Morrow Micro Decision MD-1, Micro Decision MD-2, Micro Decision MD-3 Service Manual

MICRO

DECISION

MODELS

MD-l

I MD-2 I MD-3

SERVICE

GUIDE

Copyright

1983

by

Morrow

Designs,

Incorporated

600

McCormick

Street

San

Leandro,

California

94577

All

rights

reserved.

THE

SERVICE PROCEDURES DESCRIBED

IN

THIS

DOCUMENT

ARE

TO

BE

PERFORMED

ONLY

BY

AUTHOR-

IZED

MORROW

DESIGNS DEALERSHIPS.

ONLY

QUALI-

FIED

SERVICE PERSONNEL SHALL PERFORM

THE

REPAIRS~·······_--UU.AJ:,TFTC.ATTON··M.AY·····

··BE·····OBTAINED·········BY

SATISFACTORY

COMPLETION

OF

A

MORROW

DESIGNS

SERVICE SEMINAR.

No

part

of

this

publication

may

be

reproduced,

transmitted,

stored

in

a

retrieval

system

or

translated

into

any

language

or

computer

language,

in

any

form

or

by

any

means,

eletronic,

mechanical,

magnetic,

optical,

chemical,

manual,

or

otherwise,

without

the

prior

written

permission

of

Morrow

Designs,

Inc.

No

representations

or

warranties,

express

or

implied,

are

made

with

respect

to

the

contents

hereof,

including,

but

not

limited

to,

the

implied

warranty

of

merchantability

or

fitness

for

a

particular

purpose.

Further,

Morrow

Designs

reserves

the

right

to

revise

this

publication

and

to

make

changes

from

time

to

time

in

the

contents

hereof

without

obligation

to

notify

any

person

of

such

revision.

Diagnostics

II

is

a

product

of

SuperSoft,

Incorporated.

The

documentation

contained

herein

for

this

product

is

reproduced

with

the

permission

of

SuperSoft.

PART

I - TECHNICIAN'S REFERENCE:

COMPONENT

ID

AND

DISASSEMBLY

PREFACE

The

Micro

Decision

Service

Guide

is

organized

in

two

distinct

parts.

Part

I

serves

as

a

technician's

reference

guide;

the

modular

assembly

of

the

Micro

Decision

is

discussed

in

detail,

and

the

disassembly

procedures

for

each

module

is

provided.

Troubleshooting

and

parts

replacement

is

also

covered

in

Part

I.

Part

II,

Diagnostics

II

User's

Manual,

follows

the

Customer

Service

Bulletin

Index.

This

part

of

the

Micro

Decision

Service

Guide

details

the

testing

of

each

major

Micro

Decision

component.

The

Morrow

Designs

Micro

Decision

computer

system

is

designed

for

serviceability.

A

reduced

part

count

and

modular

assembly

approach

contribute

to

reliability

and

ease

of

service.

The

Central

Processing

Unit,

memory

circuits,

communications

port

and

all

support

electronics

reside

on

a

single

printed

circuit

board

("motherboard").

One

power

supply

assembly

provides

all

DC

operating

voltages

to

the

motherboard

and

the

internal

disk

drives.

The

motherboard,

power

supply,

and

disk

drives

are

typically

replaced

as

complete

units.

Thus

repairs

can

usually

be

performed

with

a

minimum

of

troubleshooting

for

you

and

downtime

for

the

owner.

No

special

tools

are

required,

beyond

normal

hand

tools.

A

digital

voltmeter

is

needed

for

power

supply

troubleshooting

and

cable

continuity

tests.

User-selectable

options

are

limited

to

baud

rates,

hardware/software

printer

handshaking,

and

terminal/modem

selection

for

the

RS-232

connectors.

These

are

described

in

the

Micro

Decision

User's

Guide.

Refer

to

the

User's

Guide

for

an

introduction

to

the

system

and

operating

instructions.

The

intent

of

this

manual

is

to

guide

you

through

module

replacements.

