Copal F-3503 User manual

MAINTENANCE MANUAL

Micro Flexible Disk Drives

F-3503

F-3504

COPAL

COMPANY,

LIMITED

Memory Products

Div.

•

2-16-20, Shimura, ltabashi-ku, Tokyo, JAPAN

MAINTENANCE MANUAL

· Micro Flexible Disk Drives

July,

1985

F-3503

F-3504

Rev.

1

This Maintenance Manual is subject

to

change without prior notice.

CONTENTS

SECTION

3 Explanation

of

Operation ••• •

••

•

••

•

••

•

••

•

••

••• ••• ••• ••• ••• •

••

••• ••• ••• •

••

•

••

•

••

•

••

3CX)

3-1 Outline

of

Construction

and

Functions

3-1-1 Overall block diagram

3-1-2 Outline

of

mechanical

section

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

3-2

Circuit

Operation

3-2-1 Read/Write

circuit

3-2-2 Control

circuit

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

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

3-2-3 Servo

circuit

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

3-3 Functions

of

Iest

Points

and Potentiometers

3-3-1

3-3-2

Test

point

functions

Potentiometer functions

301

302

305

310

313

314

315

318

SECTION

4 Explanation

of

Maintenance •

••

•••

•

••

•

••

•••

•

••

••• ••• •••

•••

••• •••

•

••

•

••

•

••

•

••

400

4-1 Maintenance Outline

4-1-1

4-1-2

4-1-3

4-1-4

Periodic maintenance

Inspection and adjustment

Replacement

of

maintenance

parts

Tools required

for

maintenance

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

4-2 Maintenance Cautions

4-2-1

Screw

torque and

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

screw lock

4-2-2

4-2-3

4-2-4

Handling

the

connectors·······························································

Cable treatment

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

Others

4-3 Periodic Maintenance

4-3-1

4-3-2 Cleaning

the

magnetic beads with a cleaning

disk

Cleaning

the

magnetic beads

by

direct

procedure

(single

side

type)

401

402

403

406

407

408

410

413

415

416

4-4

Inspection

and Adjustment Methods ...

···

······

...

······

......

···

·..

···

417

4-4-1

File

protect

sensor

inspection

...

···

······

···

············

···

······

···

······

417

4-4-2

Disk

rotation

speed

inspection

and

adjustment

············

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

418

4-4-3

Head

touch

inspection

and

adjustment

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

···

············

... 419

4-4-4

Asymmetry

inspection

422

4-4-5

Read

level

inspection

···

·········

···

······

···············

······

···

...

······

··· 424

4-4-6

Resolution

inspection

···

······

···

·········

···

···············

··· 426

4-4-

7

Track

alignment

inspection

and

adjustment

····

.....

····•· ···

·········

....

·· 428

4-4-8

Track

00

sensor

inspection

and

adjustment

......

···

····•·

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

······

433

4-4-9

Track

00

stopper

inspection

and

adjustment

······

···

···...

···

·········

435

4-4-10

Index

burst

timing

inspection

and

adjustment

···············

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

436

4-5

How

to

Replace

Parts

·········

···

······

···

·········

···

············

···

··· ······

···

438

4-5-1

Head

carriage

assembly

replacement

......

······

···

•·•

···

···...

··· 438

4-5-2

Stepping

motor and

steel

belt

replacement

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

···

······

...

442

4-5-3

Disk

Drive

motor

(spindle

motor)

replacement

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

444

4-5-4

Track

00

sensor

replacement

······

···

...

············

······

...······

......

···

......

445

4-5-5

Hain

PWB

assembly replacement

···

······

···

······

···

446

4-5-6

Index

sensor

PWB

assembly

replacement

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

···

...···

...

447

4-5-7

Head pad

replacement

(single

side

type)

······

......

···

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

···

448

4-5-8

Front

bezel

replacerne.nt

···

······

···

·········

···

·········

······

4.5()

4-5-9

Front door replacetnent

···

······

···

·········

···

·········

···

451

4-5-10

Eject

bu.tton

replace111e:nt

·········

···

···············

···

······

···

452

SECT

I

ON

S Drawings and

Parts

Lists

......

···

·

.....

······

...······

.........

·

.....

···

....

··

.5aJ

5-1

Construction

.5()1

5-2

Structural

Parts

Exploded Drawing,

Parts

List

...

