Atari Sm125 User manual

--.! '

:--

..

,-,

/\. ;

:

:::

._

.

./

·~

.

..

)I~ATARf

sM12s·

High-Resolution

Monochrome Monitor

For Use

with

All ATARI

STTM

Personal

Computers

SERVICE'S

MANUAL

IiiTRODUCTIO!J

The

following

general

characteristics,

electrical

specifications

an~

safety

precautions

are

provided

for

your

information

and

use

in

maintaining

the

perfor~ance

of

the

monitor.

1.

Twelve

inch

monochro~e

display

characteristics.

AC

Input

Frequency

Response

Catliode

Ray

Tube

Scanning

Frequency

Input

Impedance/

Polarity

Resolution

GeoQetric

Distor~ion/

Line

a r i t'y·

..,

Ambient

Temperature

Humidty

C.ontrols

:

.

230V AC, 50Itz 22

i·J

a t t s

i·l

a x i mu

1:1

c r 115V

AC,

60Hz

(ju~per

wire

selectable)

Video-

bandl-ddth:

30ilHz

-3d8

at

3iJVp-p

signal

at

CRT

cathode

Rise

and

fall

time:

10nsec.:

12

inches

±

0.5

inches

diagonal

deflection

Neck

size:

Phosophor:

20mm

P193

CIE

X=

0.307

::::

Y=

0.350

±

color

0.02

coordinate

Screen

effect:

cheoical

etching

Vertical

71.41Hz

Horizontal

35.714KHz

Vertical

2K

ohr.1

I

negative

Horizontal

2!{ ohr:t I

neg<Jtive

\

640

x

t.oo

dots

t·Jithin

10;~

0°C

to

55°C

(operating)

ooc

to

65°C

(storage)

zo;~

to

90;~

r.H

A.

Internal:

Sub-Brightness

V-Linearity

.

Focus

H-Uidth

8+

12V

adjustment

li-Phase

V-Hold

V-Size

\.

Dimensions

\I

eight

.

0.

;;r.ternal:

arightness

Volume

On/Off

S~J

Approx

.

323

x

323

x

325

m~

(W

x 0 x

H)

Approx

7.SI~g

2.

Adjustments

2.1

2.2

tC'

·

'-·.

Orightness

adjustment

Procedure:

Step

1•

Step

2.

Step

3.

Step

4.

C6nnect

input

signal

cable.

P.otate

external

brightness

control

VR303

to

moximum.

notate

internal

sub-brightness

control

VR302·

to

the

threshold

of

the

raster.

Adjust

the

extern~l

brightness

VR

for

the

·

desired

brightness

level.

Vertical

size/Linearity

adjustment

\

Procedure:

Step

1 •

Step

2.

Step

3.

Step

4.

Connect

a

test

pattern

generator

Yhose

output

is

identical

to

the

signal

normally

used.

Rotate

the

vertical

size

control

VR202,

until

optimum

size

display

is

obtained.

Rotate

the

vertical

linearity

VR203,

until

extreme

top

and

cha.racters

are

equal

in

height

center

characters.

control

bottoCl

to

the

Readjust

VR202

until

the

desired

height

is

obtai·nec.l.

2

···-..

2.3

Focus

adjustment

Procedure:

The

the

near

the

o~timum

focus

of

the

monitor

is

obtained

by

adjusting

focus

control

VP.304,

for

best

focus

at

a

point

that

is

the

center

·and

approximately

1/3

down

from

the

top

of

monitor.

2.4

naster

centering

adjustment

Procedure:

Step

1•

Step

3.

Step

4.

Adjust

vertical

size

control,

VR202,

so

that

all

edges

of

the

raster

are

visibt~.~

Reposition

the

YOKE

into

the

CRT

for

best

raster

centering.

Readjust

t~e

vertical

size

to

specified

dimensions.

control,

VR2G2,

Secure

and

bond

the

YOKE

to

the

neck

of

th~

C?.T

using

hot

melt

adhesive

to

prevent

slipping

off.

3.

Safety

precautions

(\

,-·

!

l·lOT

ICE:

\

Observe

all

cautions

and

safety

located

inside

the

receiver

cabinet

and

on

the

receiver

chassis.

··

,

HARIHNG

To

prevent

fire

or

shock

haz~rd

Do

not

expose

this

a

·

ppli~nce

to

rain

or

moisture.

x-~adiation

i!arning

To

avoid

possible

ex~osure

to

X-~adiation

protective

measures

for

personnel.

Lluring

Servicing

t a

I~

e

See

service

instructions

service

adjustments.

for

specified

r e p l a c e

r.1

e n t

3

X-Radiation

parts

and

I.