To

this

end,

disassembly

procedures,

troubleshooting

flowcharts,

and

SuperSoft's

Diagnostics

II

documentation

are

included.

If

you

attempt

to

perform

repairs

at

a

component

level,

you

do

so

at

your

own

risk

and

with

the

knowledge

that

doing

so

voids

any

remaining

factory

warranty

on

the

unit.

TAB

L E o F

CON

TEN

T S

1.

TOOLS REQUIRED FOR DISASSEMBLy

•••••••••••••••••••••••••••

1-1

CO~R

~O"AL

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

2.

2.1.

2.2.

Revision

A

Chassis

••••••••••

Revision

Band

C

Chassis

••••••••••

2-1

2-2

2-4

3.

DISK

3.1.

3.2.

3.3.

3.4.

DRIVE CONFIGURATION

AND

REMO"AL

•••••

MDIand

MD

II

-

Revision

A

Chassis.

MD

III

-

Revision

A

Chassis

••••••••••••••••

MDIand

MD

III

-

Revision

Band

C

Chassis

••

MD

II

Revision

Band

C

Chassis

•••••••••••

3-1
3-1
3-2
3-2

3-4

4.

POWER

SUPPLY

REMO"AL

•••••••••••••••••••••••••••••

4.1.

Revision

A

Chassis........

•

••••

4.2.

Revision

Band

C

Chassis..

•

••••

4-1
4-1
4-1

MOTHERBOARD

RE"ISIONS

•••••

5.

5.1.

5.2.

5.3.

Revision

1.1

Details.

Motherboard

Removal

•.

Revision

2.0

Features

•.

5.3.1.

Parallel

Port

••.

5.3.2.

Serial

Ports

••••••••••

5.3.3.

40

Pin

I/O

Connector

••

5.3.4.

ROM

Diagnostics

•••••••

5.3.5.

Drive

Expansion

•••••••

5.3.6.

Disk

Drive

Connector

••

5-1
5-1

5-3

5-3

5-7

5-8
.5-16
.5-17
.5-18

.5-19

6-1

6-1

6-1

6-5

6-5

Tools

Required

••••••••••••••••••

Troubleshooting

Flowchart

••••••••••••••••••••••

Measuring

Power

Supply

Voltages

••••••••••••••••

Tips

on

Troubleshooting

Power

Supply

Problems

••••

TROUBLESHOOTING PROCEDURES

••••••••••

6.1.

6.2.

6.3.

6.4.

6.

7.

REPLACEMENT PARTS

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

7-1

8.

CUSTOMER

SERVICE BULLETIN INDEX

••••••••••

8-1

LIS

T o F

FIG

U

RES

2-1:
2-2:

2-3:

2-4:
2-5:

2-6:

2-7:

3-1:
3-2A:
3-2B:
3-3:

3-4A:

3-4B:

3-4C:
4-1:

Revision

A

Chassis

•••••••••••••••••••••••••••••••••••••

Revision

B

Chassis

•••.•••••••••••••••••••••••••••••••••

Revision

C

Chassis

•••••••••••••••••••••••••••••••••••••

Cover

Removal

-

Revision

A

Chassis

•••••••••••••••••••••

Location

of

Screws

-

Revision

A

Chassis

••••••••••••••••

Location

of

Screws

-

Revision

B

Chassis

••••••••••••••••

Location

of

Screws

-

Revision

C

Chassis

••••••••••••••••

MD

I/MD

II

Drive

Removal

-

Revision

A

Chassis

••••••••••

MD

I/MD

III

Drive

Removal

-

Revision

Band

C

Chassis

•••

MD

I/MD

III

Drive

Removal

-

Revision

Band

C

Chassis

•••

Separating

MD

III

Drives

-

Revision

Band

C

Chassis

••.•

MD

11-

Revision

Band

C

Chassis

-

Drive

Removal

••••••••

MD

11-

Revision

Band

C

Chassis

-

Drive

Removal

••••••••

MD

11-

Revision

Band

C

Chassis

-

Drive

Removal

••••••.•

Power

Supply

Removal

•.•••.•••••••.••••..•••••••••••••••

2-1
2-1
2-2

2-3
2-3

2-4
2-5

3-2
3-3
3-3

3-4

3-5

3-5
3-6

4-2

5-1:

