Sharp MZ-80A Service Manual

,

SHARP

PDSM9S1

01

O-MZ

Personal Computer

Z-BOA

IFEATURESI

• The

MZ-80A

is a full

-fledged personal

microcomputer

equipped

with

B·blt microprocessor

(l-80)

and it can

meet

a variety

of

applications like hobbies, educations, office works, controls (of

apparatus in every industrial fieldl,

etc

.

• It

is a compact

desk-top

type,

itself a

simp

lified

unit

including CPU

board,

CRT

display,

cassette

tape

recorder

and

keyboard

all

together

.

•

The

keyboard touch

will

satisfy professional operators, and numerical

input

keys are provided.

• Speaker (3 octaves)

and

clock function are built in.

• A video

RAM

of

2K

bytes

is

provided

to

facilitate

edition

aided

by

CAT

display .

•

• Memory extensions

is

allowed

up

to

4BK bytes in the board.

• Four types of I/O cards for peripherals such as a floppy disk and printer

ean

be

added

by optional

extension

units

.

•

SHARP CORPORATION

,

Contents-------------

Specifications

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

1

Trouble shooting guide

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

: . . . . . . • . . . . • . .

..

3

CPU

board section

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

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

..

4

Display section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

..

11

Cassette tape recorder section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

..

15

Power

supply

section.

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

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

'.

. . . . . . . . . .

..

19

Circuit diagram and printed wiring board

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

21

Disassembled

view

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

35

Packing method

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

,

39

Replacement parts

list.

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

..

40

Caution in Service

it

Maintain the safety and protecting ability

of

the apparatus

after

serVice.

it

High

voltage shall

not

be rised

to

excess voltage so as

to

prevent

this apparatus from the extra X-ray radiation.

I

• General

CPU

Z-80

Clock

function

Built in

Memory

ROM; 4K bytes (Monitor) Music

function

Built

in

ROM; 2K bytes (character generator)

Editor

Cursor

control;

"up",

"down",

RAM; 32K bytes (dynamic

RAM)

function

"right",

"left",

Memory extension; 48K bytes

"home",

"cleary

home"

(max.)

Edit

key, Delete key

RAM; 2K bytes (video RAM)

Roll

up

and

roll

down

Display

9"

CRT (green display)

Power supply

AC

220V

± 10%,

50

Hz

8 x 8

dot

matrix.

AC

240V ± 10%,50

Hz

Characters;

1000

(40 characters x

25

lines)

Power

Cassette

Standard

audio

cassette tape

consumption

Approx.36W

Data transfer speed;

1200

bits/sec.

Temperature

Operating

temp.;

O°C

to

35°C

Data transfer system; SHARP

PWM

Storage

temp.;

_15°C

to

60°C

Sound

output

400mW (max.)

Humidity Lower

than

80° during operation

Keys layout Number;

73

keys

Weight

Approx. 10kg

ASCII

standard

Width;

440mm

(alphabet capital letter, figures),

Dimensions

Depth;

480mm

Small letter, Graphic, 10 Numerical

Height;

260mm

•

CPU

Board Section

CPU

Z·80; 1 pc

Programmable

8253

1

pc

ROM

Monitor; 1 pc (4K bytes)

counter

Character generator; 1 pc

(2K

bytes)

Programmable

RAM

Standard;

peripheral

8255

1 pc

16K

dynamic

RAM; 16 pcs.

interface

(32K bytes)

Video RAM; 1 pc

(2K

bytes)

• Power

Supply

Section

Input

AC 220V ±10%, 50Hz AC

240V ±10%,

50Hz

Output

DC12V DC5V DC-5V

-1-

• Display Section

I. General specifications

11.

Electrical specifications

Size

9"

Video

output

4OVp-p standard (35Vp-p limit)

Frequency

60Hz (vertical), 15.7SkHz (horizontal)

Resolution

Horizontal

These patterns

of

the

11

left

in

the

center

ofthe

picture must be clear.

Power

source

DC

12V,

1.lA

±10%

Non-linearity

Horizontal;

±8%

(±14% max.)

distortion

Vertical;

±8%

(±12% max.)

Picture tube

Cl0M36P31

or

2728B31;

Geometrical Pincushion dist.;

1%

(2%

max.)

9"90°

deflection

explosion proof type

distortion Barrel dist.; 1

%

(2%

max.)

Trapezoidal dist.;

1%

(2%

max.)

Heater; 12V. 7SmA

Parallelogram dist.; 10 (2.So max.)

IC

2 pes.