O?~H1\

Tro;.j

Ti~Eo:n

1\

• S

iJ

I TCH1iIG

i·l

0 DE P0

lJ

E

~

SUPPLY

t"?~)

·,

__

1.0

Scope

The

chapter

provides

service

information

for

a

22

output

(12Vl,

single

phase

input

(120

or

240

VAC)

power

supply

CS.~.P.S.).

\:a

t t s s i ng l

.:

SHitching-mode

2.0

General

Specifications

2.1

2.2

2.3

2.4

AC

operation

voltage

I/P

: 120VAC

(90

-

13UVACl_or

24JVAC

(130

-260VAC)

~-

~

AC

operation

frequency

1/?

:

47

63

Hz

DC

0/P

regulation

DC

0/P

current

.

:

12

±

1%

VDC

for

Vo1;

±5%

for

Vo2

1 • 2

1.SA

for

Vo1;

300

rnA

for

Vo2

3.0

Theory

of

operatton

Reference

to

Figure

1,

S.H.P.S.

block

diagram

and

Finure

circ~it

diagram.

3.1

'\.

8loc~

diagram.

descripti~n-

'

The

AC

line

is

connected

to

rectifier

C:>701

-D7iJ4)

tlfrou9:1

t he l i ne f i l

t'

e

r.

( L701, C7U

·t

-C704 ) ,

\.J

h

en

· t he po

\~

e r s wi t c h

CSW700)

is

turned

on.

The

rectifier

and

DC

filter

circuit

produce

about

300

VDC

from

the'J\C

line.

After

the

input

capacitors

CC710,

C712)

are

charged,

the

start

circuit

(R705,

C716

etc)

m~ke

the

switching

circuit

(Q701)

and

the

power

transformer

CT701)

operate.

The·

power

transformer

converts

the

300

VDC

to

35.714KHz

(Horizontal

Frequency)

oscilation

square

wave

and

transfers

the

high

voltage

to

appropriate

le~el

for

the

output

voltage

which

is

produceri

by

half

wave

rectification.

and

LC

filter

CD712,

C722,

C723,

L702

etc).

The

outputs

are

12

VDC

which

are

sensed

and

regulated

by

the

paver

transformer

that

control

duty.

cycle

modulator

(ZD702,

0702-

Q704

etc)

and

driye

circuit

CC71~~

R706

etc).

4

~

......

~Q

Circuit

description

The

following

paragraphs

describe

each

block

ot

the

Block

Diagram

4.1

~ectifier

and

DC

filter

(120

VAC

operation)

4.2

4.3

ll

hen

the

operation

rectifier

300

VDC.

power

supply

is

connected

for

120

the

jumper

wire

J701

should

be

short.

(0701

-

0704)

is

connected

as

doubler

Rectifier

and

DC

filter

(240

VAC

operation)

Vi\C

That

Line

the

producting

...

.

.....

_

..

When

the

paYer

supply

is

connected

for

240

VAC,

the

jumper

wire

J701

should

be

open.

That

the

rectifier

circuit

is

used

-

as

a

bridge

rather

than

a

doubler

as

in

the

120

VAC

connection.

In

this

case,

the

rectifier

output

is

also

approximate

300

VDC.

Start

circuit,

Switching

circuit,

Power

transformer

-

When

th~

rectiiier

output

is

reaching

300

VDC,

the

start

circuit

ma~e

the

switching

circuit

operation,

then

the

power

transfori.ler

converts

300

VDC

to

35.714:~!iz

square

~iave

and

transfers

it

to

the

appropriate

Level

for

the

outp~t-

·,

\.

4.4

Duty

cycle

modJlator

~

drive

circuit

4.5

Duty

cycle

modulator

provide

a

reference

voltag~

DC

6.2V

(ZD709)

to

compare

with

output

voltage

sensor

(12V

output

voltage

adjustment

VR701)

that

control

the

feedbatk

voltage

of

the

transformer,

so

duty

cycle

modulation

and

switching

operation

will

be

comp~eted.

Isolation

transforme~

(T702)

I t ma ke s t he o s c i LLa t i

on

f r e

que

n.c

y o f t

he

s\J i t chi ng c i r cu i t

synchronize

with

the

horizontal

frequency.

5

The

video

signal

is

appliec

to

the

in;:>ut

conn;?ctor

cnjlc.

Tlle

.!C

4 0 1 S;

17

'•

06 i s ut i l i z e d a s vi d

eo

b u f f e r I f o r

me

r c i r cu i t • T

il

:!

video

amplifier

gain

is

decided

by

~407,

and

load

resisior

~415.

The

peaking

coil

L401

is

comp2nsated

for

video

frequency

response.

0403

is

a

protection

diode.

C.

'CRT CIRCUIT

'-.. ··

(

;

'.

...

··

:ligh

voltage

is

applied

tc

the

C~T

bulb

to

provide

aquada~

voltage.

"CAUTIOII".

This

is

very

high

voltage,

over

several

thousand

volts.