···

......

·········

···

···...

506

5-2-1

Floppy Disk Drive

chassis

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

,.

.........

506

5-2-

2 Sc!rews and washers ····

··

··············· ····················· ······ ············ ······

51:9

5-3

PWB

Assembly

Parts

& Drawing

No.

List

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

510

5-3-1

Hain

PWB

assembly

···

······

·········

···

·········

······

···

···············

510

5-4

Circuit

Diagram and

Actual

Wiring Diagram

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

,

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

515

SECTION

3

Explanation of Operation

-300-

3-1 Outline of Construction

and

Functions

3-1-1 Overall block diagram

READ

DATA

WRITE

GATE--

SIDE

ONE_

SELECT

WRITE

DATA

.

·-

DRIVE

SELECT

0-3

HOIOR

ON

STEP

DIRECTION

SELECT

TRACK

00

INDEX

READY

WRITE

PROTECT

-

+12V,+SV-

OV

Read/

Write

circuit

-----

Control

circuit

J--------'

Servo

File

protect

sensor

Disk-in sensor

Disk

Hagnetic

head

Track

00

sensor

Disk Drive

110tor

(spindle motor)

Stepping motor

Fig.

301

Overall Block Diagram

-301-

3-1-2

Outline

of

mechanical

section

Ihe

mechanical

section

of

this

Floppy Disk Drive

is

assembled

care-

fully

and

accurately

with

precision

parts

because

the

recording

medium

is

soft

based on

disk

and

polyethylene

film,

an

arbitrary

change

is

available

and an

interchangeability

of

data

is

required

between Floppy

Disk Drives. Therefore,

the

mechanism

interior

must

not

be tampered with

by

other

than personnel

trained

for

specialized

maintenance.

And

the

instrument must

not

of

subjected

to

excessive shock nor dropped, and

must be handled

carefully.

Ihe

mechanical

section

is

centered

on

the

frame and

consists

of

disk

chucking

mechanism

and

disk

eject

mechanism,

disk

rotation

mechanism,

magnetic heads and

carriage,

head seek mechanism,

different

detect

me-

chanisms,

etc.

(1)

Frame

Constitutes

a framework

to

mount

on

each

mechanism

and

PWB.

Con-

sists

of

an

iron

chassis.

Considerations have been given

to

suffici-

ently

maintain

stable

the

reliability

of

Floppy Disk Drive concern-

ing

the

mechanical

strength,

accuracy,

resistance

to

weathering

expansion

rate

and

all

other

respects.

(2) Disk chucking

mechanism

and

eject

mechanism

Ihe

disk

chucking

mechanism

and

eject

mechanism

consist

of

trigger

lever,

eject

lever,

etc.

centered

on

the

disk

housing which

serves

as

a guide

for

mounting a

disk

on

the

spindle.

On

the

disk

chucking mechanism,

inserting

a

disk

disengages

the

trigger

lever

claw,

the

disk

moves

downward

along

with

the

disk

housing, and

the

disk

center

is

chucked

to

a

correct

position.

Ihe

eject

mechanism

is

designed

in

such a manner

that

pushing

the

eject

button

causes

the

eject

lever

to

push up

the

disk

housing,

whereby

the

pushup

action

lever

pushes

out

the

disk.

(3) Disk

rotating

mechanism

The

disk

rotating

mechanism

consists

of

Disk Drive motor

including

the

spindle.

The Disk

Drive

motor

is

an

outer

rotor

type

DC

brushless

motor

directly

coupled with a

spindle,

and has a long

life

of

20,CXX>

hours

or

more

in

continuous

rotation.

The

rotation

speed

is

300rpm. A

servosystem works

to

maintain

the

speed

constant

regao:fless

of

vari-

ations

of

load an ambient temperature through feedback

signals

from

the

AC

tachometer

built

in

the

motor.

-302-

(4) Magnetic heads and

carriage

Read/Write

core

Read/Write gap

Bulk head

Fig.

302

Read/Write

core

---...

Direction

of

disk

rotation

Erase

core

Read/Write gap

Laminated head

External Appearance

of

Magnetic

Head

Core

Erase

core

On

the

single

side

Floppy Disk Drive (F-3503),

the

magnetic head

is

a button type and

is

mounted

on

the

carriage

so

it

touches

the

head

window

section

of

the

disk

side

0 (bottom

when

Floppy Disk

Drive

is

placed

horizontal).