5-2:

5-3:

5-4:
5-5:
5-6:

5-7:

5-8:
5-9:

5-10:
5-11:

Micro

Decision

Rev

1.1

Motherboard

•••••••••••••••••••••

5-1

Rev

2.0

Motherboard

-

Kohjinsha

••••••••••••••••••••••••

5-5

Rev

2.0

Motherboard

-

Korean

Assembled

•••••••••••••••••

5-6

Serial

Port

Pin

Arrangement

-

Rear

View

••••••••••••••••

5-8

Factory

Jumper

Settings

for

JPA

••••••••••••••••••••••••

5-10

JPA

Settings

for

Modems

••••••••••••••••••••••••••••••••

5-11

Jumper

Settings

(Pin

2

to

Pin

2,

Pin

3

to

Pin

3)

•••••••

5-11

Factory

Jumper

Settings

for

JPB

••••••••••••••••••••••••

5-13

JPB

Jumper

Settings

(Crisscross

Modem

Cable)

•••••••••••

5-14

Alternate

JPB

Jumper

Settings

•••.••••••••••••••••••••••

5-14

Drive

Expansion

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

5-19

LIS

T o F

TAB

L E S

5-1:
5-2:
5-3:
5-4:

5-5:
5-6:
5-7:
5-8:
5-9:
5-10:

5-11:
5-12:
5-13:
5-14:

Micro

Decision

Rev

1.1

Port

Addresses

••••••••••••••••••

5-2

Rev

1.1

Bit

Map

(RAM

Location)

•••••••••••••••••••••••••

5-2

Micro

Decision

Revision

2.0

Port

Addresses

•••••••••••••

5-4

Rev

2.0/Kohjinsha

Bit

Map (RAM

Location)

•••••••••••••••

5-5

Rev

2.0/Korean

Assembled

Bit

Map

(RAM

Location)

••••••••

5-6

Parallel

Port

Addresses

••••••••••••••••••••••••••••••

5-7

Parallel

Port

Signals

{Kohjinsha

Rev

2.0

Board)

••••••••

5-7

Parallel

Port

Signals

(Korean

Assembled

Rev

2.0

Board).

5-8

RS-232

Signal

Descriptions

•••••••••••••••••••••••••••••

5-9

JPA

Pinouts

{Terminal

Setup)

••••••••••••••••••••••••••

5-10

JPB

Pinouts

(Terminal

Setup)

•••••.••••••••••••••••••••

5-12

Sample

RS-232

Cable

Configurations

••••••••••••••••••••

5-15

40

Pin

I/O

Connector

-

Pin

Connections

••••••••••••••••

5-16

Disk

Drive

Connectors

-

Pin

Connections

•••••••••••••••

5-20

6-1:

Troubleshooting

Flowchart

••••••••••••••••••••••••••••••

6-2

7-1:

Replacement

Parts

List

•••••••••••••••••••••••••••••••••

7-1

7-2:

Dealer

Service

Kit

••••.••.••..••.••••.••.••.••••••••••.

7-2

Part

I-Section

1:

Tools

Required

for

Disassembly

1.

TOOLS

REQUIRED

FOR

DISASSEMBLY

(09/23/83)

You

will

need

a

Phillips

screwdriver,

preferably

size

12

and

magnetic..

Keep

any

magnetized

tools

away

from

diskettes

that

contain

valuable

files.

To

help

insure

against

callbacks,

you

should

wear

a

grounding

wriststrap

that

is

connected

to

the

Micro

Decision

chassis

whenever

you

handle

the

mother

board.

1-1

Part

I-Section

2:

Cover

Removal

(09/23/83)

2 • COVER REMOVAL

Before

removing

the

cover,

turn

off

the

Micro

Decision

and

unplug

the

equipment

from

the

ac

power

source.

