

I

SERVO

I

GO

I

fWD

I

HIS

I

LOK

I

Ll

WRITE

I

: I

ERASE

HEAD

I

I I

I

~

fJ-~'~

~

,~,,~

:

- -

~

ENCOOE!i

I

~

Dp

I

LEO~~OT/EOT

T

- I I

\~

- - - - - - - - -

~

~I

CAS~!!E

LOAD

I

FI . PRnTFC I

MOTOR.

REV

I

MOTOR

fWD

I

12'1

OV

I

L-----t--~-----J

POWER

(b)

"SCSI"

Fig.

301

Overall

Block

Diagram

iPCBA

iNTERFAcE

CoNrRoL-

- - - - - - - - -l

I I

I

CPU

I

--

I

I Bbll I

I I

I

WRITE/READ

r-

I

CONTROL

I

I I

r-

DMAC

I

~

I

I I

I

----

ROM

I

I I

I

1/0

PORTS

r-

£]

I

fPT I

ACK

I

eLD

I

I I

I

or

~

o0

BSY

INTERFACE

110

~

ACK

r-

CONTROL

~

RST

COUNTER

=t:

TIMER

r-

SEL

..

POR

MSG

-+-CIO

REO

I

..

~V

I

L

___________________

J

w

o

w

READ

HEAO

I

INDICATOR,

fRON'9

WRITE

~fAO

,~-----------~,

I

I i

SOLENOID,

I

,

~ENCODER

HEAD I

IIII

MOTOR,

FWD

,...

--

~~

SHIFT

I-

I

('O~,

I

LVS

\ I

I

...

~

I I

,

r--,

I

'IIEAD

READ

I

'I'

::

,i

L

WRIT

I

L J ,---

ERASE

~EAD

, -- I I

READ

WRITE

a

ERASE

TR

0/2

RMODE

I -

'I

I

I;,

~

, I I

:~j;

r-lSENSOR

I CONTROL

a

SERVO

, MOTOR-REV

~BOT/EOT

HOLE

SOLENOID'

,

,,-

- - i

ENCODER

I

Lq-

________

C!-Cl~!

LEO

BOTIEOT

I

-T

CASSETTE

LOAD

I

fiLE

PROTECT

MOTOR

REV

I

MOTOR

FWD

I

(c)

"BASIC"

Fig.

301

Overall

Block Diagram

--GO

--L-

REV

-L-TR3

--t-

TR2

-r-

TRI

-r-

TRO

-r-

RST

-050

-r--

RDP

----UTH

-r--

UH

----

SLD

-r--

CIN

-.--USF

-TCH

--t-WDA

: I

THD

HSO

-+-WEN

-r-

EEN

I

,

L

._~~

________________

-J

3-1-2

Outline

of

mechanical

section

The

mechanical

section

of

this

MTU

(Magnetic

Tape

Unit)

consists

of

a

magnetic

head

moving

mechanism,

tape

drive

mechanism,

and

various

detection

mechanism,

mainly

the

transport

Sub

Ass'y

(sub

assembly).

Each

mechanism

is

assembled

so

as

to

keep

the

stable

quality

using

high

precision

parts,

since

compatibility

is

required

between

MTUs.

During

maintenance,

only

the

maintenance

experts

subjected

to

the

specified

maintenance

training

should

access

the

internal

mechanisms.

In

any

case,

never

give

excessive

shocks

to

the

main

unit,

but

handle

it

very

carefully.

(1)

Transport

Sub

Ass'y

The

transport

Sub

Ass'y

is

the

main

frame

to

mount

each

mechanism

or

PCB

with

the

cassette

tape

loading/unloading

mechanism

as

a

center.

It

consists

of

a

loading

base

(C)

Ass'y,

loading

base

(M)

Ass'y,

lever

base

Ass

'y

and

loading

arm

Ass

'y,

etc.

centering

around

the

chassis.

The

loading/unloading

operation

of

the

cassette

tape

is

performed

as

shown

below.

(a)

Loading

operation

When

the

cassette

tape

is

pushed

in

up

to

the

front

bezel,

the

ejector

on

the

loading

base

(C)

Ass'y

is

moved

in

the

direction

of

insertion,

and

the

cassette

tape

is

attracted

automatically

together

with

the

ejector

by

the

rotary

force

of

the

loading

arm.

When

the

stopper

of

the

ejector

is

released,

the

loading

arm

begins

to

push

the

cassette

tape

and

the

loading

base

(C)

Ass'y

at

the

right

angle

to

the

direction

of

insertion.