On

the

double

side

type

Floppy Disk

Drive

(F-3504), on

the

other

hand, both

side

0 and 1 heads

are

a

special

flat

type

supported

by

a gimbal

structure.

The

two

heads

are

mounted

on

a

single

carriage

so they pinch

the

respective

disks

from

outside.

Each

of

the

heads

is

designed so

that

the

head

surface

minimizes

the

wear

of

disk

and

that

a

single

reproduced from

the

disk

is

a

maximum,

and

the

head

itself

is

along

life

type

free

from

excessive

wear.

As

shown

in

Fig.302,

this

Froppy Disk Drive adopts heads hav-

ing

a bulk

or

laminated

core

structure.

The

head

center

consists

of

a Read/Write gap used

for

any

of

re-

cording

and

playback

of

data,

and

two

erase

gaps

for

deleting

(tunnel

erase)

the

edge

of

recording

track

immediately

after

record-

ing.

The

two

heads having

different

core

structures

have

the

same

func-

tion.

It

is

possible

to

provide a

perfect

interchangeability

between

data

recorded

on

the

disk.

The

magnetic heads and

carriage

where

the

heads

are

mounted

are

a

vital

part

of

Floppy Disk Drive and assem-

bled

particularly

accurately.·

(5)

Head

seek

mechanism

The

head seek mechanism

consists

of

steel

band, guide

shaft

and

carriage,

centered

on

a

stepping

motor provided with a capstan

(pul-

ley).

The

carriage

slides

on two guide

shafts

and

is

connected

through a

steel

belt

with

the

capstan

of

stepping

motor.

The

stepping

motor employed

is

a

flat

four-phase

type

and

turns

1

step

(corresponds

to

l.B·

)

for

a head

movement

of

1

track.

The

shaft-to-disk

axis

parallelism

and

distance

and

shaft

and

capstan

dimensions

are

accurate.

The

expansion

by

temperature has

sufficiently

been

studied

along with expansion

of

the

chassis,

steel

band,

carriage,

etc.

so

they

are

offset

with expansion

of

the

disk

itself.

(6)

Different

detect

mechanisms

(a)

File

protect

detection

mechanism

Consists

of

sensor

and

sensor

lever

for

detecting

a presence

of

a

write

protector

detect

hole

of

the

protective

hard

case.

The

write

circuit

operation

is

blocked

if

the

sensor

is

not

intercepted

by

the

sensor

lever

when

mounting a

disk

whose

detect

hole

is

open.

(b) Track 00

detect

mechanism

Consists

of

a

sensor

for

detecting

the

outermost

peripheral

position

(track

00)

of

the

head

carriage

and

track

00

stopper.

The

disk

is

used

within

the

track

00.

Even

if

the

head

moves

outside

on

account

of

shock,

etc.,

the

head

carriage

hits

to

track

00

stopper

and

the

head

is

prevented from

moving

outside

the

range where a

self

return

is

available

by

turning

on

power.

Designing

is

made

so

as

to

ignore

a

stepout

instruction

from

the

track

00

position

by

judgement

of

the

Floppy Disk Drive

internal

circuit.

If

a

stepin

instruction

is

inputted

further

from

the

innermost

track,

the

head

further

moves

inside

with an enough allowance

to

prevent

the

head from touching

the

head

window

edge.

In

order

to

perform a

track

recalibrate

action

(track

00

return)

from

this

position,

it

is

necessary

to

input

a

stepout

instruction

several

steps

in

excess

of

the

maximum

number

of

tracks.

(c) Index

detect

mechanism

Consists

of

a

reflector

mounted on

the

rotor

of

the

spindle

motor (Drive Disk motor) and a

sensor

arranged

on

the

motor

•

side.

The

motor

rotation

turns

the

reflector,

which

reflects

the

beam

coming from

the

sensor,

and

the

reflected

beam

is

detected

by

the

sensor.

-304-

3-2

Circuit Operation

The

circuitry

consists

of

Read/Write

circuit,

control

circuit

and servo

circuit,

and they

are

mounted

on

the

ma.in

PWB

assembly.

3-2-1 Read/Write

circuit

The

Read/Write

circuit

consists

of

read

section,

write

section,

low

voltage

detect

section,

etc.

and

is

housed

in

1-chiop

bipolar

IC along

with

the

major

part

of

the

control

circuit.