D

311

r e c t i f i ed t

:1

e pu l

sa

from

f l y

ba-c-k

.-

then

filtered

by

C406

to

maintain

at

a

nor~al

40

Volts

is

used

for

Q402

collector.

·

Grid

G2

is

the

acceleration

grid

and

is

maintained

at

a

normal

600

Volts

rectified

byD309

and

C31J,

u4

is

the

focus

grid.

VR304

adjust

the

focus

voltage

from

-100V

to

600V

to

improve

focus.

VE~HICAL

CIRCUIT

3.1

3.2

The

vertical

IC

TDA117u

::

i!;

a

monolithic

integr2ted

circuit

in

a

12.-

lead

quad

in-line

plastic

package.

The

functions

incorporated

are:

1)

Synchronization

circuit

2)

Oscillator

and

ramp

generator

3)

Ui g.h p o

1-1

e r g a i n a

r.1

p l i

fie

r '

\_

4)

Flyback

generator

5)

Voltage

regulator

Oscillator

circuit

The

vertical

sync

pulses

are

coupled

through

C201

to

.....

of

IC201,

VR201

adjusts

the

fr~quency

of

the

vertical

oscillator.

The

0202,

C210

is

made

up

·

of

_pump up

voltage.

3.3

Vertical

output

~he

vertical

sweep

output

is

obtained

at

4,

IC201.

R212,

C205,

R211

are

made

up

of

DC

amplifier.

R209,

R210

ar~

AC

feedback.

10

and

11

of

f e e

db

a c

!~

o f

The

vertical

size

of

adjusted

by

VR202.

·

adjusted

by

VR203.

the

raster

or

amplituda

Gf

the

sweep

is

The

linearity

of

the

vertical

sweep

is

6

i: • H0

IU

Z0iH

.'~

L CI

!'l

C

tJ

IT

The

IC301

SH74LS221

is

a

dual,

monolithic,

non-retriggerable,

high-stability

one

shot.

The

output

pulse

width,

tw

can

~e

varied

over

9

decades

of

timing

by

proper

selection

of

the

external

timing

components,

C303

and

R304,

C304

and

R303.

Pulse

widt~

is

defined

by

the

relationship:

tw

(out)

=

Cext

Rext

ln

2 =

0.7

Cext

Rext.

The

flyback

transformer

generates

the

high

voltDge

necessary

for

the

aquadag

voltage

of

the

CRT. A

secdbndary

winding

sup~lied

G1;

G2.

The

deflection

coil

current

source

is.also

obtained

from

the

out"put

of

Q302.

The

amplitude

of

tne

· p·a-Lse

is

approximat~Ly

190Vp-p,

L3Q2

adjust

horizontal

width,

and

L303

con

t r o l s t

!t

e h

or

i z

on

t a l Li ne a r i t y • C30 7 i s a

S-

s

hap

i ng

capac

i

tor

•

F.

liiGH

VOLTAGE

SUPPLY

CirlCUIT

High

voltage

is

obtained

by

rectification

of

the

high

voltase

output

of

the

flyback

transformer

T301.

This

diode

is

molded

into

_

the

transformer

housing.

\

\.

G.

AUDIO

CI~CUIT

.·,

The

ICS01

is

an

audio

amplifier.

The

power

supply

is

provided

from

6.

4

is

the

ground

Lead.

The

input

audio

signal

is

coupled

from

3

and

after

amplified

the

output

signal

is

fro~

5

to

the

speaker.

VR501

is

volume

adjustment.

CSQS

is

a

compensation

capacitor

to

avoid

from

hish

frequency

oscill~tion.

RS04,

C504

can

increase

the

high

frequency

Loading

and

keep

from

the

high-frequency

oscillation.

RS02

is

a

voltage

gain

resistor.

CS02

is

a

DC

·block

capacitor.

R503,

C507

are

•

the

impedance

matching

components

RSD1

is

the

bias

resistor.

C501,

C51G

and

C506

are

the

signal

coupling

capacitor.

CSOu

is

the

filter

capacitor.

7

I

S~~VIC~

~OT~S

..

___

,.--

l

·

.....

'

The

servic~

notes

given

here

are

to

be

utilized

in

m~intaining

monitor.

The

theory

of

operation

in

ci1apter

II

can

be

used

for

norr.~~L

o;Jer.1tion.

The

floto~

charts

in

this

chapter

should

help

isolate

~ny

given

failed

component.

1.

Circuit

tracing

2.

3.

4.

Co~ponent

reference

nu~bers

are

printer

on

top

~nd

bottom

of

the

circuit

board

to

facilitate

circuit

tracing.

In

addition,

control

names

and

boa~d

terminal

numbers

are

also

shown

and

are

referenced

on

the

chassis

schematic

diagr~m

in

this

manual.

Component

re~oval

··

-

...

. .·

~emoval

cooponents

from

the

etched

board

is

facilitated

by

the

fact

that

fhe

circuitry

appears

on

one

~ide

of

the

board

only

and

the

component

leads

are

inserted

straight

through

the

holes

and

are

not

bent

or

crimped.

The

nozzle

of

the

soldering

gun

is

inserted

directly

over

the

component

lead

and

when

sufficiently

heated,

the

solder

is

draun

3way

leaving

th~

lead

free

t~e

copper

plating.

General

troubleshooting

The

brightneis

control

should

be

adjusted

to

maxi~uu,

when

power

up

, t he e

:<

ami na t i on of t he un i t s hou l d f o l l o

1-1

t he f l o

~~

cha r t s ho

:-

1n

in

Fig.

2.

Does

the

unit

have

a

high

frequency

sound?

If

it

does,

this

means

that

high

voltage

is

being

gener~ted~

if

not

1

then

go

to

the

horizontal

diagnostic

flow

chart~

If

there

is

high

voltage

and

a

visible

raster,

then

the·proble~

may

be

diagnosed

using

the

regullr

diagnostic

flow

chart.

If

there

is

hig~

voltage

but

no

visible

raster,

there

is

probably

a

video

preble~.

Follow

the

video

diagnostic

flow

chart.

If

the

unit

is

co~~letely

dead,

one

and

both

fuses

prob~bly

bloun.

Troubleshooting

video

circuit

~ig.

3

contains

a

step-by-step

troubleshooting

guide

for

isolating

the

malfunctioing

cooponents

in

yo~r

~onochrome

diplay.

Is

there

a

video

source

connected

to

the

unit?

If

not,

check

tor

broken

connections

or

a

Loose

connector.

If

the

Haveform

of

the

emitter

of

Q4U2

exists,

see

if

tl1e

wavefor8

of

the

collector

cf

0402

exists?

If

not,

then

Q402

or

video

3+

is

de

f

ective.

If

waveforu

of

the

e~itter

of

G402

not

exist,

IC4Q•

or

G4Q1

may

be

bad

or

there

may

be

a

bad

passive

component

in

this

area.

If

G4Q2

collector

waveform

exist,

the

C2T

is

probable

bad.

·Use

safet;

precautions

to

handle

the

CUT

and

reme~~er

to

discharge

th~

uquadag

voltage

built

up

on

the

C~T.

8

~ -

·

Troubl~shooting

vertical

circuit

6.

7.

The

vertical

cirtuit

in

general

ar~

all

cont~ined

in

IC2J1.

If

the

unit

h~s

only

a

horizontal

line

or

a

very

distort~d

vertical

i

mage,

c

he

c

!~

the

de

f l e c t i

on

Y

•)

:~

E f o r a s

i1

or

t

or

I C201

lil

~

i'

::,

e

defective

or

a

pa~sive

components

is

bad.

Due

to

the

co~plete

vertical

circuit

being

contained

in

one

integrat~d

circuit~

very

feH

probler:ts

have

been

encountered

in

this

are<:~.

Troubleshooting

horizontal

circuit

The

horizontal

circuits

~re

diagnosed

using

the

floH

chart

shown

in

Fig.

4

The

methodology

used,

is

to

start

at

the

back

and

work

forward.

Is

wavefrom

of

coLLector

pu~se

0302

present?

If

wavefrorn

is

·

present

but

there

is

no

high

voltage

being

generated,

the

problem

is

usually

a

broken

printed

board

land

aroun~

_the

horizont~l

flyback

transformer.

If

waveform

is

not

present,'

is

wavefrom

of

B~S~

0302

present?

If

so,

then

0302

or

the

horizontal

flyback

is

probably

bad~

If

wavefrom

is

not

present,

then

IC301

is

pro~ably

defective.

Troubleshooting

high

voltage

circuit

If

the

horizontal

processing

and

sweep

generator

are

functioning,

the

unit

is

probably

generating

~oth

the

bootstrap

and

aquadag

voltages.

If

not~

then

check

for

broken

printed

circuit

board

Lands

or

defactive

diodes.

The

rectifier

diode

for

the

quadag

Voltage

is

not

accessible.

The

horizontal

fl~back

transformer

lilUSt

be

replaced.

'

\

B.

Mechanical

adjustments

3.1

CRT

replacement

A.

Remove

the

anode

cap

from

CRT

small

cavity

cap.

3.

Remove

th~

C~T

SOCKET

from

CRT

GASE.

c.

Loosen

the

screw

of

the

deflection

Yoke,

deflection

YQi.(E

from

CRT

COilE.

D. Remove

the

fou·r

screws.

E.

Take

off

the

CRT

ground

connector.

F.

Re~ovc

the

CRT

from

cabinet

•

9

rc;.~ove

the

Atari SM125 User manual

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