High

voltage

Zero beam; 11.0kV

(10.0kV, min.,

Transistor 7 pes.

12.0kV, max.)

Diode 13 pes.

Power supply

DC12.0V, 1.0SA (1.2A max.)

Working range

12V ±10%

Sound

output

400mW max. (440

Hz)

Scan size Horizontal; 10% (lS% max.)

Speaker

Bem,

round dynamic type

Vertical; 10% (lS% max.)

(320)

Horizontal

Control knob Volume

lock-in range

±300

Hz

(±100Hz limit)

Brightness

Vertical

lock-in

raniJe

-12

Hz

(-6

Hz

limit)

Working

Audio

440

Hz

(OdB)

-10°C

to

SOOC

friquency

-lOdB

±4dB

at

100

Hz

temperature

characteristic

-12dB

±4dB

at

10kHz

.

Sound maxi-

400mW

at

440

Hz

mum

output

• Cassette tape recorder Section

System

PWM

recording

Biasing

DC

system

Power source

SV

±0.25V (rated)

Erasing

DC

system

Rated amperage

Wait; 2mA

Playback

1 m sec.

to

SOO/-l

sec. (standard)

Record;

70mA (TEAC test tape)

sensitivity

Playback; 7mA (TEAC test tape)

Input level

Below 0.4V

("l")

Semiconduc·

4 transistors

Over 2.0V ("H")

tors

1

IC

Input

Over

10kll

(record jack)

4 diodes

impedance

Applied tape

From C30

to

C120

Output

level

Below

O.4V

("l")

Over 2.0V

("H")

Tape speed

4.7S cm/sec. Working

-10°C

to

SOoC

Track

2-track monaural

type

temperature

Motor Electronic governor motor (12V)

Storage

-2SoC

to

70°C

temperature

NOTE

Specifications and appearance are subject

to

change

without

prior notice for improvement.

In

such

a case,

the

explanation here may be a little different from

the

product.

-2-

The machine comprises five main units, CPU board, display, cassette

tape

recorder,

keyboard,

and power supply

circuits. For a quick solution

to

most

operating difficulties, first

consult

the

chart

below

to

find which section

of

the

machine

is

subjected

to

the

trouble, and

do

the

checkings according

to

more

detailed instructions given

in

the succeeding pages.

Start

Switch

on

Yes

I

s

the

cassette

~ecorder

normal?

Yes

End

No

-3-

Check

for

the

power

supply

circuit.

Check for

the

CRT

display.

Check

for

the

cassette

recorder.

Check

for

the

keyboard.

Check

for

the

CPU

board.

CPU BOARD SECTION

The CPU

board

is

composed

of

the

following six blocks. When it

gets

in

trouble,

first

locate

which

block

is

concerned

with

the

trouble,

and

to

check

for its

corresponding

circuits;

the

wiring

diagrams

of

every block

will be

shown

separately.

CPU

in

trouble

Display block

No

Cassette recorder block

Keyboard

block

Audio block

Clock block

No

Gets

in

trouble

instantly

with

power

on.

No

Yes

•

Checking-methods

of

each

circuit

Check

for

video

RAM

circuit.

Check

for

IC50

(8255)

and

its

peripheral

parts.

Check

for

IC50

(8255)

and

its

peripheral

parts.

Check

for

IC47

(8253)

and

its

peripheral

parts.

Check

for

IC47

(8253)

and

its

peripheral

parts.

Memory

circuit,

Reset

circuit

and

its

peripheral

parts.

1.

By

touching

IC

insulating parts by fingers:

'.:

If

they seem

too

hot

by heat generation;

IQ.oi~"j:fefl~ctive'-IC

load

-4-

~r(~':'\

V

;~:~.'~,

'l.~/

/

• Display Block

DO

-

Bus driver

07

-

~

-'--

--

WR-

RD

CSD

~

/

AO

I

)

A9

Who

le reversal

1.

Sync. signal

is

not

produced.

2.

Video signal

is

not

produced.

3.

Irregular display characters

4.

The display

is

positionally

deviated.

5.

Position

is

correct

but

characters are abnormal.

Character

h

:>

Video

signal

generator

~

Shift

register

<~/:.

L

)

BLNK

).

Sync.

signal

-

I

Video

'\/'

RAM

L--

1"1

Display

~

Oscillator

V

controller

circuit

Address selector

~

C~D

T

Block

Diagram

of

Parts

around

Video

RAM

Vertical sync. signal: Check

for

pin @

of

IC20.

Horizontal

sync. signal: Check

for

pin00f

IC20.