Fig.303

shows

its

block

diagram.

-305-

I

w

0

en

I

Read/Write

coil

Erase

coil

TP8

SIDE

ONE

1

WRITE:

WRITE!

Killed

erase·

SELECY:

GATE

DATA;

r

SIDE

0

SIDE

1

IP6

Erase

gate

,------

Common

driver

Hatrix

Erase

1

driver

I

--------------------,

·Control

Write

amp

current

sync

Low

voltage

detect

circuit

lime

domain

filter

Read

data

pulse

generation

--------

Driver

__

__.

Diff

eren-

tial

amp

1------

READ

DAIA

L--------------

Fig. 303

IP2

!Pl

Low

pass

filter

IP4

TPS

Read/Write

Circuit

Block Diagram

Magnetization

of

disk

_-_

....

I

__

__._

__

___..

__

__,l_-_l._-_.._l

_-

__

_.I_-_

Pre-amp

output

Pre-amp

output

Differential

amp

output

Differential

amp

output

Fig. 304 Typicql

Read

Circuit Operating Waveforms

(1)

Read

section

The

read

section

consists

of

pre-amp, low-pass

filter,

derivative

amp,

time

domain

filter

and read

data

pulse

generator

circuit

(out-

put

driver).

At

read time, a small

voltage

induced on

the

Read/Write head

is

boosted

by

the

differential

pre-amp,

is

deprived

of

noise

and

other

undesired components

by

the

low-pass

filter,

and

is

delivered

to

the

derivative

amp.

The

derivative

amp

shifts

the

peak

position

of

the

reproduced

signal

to

the

zero

cross

position

and, by optimumly

ap-

plying

a

correction

to

off

set

the

difference

in

the

frequency

com-

ponent,

further

amplifies

the

signal.

Its

output

is

converted

into

a

square

wave

by

the

peak

detector

consisting

of

a comparator,

is

de-

prived

of

undesirable

influence

by

saddle

produced

at

a reproduc-

tion

of

the

low

frequency

section

by

the

time domain

filter,

and

is

outputted

from

the

Floppy Disk Drive

through

the

read

data

pulse

generator

and

output

driver.

(2) Write

section

The

write

section

consists

of

control,

write

amp

current

sync,

common

driver,

erase

driver

and

other

circuits.

The

control

circuit

turns

on

when

the

file

protect

sensor

detects

-307-

the

disk

jacket

side

noch

(write

enable

status)

and

WRITE

GATE

input

signal

is

TRUE,

or

when

the

erase

gate

signal

produced

by

specified

timing

based on

WRITE

GATE

signal

is

TRUE,

and

supplies

power

of

about

lOV

to

the

center

tap

of

the

Read/Write head. These power

gate-on

conditions

are

generated

by

the

control

circuit.

·

The

WRITE

DATA

pulse

train

from

outside

is

latched

by

the

data

latch

and,

by

turning

on

an

off

two

write

drivers

alternately,

an

appropriate

recording

current

is

applied

to

the

Read/Write head.

The

erase

head

is

located

0.7nun

behind

the

Read/Write gap

in

such

a manner

that

it

is

placed

in

between.

The

erase

gate

signal

is

de-

layed

by

the

amount

of

0.7nun

offset

of

WRITE

GATE

input

signal.

The

erase

driver

operates

so

as

to

cover

the

recording

area

by

the

Read/

Write head. Delay

timing

is

produced

by

the

Wri~e/Erage

gate

of

the

control

circuit.

So

long

as

the

write

driver

is

in

an

operating

status,

READ

DATA

pulse

output

is

blocked.

WRITE

GATE

input

signal

Erase

on

delay

(Internal)

WRITE

GATE

.

/"/.

/

I'.///'/./

//;~/.1//~'>/'//

//'/..