Failure

to

do

so

pre-

sents

a

serious

hazard

to

the

equipment

and

to

service

personnel.

Next,

disconnect

all

cables

from

the

rear

of

the

unit.

At

this

printing,

Morrow

has

installed

three

versions

of

Micro

Decision

chassis.

For

clarification,

we

refer

to

them

as

Revi-

sion

A

(original

model),

Revision

B,

and

Revision

C

(newest

chassis

style).

The

simplest

way

to

distinguish

the

three

chassis

reVlSlons

is

to

view

the

unit

from

the

rear.

Revision

A

has

a

cord

pan

installed,

and

the

AC

power

cord

is

hardwired

(see

Figure

2-1).

@

c::==:=J

c==J

Figure

2-1:

Revision

A

Chassis

The

Revision

B

chassis

does

not

have

a

cord

pan,

and

the

power

cord

plugs

into

the

back

of

the

unit.

Figure

2-2:

Revision

B

Chassis

2

.,~

'1

Part

I-Section

2:

Cover

Removal

(09/23/83)

The

third

chassis

style

(Revision

C)

is

similar

to

the

Revision

B

chassis,

but

can

be

identified

by

the

knockout

provided

on

the

rear

panel

for

a

fan.

The

fan

is

installed

in

MD

XI

units

only.

Another

distinguishing

characteristic

is

the

location

of

the

drive

expansion

knockout.

It

is

located

in

the

upper

right

portion

of

the

Revision

C

rear

panel,

rather

than

at

the

base.

The

Revision

C

chassis

also

has

two

screws

provided

for

removal

of

the

Micro

Decision

motherboard.

FAN KNOCKOUT

MOTHERBOARD

REMOVAL

Figure

2-3:

Revision

C

Chassis

2.1.

Revision

A

Chassis

1.

Remove

the

four

screws

on

the

bottom

that

hold

the

cover

to

the

chassis

(see

Figure

2-4).

2.

Now

remove

the

two

screws

at

the

upper

corners

of

the

unit's

back

that

hold

the

cover

to

the

back

panel.

3.

Carefully

remove

the

cover

by

sliding

it

off

towards

the

front.

2-2

Part

I-Section

2:

Cover

Removal

(09/23/83)

00

o

o

o

o 0

o

o

o

o

o

o 0

Figure

2-4:

Cover Removal -

Revision

A

Chassis

(

''''~

,)

()

o

!

MOTHERBOARD

SCREW LOCATIONS

()

o

,,)

/

()

."

..

""""

•.

",~-'""~,

..

"

...

"

...

,~

..

"

..

"",,

....

,"".

"-----."-,,.,,---,,,,--,,------

1111111

1111

III

!III"""

o

'.J

--~

Figure

2

5:

Location

of

Screws

-

Revision

A

Chassis

Part

I-Section

2:

Cover

Removal

2.2.

Revision

Band

C

Chassis

(09/23/83)

1.

Remove

the

four

screws

closest

to

the

edge

(two

on

either

side).

NOTE: A

magnetized

screwdriver

is

not

required

when

working

on

Revision

Band

C

chassis.

2.

Tip

the

unit

and

rest

it

on

the

rear

panel.

3.

Slide

the

cover

up

and

off.

r---,

®

~

e",

/e

~

MOTHERBOARD

SCREW LOCATIONS

@

I

\

E!)

'----

E9

~

@

Figure

2-6:

Location

of

Screws

-

Revision

B

Chassis

2·-4

Part

I-Section

2:

Cover

Removal

(09/23/83)

r---,

ffi

~

'"

/(9

~

MOTHERBOARD

SCREW LOCATIONS

EB

~

L.--

@@

Figure

2-7:

Location

of

Screws

-

Revision

C

Chassis

Part

I-Section

3:

Disk

Drive

Configuration

and

Removal

(09/23/83)

3.