Is

V·GATE

signal

for

pin @

of

IC2 high level? Yes; IC2 No;

IC50

Is

V-BLANK

signal present at pin ®

of

IC20? Yes; IC20 No;

IC2

Is

H-BLANK

signal present at pin

CD

of

IC20? Yes; IC20, IC31 No;

IC2

Does pin ®

of

IC8 develop video signal? Yes; IC8 No;

IC2, IC10, IC4

Check IC14,

1<;:20.

Check IC21, IC22, IC26, IC27, IC32,

IC33

Check IC15 and IC16.

-5-

•

Cassette

recorder/Keyboard Block

PC1

D7

-\

PC5 PC4

PC3

-I

LO

In

'"

~

DO

Q)

u

-

~

e

RD

c

WR

-

~

Q)

.r:

PA3

Q.

-

.;:

~

Q)

"-

Q)

:0

cs

co

PAO

E

-

E

~

Al

Cl

PB7

e

-

0-

)

-

AO

RESET

PBO

r

...h

r

J,

I

1

l

I I

t-'

1)

L

Motor controller

I"

I

Decoder

I

1,

I

~

I

I I

J,

L

-------,

WRITE

READ

SENSE

I

I I

I

Cassette

I

MOTOR

I

______

-.1

------1

9

~

o

I

Keyboard

H I

) i

A :

_______

J

Block

diagram

of

Parts

around

Cassette

recorder/Keyboard.

1.

"LOAD"

operation

is

impossible.

2.

"SAVE"

operation

is

impossible.

3.

Motor

doesn't rotate.

4.

Motor

doesn't stop.

5.

Key

input

is

ineffective.

Is

output

signal present at pin Q)

of

IC10? Yes; IC50 No;

IC10

Is

output

signal present at pin @

of

IC50?

Yes;

ICl

0

No;

IC50

Is

voltage at pin ®

of

IC39 at

"Iow"

level?

Yes;

IC4,

01

No;

IC39, IC5

Is

voltage at pin ®

of

IC39 at

"high"

level?

Yes;

IC4,

01

No;

IC39, IC5

Check

for

IC52 and IC50.

•

Audio/Clock

Block

RD

----;

WR---i

Programmable

counter

(8253)

"-

--------------

~-'"

------------

-------.--------~---

31.5KHz

")

_

~

Clock

function

INT

J

1/2

frequency

division

I-------C>

Audio

output

CS

----;

A1

------1

1-----<

2MHz

AO---L

____

~

WR----1

CS

------1

RD-----4

Latch

Oscillator circuit

for

Tempo

L--,-

_____

..4

DO

Block Diagram

of

Parts

around

Audio/Clock

Block

1.

Abnormal sound

output

2.

Clock

function

is

abn·ormal.

--r,.,..,,

__________

..

___

---------

Is

output

signal present

at

@

of

IC47? Yes; IC45, IC48 No;

1C47, IC51

Is

31.5KHz

signal

input

to

pin @

of

IC47?

Yes; 1C47 (8253) and surrounding are

faulty.

No; IC20 (Check

if

8MHz

signal

is

supplied

to

pin @

of

IC20)

-7-

~-~-~----~

~~--~---~---~

•

Memory

Circuit

Block

Data

selector

WR

RAM

block

07

DO

Memory

control

circuit

ROM

A15

\

A12

CPU

control

Bus

AO~All

DO~D7

Block

Diagram

of

Parts

around

Memory

Circuit

1.

Reproduced picture shows "panic".

2.

Error display

or

misoperation

is

caused

as

a result

of

program

execution.

3.

Returns

to

"MONITOR

SA-1510".

4. Error

is

caused

after

a long operation.

Check

for

the

following:

ROM, IC46, CG,

IC13

(CPU) and surrounding

circuit Address bus line Data bus line

Control

line

RAM

(by using

RAM

checker),

RAM

check

RAM

check

RAM

check

~8~

*

How

to

Use

RAM

Checker

Remove

monitor

ROM from

the

socket

("M-ROM"

marked

on

the

PWB)

and

insert

RAM

checker

into

the

socket

and

turn

on

the

power

switch (the

picture

gets

"panic"

for

about 1 second):

then

the

following

RAM

TEST-l

and

RAM TEST-2 will be

automatically

carried

out

from

the

address

$1000

to

the

maximum address

and

the

tested

results

wi

11

be displayed_

The following

is

an

example

of

the

testing

performed

with

the

standard

set

(with RAMs being all normal).