Write

driver

area

of

operation

,...._

__

---t-

_

Erase

gate

signal

__

__,I

Erase

driver

area

of

operation

1 ·

~

1

r

SIDE

ONE

SELECT

-,-------

--\1---------r-

__j

__________

-if-·------_j__

WRITE

DATA

input

signal

Data

latch

output

Write

driver

output

Write

current

Hagnetization

of

disk

01-1-

I-I

-

l-1-1-1-l-l-l;~:\;(~;/>:i'.'.>

\

Erase

off

delay

Fig. 305 Typical Write Circuit Operating

Waveforms

(3)

Low

voltage

detect

circuit

The

low

voltage

detect

circuit

is

intended

for

avoiding an

erratic

operation

due

to

the

Floppy Disk Drive

internal

circuits

when

the

-308-

detect

circuit

covers

the

write

circuit

and

function

block, and

pre-

vents

the

write

driver

and

erase

driver

from

operating

erratically

when

+SV

is

unstable

and

the

Floppy Disk Drive

internal

logics

do

not

function

properly

and

when

+12V

is

unstable

and

writing

is

not

warranted.

3-2-2

Control

circuit

The

control

circuit

consists

roughly

of

three

circuits:

Write/Erase

gate

for

determining

the

timing

for

applying a

current

to

the

head

when

recording,

spindle.motor

gate

for

determining

the

spindle

motor

turning

conditions

and

other

gates;

index

detector,

track

00

detector,

file

pro-

tect

detector,

ready

detect

circuit

and

other

detect

circuits;

and

step-

ping motor

control

circuit,

and

is

mainly

accommodated

in

1-chip

bipolar

IC.

Each

detector

(phototransistor)

is

mounted

on

the

track

00

sensor

PWB

assembly, and

all

other

control

circuits

are

mounted

on

the

sensor

PWB

assembly, index

PWB

assembly and main

PWB

assembly.

The

drive

select

gate

is

a

circuit

consisting

of.straps

(short

bars)

for

transmitting

the

select

status

to

the

control

LSI

inside~

and

selecting

the

lighting

conditions

of

the

front

bezel

display.

The

Write/Erase

gate

judges

the

conditions

where

writing

is

available

by

Floppy Disk Drive, and

issues

a

write

instruction

(write

gate

and

erase

gate

signal)

to

the

write

circuit

and,

by

the

internal

one-shot

11JUltivibrator,

the

specified

delay

time

is

provided

for

the

erase

gate

signal.

The

ready

detect

circuit

outputs

a ready

signal

about 1 second

after

MOTOR

ON

signal

and

DISK

IN

sensor

signal

are

inputted.

The

stepping

motor

control

circuit

consists

of

direction,

shift

register,

overdrive

single

shot,

etc.

The

direction

is

a

circuit

for

sampling

the

head moving

direction

specified

by

DIRECIION

SELECI

signal

every

time

STEP

pulse

is

inputted.

By

the

shift

register,

the

direction

is

converted

into

a

drive

signal

appropriate

for

the

bipolar

2-phase

exciter

of

the

4-phase

stepping

motor and

is

applied

to

the

stepping

motor.

The

overdrive

single

shot

turns

on

the

overdrive

circuit

for

a

speci-

fied

time

(approx. 70msec). During

this

while,

about

lOV

is

applied

accross

the

stepping

motor

coil

so

as

to

obtain

a necessary

torque

suf-

ficiently

in

seek and

settling

operation.

After

end

of

settling,

only

+SV

is

applied

to

the

stepping motor

coil

and unnecessary power

loss

is

not

caused except

that

a torque

is

kept

enough

to

hold

the

head

stop

position.

Thus,

heating

from

the

motor

is

suppressed

low

and

the

power

consumption

of

the

stepping

motor

is

reduced

to

a

low

level

at

seek

stop

time.

-310-

DRIVE

SELECT

0-3

WRITE

GATE

DIRECTION

SELE

CI

STEP

HOIOR

ON

r--

--------

--

-----

-----,

I Control

IC

I

I I

I Drive

select

l

gate

r--., I

I Output I

I I

I 1

I

driver

I I

I--<

I

Indicator

gate

I

.....,

I

I I

I

r--

________

.J

I I

I

J Write/Erase

gate

1--c l

I I

I I Over-drive

I

I I J

circuit

l Stepping motor I

I

control

circuit

H I

I I

I I Stepping motor

I I

L-----------

_J

-

t--

driver

.