DISK

DRIVE CONFIGURATION

AND

REMOVAL

There

are

three

drive

configurations

for

the

Micro

Decision:

MD

I -

One

3/4

high,

single

sided,

5

1/4

inch

floppy

drive,

mounted

at

the

left

(as

you

face

the

unit)

MD

II

- Two

3/4

high,

single

sided,

5

1/4

inch

floppy

drives,

mounted

side

by

side

MD

III

- Two

1/2

high,

double

sided

floppy

drives,

stacked

(drive

B

mounted

above

drive

A)

in

the

left

half

of

the

unit

(as

you

face

the

front)

Drive

removal

depends

on

the

configuration

of

the

drives

and

the

type

of

chassis

in

which

these

drives

are

installed.

NOTE:

When

removing

MD

II

or

MD-

III

drives

from

a

Revision

1.1

motherboard,

it

is

very

important

that

you

mark

disk

drives

as

A

or

B,

since

they

must

go

back

in

the

same

positions

from

which

they

came.

The

best

method

is

to

place

a

piece

of

masking

tape

on

the

B

drive

with

a

note

"next

to

power

supply".

3.1.

MDIand

MD

II

-

Revision

A

Chassis

1.

Turn

the

unit

upside

down

and

remove

the

three

screws

that

anchor

the

drive

you

wish

to

remove.

Figure

3-1

points

out

the

positions

of

the

screws

for

both

drives.

2.

While

holding

the

loosened

drive

in

place,

turn

the

unit

right

side

up.

Disconnect

the

drive

cable

and

carefully

pull

it

backwards

out

of

the

chassis.

3-1

Part

I-Section

3:

Disk

Drive

Configuration

and

Removal

(09/23/83)

o

0'--

00

II

~o

o 0

--

....

0

o 0

o

o

o 0

Figure

3-1:

MD

I/MD

II

Drive

Removal

-

Revision

A

Chassis

3.2.

MD

III

-

Revision

A

Chassis

1.

Follow

the

instructions

provided

for

MD

I

and

MD

II

drive

removal

(Section

3.1).

2.

Remove

the

strap

which

holds

the

two

drives

together.

Remember

to

mark

one

or

both

of

the

drives:

drive

B

must

be

reinstalled

on

top

of

drive

A.

3.3.

MDIand

MD

III

-

Revision

Band

C

Chassis

1.

Disconnect

the

flat

ribbon

cable(s)

from

the

connector(s)

on

the

drive(s).

Then

disconnect

the

cable(s)

to

the

motherboard.

For

MD

III

configurations,

we

recommend

that

you

mark

the

cables

for

drive

B

to

identify

them

when

reinstalling

the

drive.

2.

Remove

the

two

bottom

screws

from

the

brackets

on

the

left

(see

Figure

3-2A).

3-2

Part

I-Section

3:

Disk

Drive

Configuration

and

Removal

(09/23/83)

Figure

3-2A:

MD

I/MO

III

Drive

Removal

-

Revision

Band

C

Chassis

3 •

Remove

the

screw

at

the

base

of

the

ilL"

bracket

on

right

side

as

viewed

from

the

front

of

the

unit

Figure

3-2B).

the

(see

Figure

3-2B:

MD

I/MD

III

Drive

R,emc)val

,-

I~evisi.on

Band

C

Chassis

4 •

~.:;,

1 i d

f'

t"

II(' d r

i,

v(' (:;) t

()w

tt

r

cl

til

p r

par

';:1

nd()u t .

Part

I-Section

3:

Disk

Drive

Configuration

and

Removal

(09/23/83)

5.

To

separate

and

remove

individual

drives

(MD

III),

remove

the

two

bottom

screws

from

the

straps

on

the

right

side

of

the

drives.

Figure

3-3:

Separating

MD

III

Drives

-

Revision

Band

C

Chassis

3.4.

MD

II

-

Revision

Band

C

Chassis

1.

Remove

the

cable

connectors

from

the

drive

you

wish

to

remove.

2.

Remove

the

screw

at

the

base

of

the

bracket

holding

the

two

drives

(see

Figure

3-4A).

3-4