When

the

loading

base

(C)

ASs'y

reaches

the

predetermined

position,

the

stopper

of

the

cam

lever

roller

is

released,

and

the

reel

motor

within

the

chassis

is

lifted

together

with

the

loading

base

(M)

Ass

'y,

and

then

the

MTU

is

placed

in

the

cassette

loading

status

(Fig.

302,

303).

-

304

-

(b)

Eject

operation

\.fuen

the

ej

ect

button

located

at

the

lower

right

of

the

front

bezel,

the

loading

base

(M)

Ass'y

is

pushed

down,

and

at

the

same

time,

the

stopper

of

the

loading

base

(C)

Ass'y

is

released.

and

the

reverse

action

to

item

(a)

is

performed

continuously,

and

the

cassette

tape

gets

out

up

to

halfway

from

the

front

bezel.

and

then

the

MTU

is

placed

in

the

cassette

unloading

status

(Fig.

302.

303).

(c)

Cassette

tape

face

identifier

mechanism

If

the

cassette

tape

is

inserted

into

MTU

with

the

face

B

of

the

cassette

tape

up,

the

selector

on

the

ejector

is

turned

clockwise.

When

the

cassette

tape

is

pushed

in

further

in

such

status,

the

selector

touches

the

stopper

of

the

chassis.

and

it

is

not

able

to

insert

the

cassette

further

(Fig.

304).

-

305

-

Transport

@

@~

0 G

@

0

+

~--

~_~

___

L

__________

~_~

I I I

1

______

--

______

' I

I

'-~~~~~~-----------_/~--~,

Fig.302

Cassette

tape

loading/unloading

mechanism

Loading

base

(C)

Ass'y

Cam

lever

Loading

arm

Cassette

tape

Eject

button

Reel

motor

Ass'y

"

J \

I

I I

,..--,

c=======

(

Cassette

loading

----W.

~~~~----~==~----~=;==~~=U

status)

:::

III

t

L.':

(Unloading

status

)------

Fig.303

Cassette

loading,

and

unloading

-306 -

Chassis

Loading

base

(M)

Ass'y

o

Asymmetrical

slot

Stopper

(

Chassis

)

Selector

a

(

With

face

B

inserted

)

Fig.304

Cassette

tape

face

identifier

mechanism

-307 -

(2)

Magnetic

head

shift

mechanism

The

main

components

of

the

magnetic

head

shift

mechanism

are

a

head

base

Ass'

y

and

solenoid

Ass'

y.

A

magnetic

head

is

mounted

on

the

head

base

of

the

head

base

Ass'y.

The

head

base

is

shifted

up

and

down

(two

positions)

by

the

DC

solenoid.

The

head

base

Ass'y

contains

three

kinds

of

adjusting

screws

to

adjust

the

appropriate

head

positions

with

respect

to

the

tape

winding

position

(Fig.

305).

(3)

Tape

drive

mechanism

The

tape

drive

mechanism

consists

of

two

reel

motor

assemblies,

encoder

and

encoder

roller.

The

tape

causes

the

encoder

roller

fixed

to

the

shaft

of

encoder

to

be

rotated

by

friction.

A

feedback

signal

from

the

encoder

is

sent

to

the

reel

motor

to

apply

servo

effect

to

it

so

that

the

tape

speed

is

kept

always

constant.

(4)

Various

detection

mechanisms

(a)

Cassette

loading

detection

mechanism

This

mechanism

consists

of

a

photo

interrupter

and

a

loading

arm

(M)

to

detect

the

loading

condition

of

the

cassette

tape.

When

the

cassette

tape

is

loaded

onto

the

MTU,

the

optical

detection

path

of

the

photo

interrupter

is

interrupted

by

the

tip

of

the

loading

arm

(M).

In

this

status,'

data

can

be

written

or

read

(Fig.

306).

(b)

Write

inhibit

hole

detection

mechanism

This

mechanism

consists

of

a

photo

interrupter

and

file

protector

to

detect

the

wire

inhibit

hole

on

the

cassette

half

rear

face.

When a

cassette

tape

whose

write

inhibit

hole

is

open

is

loaded,

the

optical

detection

path

of

the

photo

interrupter

is

interrupted

by

the

file

protector.

In

this

status,

the

data

write

function

is

deactivated

and

new

write

operation

is

inhibited,

and

then

the

recorded

data

is

protected

(Fig.

307).

-

308

-

Teac MT-20D-IO User manual

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