I

RACK

00

IN

DEX

WR

PR

IIE

OIECT

R

EADY

Fr

ont

bezel

indicator

ad/Write

Re

circuit

Stepping

motor

~

Ready

circuit

Disk Dri

ve motor

e motor)

rvo

circuit

(spindl

se

File

protect

detector

Disk-in

detector

Index

detector

17

Irack

00

detector

•

Fig. 306

Control

Circuit

Block Diagram

-311-

DIRECTION

SELECT

input

signal

STEP

input

signal

·Step

out

Step

in

Direction

latch

output

--LL-..J.----1----1----~

Over-drive

circuit

input

_

177J7J7.

_,,,..._~----+---+-----f-+--+--~'r-S'-'-LLl.J

Motor

driver

input

PHASE

A

PHASE

B

-

PHASE

A

-

PHASE

B

Stops

on

even

numbered

track

Stops on odd

numbered

track

s

Fig.

307

Typical Stepping Motor Control Circuit Operation

Waveforms

-312-

3-2-3

Servo

circuit

The

servo

circuit

keeps

constant

the

spindle

motor

speed,

and

is

mounted

on

the

main

PWB

assembly

separate

from

the

spindle

motor.

Start

and

stop

of

the

spindle

motor (Disk Drive motor)

are

control1ed

by

MOTOR

ON

signal

by

way

of

the

control

circuit.

The

motor

is

a 2-phase

excitation

long-life

brushless

motor, and

is

driven

by

2-phase

driver

IC intended

for

this

purpo~e.

The

2-phase

ener-

gization

and

excitation

direction

is

changed over

by

signals

from Hall

generator

mounted

on

PWB

in

the

rotor

in

such a manner

that

the

drive

coils

and

excitation

direction

are

successively

changed

in

the

specified

turning

direction.

The

rotation

speed

is

kept

at

a

desired

level

stably

and

accurately

by

applying

to

the

drive

voltage

control

section

of

the

driver

the

feedback

signal

from

the

AC

tachometer

pattern

etched

on

PWB

of

the

rotor

periphery

which

is

subjected

to

F-V

conversion (frequency-

voltage

conversion)by

another

servo

IC.

-313-

3-3 Functions of Test Points

and

Potentiometers

Fig.308

shows

the

arrangement

of

the

test

points

and

potentiometers.

VR2

~rotation

speed

control.

potentio

..

ter)

tP

1

2

3:

GND

(OV)

4

5

6

7

8

(asymmetry

adjust

potentiometer)

Fig.

308

Arrangement

of

Test Points

and

Potentiometers

-314-

3-3-1

Test

point

functions

On

the

main

PWB

assembly, seven

test

points

(including

1 ground)

are

provided

for

observing

the

waveform

necessary

when

adjusting

or

inspect-

ing

the

Floppy Disk Drive.

(1)

TPl

and

TP2

(pre-amp)

Test

points

for

observing

the

Read/Write

amp

output.

The pre-amp

has

two

outputs

of

several

ten

to

several

hundred

mVp-p

of

1so·

off

phase

(reverse

phase),

and

they

are

observed

at

TPl

and

TP2,

respectively.

For an

accurate

waveform

observation,

one

channel must

be

added

in

an

invert

mode,

and a

single

waveform must

be observed with TPl and

TP2

by

means

of

2-chanpel

oscilloscope.

As

an

oscilloscope

ground,

use

the

nearby IP3(0V)

test

point.

TPl

and

TP2

are

used

for

checking

different

characteristics

of

the

Read/Write head and

also

for

checking

or

adjusting

mechanical

factors

of

the

bead

seek

mechanism and magnetic head such

as

track

alignment.

Pre-amp

Fig. 309 Typical

Waveform

(2)

TP3

(OV)

Used

as

ground

for

measuring

instrument.

When

an

alligator

clip

is

used,

there

is

a

fear

of

short-circuiting

with

an

adjacent

test

point.

Therefore,

connect

carefully.

(3)

TP4

and

TPS

(filter

out)

Test

points

for

observing

the

low-pass

filter

output.

The

same

as

the

pre-amp, two

outputs

of

several

hundred

to

several

rnVp-p

are

present

and can

be

observed

at

TP4

and

TPS,

respectively.

For an

accurate

observation,

use

2-cbannel

oscilloscope.

Set

one

channel

to

an

irivert

mode

and add

the

signals.

Observe

the

waveform

between

TP4

and

TPS

as

a

set.

As

an

oscilloscope

ground,

use

the

nearby

TP3(0V)

test

point.

-315-

Copal F-3503 User manual

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