Note: RAM 32K

bytes

RAM

TEST-l

RAM

TEST-2

1) RAM

TEST-l

1000-0K 6000-0K 00

FF

2000-0K 700o-0K

00

FF

3000-0K

800o-0K

FO

OK

4000-0K

5000-0K

9000-ER-9000,00,7F

In

the

range from

the

address

$1000

to

the

maximum

address,

data

$00

and

$FF

are subjected

to

auto-

matic

write/read

test;

if

error

is

caused,

"ER"

mark

is

indicated in

the

unit

of

4K

bytes_

In

the

above table,

3000-0K:

this

means

write/read

operation

has been normal

from

the

address

$3000

to

$3F F F_

9000-ER-9000-00,7F:

this

means

there

exists

error

somewhere

from

the

address

$9000

to

$9FFF;

this

error

is

because

the

standard

set

is

provided

with

up

to

$8FFF

but

with

no

more address, so it

doesn't

show a malfunction

of

RAM

itself.

An

example

showing an

error

really caused:

200Q-E R-235B-00, 01

An

error

is

caused in

the

addresses

$2000s;

namely,

although

data

$00

has been

written

in

the

address

$235B,

its

read-out

data

is

$01.

2) RAM TEST-2 Write/read

test

is

carried

out

with

the

following

data.

(a) Write-in

data

$00

(from

the

address

$1000

to

the

maximum

address)

(b) Write-in

data

$F

F (from

the

address

$1000

to

the

maximum

address)

(c) Write-in

data

$00

(from

the

maximum

address

to

the

address

$1000)

(d) Write-in

data

$FF

(from

the

maximum

address

to

the

address

$1000)

(e) Write-in

data

$FO and

$OF

to

be

entered

alternately

(from

the

address

$1000

to

the

maximum

address

and

vice versa).

The above

table

(RAM TEST-2) shows

all

the

items (a)

thru

(e) are normal -

the

indications

"00",

"FF",

"00",

"FF"

and

"FO"

correspond

to

(a)

thru

(e) respectively.

An

example

showing an

error

really caused:

RAM

TEST-2

00

FF

00

ER-23FF-Ol

From

the

above, it can be seen

that

the

tests (a)

and

(b) are

both

normal

and

that

although

data

$00

in

the

test

(c) has been

written

in

the

address

$23F

F, its

read-out

data

is

$01,

which means

that

an

error

has been caused.

In

this way, which RAM

block

(I,

II

or

Ill)

has been

subjected

to

the

error

is

first

located,

and

then

so does

which RAM

component

having undergone

the

error,

by

the

respective

information

given by

the

RAM tester.

In

the

above example,

the

display

of

"$23FF"

means

RAM

(I)

block

is

in

trouble,

and

the

display

of

read-out

data

"$01"

(with respect

to

write-in

data

"$00")

shows RAM 1

of

the

block

(I)

is

defective.

-9-

Write-in

data

$00

Read-out

data

$01

f~AM

1II.

00 01 02

03

04

05

06

07

I I

I

17

I

18

I

19

I

20

I

21

I

22

I

23

I

24

I

07

06

0

RAM n '

RAM

I

9

I I

1

I

10

I

2

I

11

I

3

I

12

I

4

I

13

I

5

I

14

I

6

I

15

I

7

I

16

I

8

I)

I

I I I

I I

I

-~-----~"-.~

~

-----~-

~----------

-" -_._-----

05

04

0 0

03

02

01

0

RAM

(I)

$1000 ~ $4FFF

RAM

(Il)

$5000

~$8FFF

RAM

(Ill)

$9000 ~ $CFFF

00

IT]

Error

--

to

occur

• Wave

form

of

Each

of CPU

Board

-------

---------~~

------~----~------------.----------------.

At

11

of

le

20

(31.5

KHz)

At

Pin 4

of

le

3

At

Pin 8

of

le

11

(Horizontal

Blanking

Signal)

At

10

of

le

50

(Vertical

Blanking

Signal)

.~---~-----+----------------+---------------1

At

10

of

le

20

(Vertical

Sync.

Signal)

-

10-

At

Pin 4 of

le

3

Write-in

d3tJ

$00

Fiead-out

data

$01

DO

01

0:)

D3

04

0

,-

,)

D6

D7

"'\iv1

ill

I

1'1

I

IR

I

1 q

I

?ll

I

:'1

I

??

I

L)I

I

I',;

]

L--

I

07

o

f

-<

~'\

~\J'I

"

1 C

TI

I

11

I

1?

I

n_~

I

1

~

I

I'

I

L"

I

06

o

"t\;\

1

I

1

I

2

I

\

I

,I

I

s

I

tl

I I

j

I

I I

05

o o

04

o o

03

02

01

o o

RAM(l)

o

$1000 ~ $4FFF

RAM (Il)

$5000

~$8FFF

RAM

(Ill)

$9000 ~ $CFFF

DO

Error

--

to

occur

•

Wave

form

of

Each Pin

of

CPU Board

At

11

of

IC

21)

(31,5

KH,)

At

-4

of

IC 3

- T

!

At

Pin 8 of

IC

11

(Horizontal

Blanking

Signal)

AtPin

10

oflC20

(Vertical

Sync,

Signal)

---------

----,---

------

-

----------

-----------l

I

At

10

of

IC

50

(Vertical

Blanking

Signal)

At

Pin 4 of

le

3

_________

-1-

_______________

--'--

______________

----'

-10-

....

I

Audio

signal

Video

signal Contrast

Vertical

horizontal

sync. signal

+12V

Power

supply

Video

amp.

02001

02002

t

Beightoe"

Vert. sync.

signal

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

Sync. amp.

02003

To video amp.

To sync.

separator

To

vert.

circuit

To audio

circuit

Horiz. sync.

signal

To

horizontal

circuit

To

FBT

circuit

To CRT heater

Vert.osc.

amp'/output

amp. IC2001

ttt

V-HOLD

V-LlN

V-SIZE

AFC

H

Horiz.

02003,

osc.

02004

~

H-HOLO

Volume

Horiz.

drive

02005

Audio

signal

amp.

IC2002

Video signal

Horiz.

output

02006

Block Diagram

of

Display Section

)

I----~IIO

~~~

Speaker

Cl0M36P31

or

E2728B31

9"

'\'+-

HV

H~

'\

• • Middle voltage

FOCUS

F.B.T

c

-

(J)

-C

~

en

~

-I

-

o

z

• Trouble Shooting Chart

Problem 1: No picture appears.

[

No

picture

1

Nri

Check CPU board.

I

NOl Check

I

CPU board.

Only

H Check

Check

VR-2002

YChKk

Video

Check

02001.02002

and

r

raster

+12V

power

~

input

signal.

-

video

vide0-40V

power

supply.

appears.

Yes

circuit.

supply.

- -

Yes

Neither

(02009.

02010

L..>

raster

nor

02007)

picture

No

appears.

rl

Check

CRT

plug.

I

Chcek

middle!

Yes

high voltage

J

--.j

Defective CRT.

r

rectification

Check

Yes

(02006,02009

and

ri Defective

CRT.

FBT.)

L..."

CRT heater.

Yes

~-

Check high voltage at

K,

r---

Check

AFC,

~

G1,

G2

and

~.

Check

horizontal

G3

of

CRT.

No

FBT

circuit.

oscillator

and

No

drive

output

circuit.

Problem 2:

Sync

operation remains ineffective.

NH

Check CPU

I

Neither

Check sync.

board.

r-"

horizontal

nor

separation

(02001

vertical sync.

and

020031.

operation is

llsthere

r

ineffective.

sync.

Check integrating.

signal?

Only

vertical

Circuit

(R2030

to

R2023.

Yes

sync.

operation

and C2011

to

C2013).

is ineffective.

Only

horizontal

Check

AFT

circuit

--10

sync. operation

(Check

point

(j)

output

of

is

ineffective.

FBT.

R2030.

C2021.

R2033.

R2055

and

C2055)

Problem 3: Raster

is

too

narrow.

N~

Chcek

V-HOLD

VR,

I Check

C2010

and

R2014.

Is vertical asci I·

latior

waveform

f----

No

~

R2016

and I

normal (at

@)

C2007.

NrlDefective

IC2001.j

of

IC2001)?

Is

input

waveform

......

of

IC2001

(at

-

Yes

(7))

normal?

Is

output

Yes

...........

waveform

of

IC2001 normal?

r--Y'Check

deflection

coil

(C20161.

Yes

I

Problem 4: No sound comes

out.

Again set correct

program.

Is

there

audio

signal?

.-----.ot

Check CPU board.

Yes

Is

input

signal

of

IC2002

(at pin@) normal?

-12

-

No

Yes

Chceck

VR.

R2050and

C2043

Is

output

si{Jlal

~~C2002

1---1

(at

pinl,J,)

normal?

Defective IC2002.

Check

C2053

and

speaker.

Sharp MZ-80A Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual