Sams 26-3134, 26-3136, COLOR COMPUTER 2 Technical Service Data

CC15

08970

COMPUTER:

RADIO

SHACK

TRS-80

COLOR

COMPUTER 2

MODELS

26-3134,

26-3136-

TECHNICAL

SERVICE DATA

FOR

YOUR

COMPUTER

SAM

S

COMPUTERFACTS'

RADIO

SHACK

COLOR

MODELS 26-3134, 26-3136

COMPUTER

2

CM
cc

HI

H
3

0.

2

O
o

CC

O

=!

R<o

O CM

* (A

o

<

o

Q
<

CC

IO
T"

o
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PRELIMINARY

This

data provides the user with

which is designed

puter malfunctions.

£

m

n

<6

<*
<*

n
«

H

£

s

Check ail interconnecting

correct

hookup before making

Disconnect all peripherals

Computer to eliminate possible external

TEST

TEST

Digital

Logic Probe

Frequency

TV

EQUIPMENT

EQUIPMENT

Volt/Ohm

Counter

Monitor

SERVICE CHECKS

for quick isolation and repair

Meter

a time-saving service tool

cables for good connection

service checks.

except the Monitor

malfunctions.

AND

TOOLS

of Com-

and

from the

TOOLS

Low Wattage

Desoldering

Contact

Phillips

Flat

Blade

IC Insertion and

Alignment

Soldering

Equipment

Cleaner

Screwdriver

(non

Screwdriver

Removal

Tools

GC

Iron

spray

type)

Tools

Electronics

14,

9440

16, 24

and

40 pin

SAMS

The

listing of any available

constitute in any

Howard W.

replacement

from

information

manufacturers

case

Sams

& Co.,

part. The

furnished to Howard

of the particular type

REPLACEMENT

IDENT

D3
D4

IC1

IC2
IC3
IC5
IC7
IC8
IC9

IC11

IC13
IC14

thru

IC21

IC22 MX6198

Q1

R2

RY1

SW1

T1 ATA

recommendation,

a

Inc..

numbers of these

PART NO.

DX2321
DX2321

MX6201

AMX4578

MX6202

AMX4227

MX6211

AMX4575

MX5560

AMX4583

MX6200

MX6199

2SD526

N0001EGE

AR8166

AS2900

1056 Transformer,

Howard

4300 West

replacement part

a5

warranty or guaranty

to the

quality

parts have been compiled

W. Sams

of replacement pari listed.

W.

62nd Street,

herein does not

and suitability of such

& Co.,

PARTS

DESCRIPTION

Diode,

30D1

Diode, 30D1

IC,

SC77527P

IC,

MC6821P

IC,

SC77526P

IC,

SN74LS273P

IC,

SC67331P

IC, MC6847P
IC,

MC6809EP

IC, SN74LS138N
IC,

804236

IC,

RAM

MB8118-12P

IC,

74LS783

Transistor

Resistor,

Relay

Switch,

Sams

Inc.,

Power

& Co.

P.O. Box

by

the

by

.1

ohm, 1W

Reproduction

content,

respect to the

%

4300

Printed

AND

Power

1986

DESCRIPTION

7092, Indianapolis,

or

use,

in any manner,

use of the information contained herein.

Howard W. Sams

West

Street,

62nd

in U.S. of America.

Indiana 46206

without express

is prohibited. No patent liability

P.O. Box 7092. Indianapolis,

Co.

&

permission, of editorial

86CC14969

U.S.A.

is assumed with

Indiana

46206 U.S.A.

DATE

or pictorial

4-86

PRELIMINARY

SERVICE CHECKS

(Continued)

CASSETTE

POWER

RESET

(SA)e

SOUND

RF

MODULATOR

(3A)(4B)

CHANNEL 4

<S>

CHANNEL 3

120MC

R2

OB)

s.ov

source

/

IC1

(IS)

©

6a)

SALT

o

PULSES

IC7

PI

A

C6A (6D

@

©

PULSES

@©@

(g)

4

7

8

^9

IC2

P1A

KEYBOARD

3

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33

INTERCONNECTING

DIAGRAM

II

INTERCONNECTING

DIAGRAM

VIS

PRELIMINARY

SERVICE

CHECKS

(Continued)

©

©

MATCH

THE

COMPUTER

(A) Check

THE

NUMBERS

DEAD

for

A2. If the

and

A2, check

17.5VAC

voltage

open winding.

tween

the

power cord.

voltage

5.0V

check

of Transistor

at the

emitter

voltage is

Transistor

of the

center

winding and

Resistor

Check

secondary

an

open

(B) If the

check for

ing,

emitter

ent

(C) If the

check

D3 and D4.

If all

"Microprocessor

MICROPROCESSOR

(A) Computer

and

check

of the CPU

35

the

is

SAM IC (IC22)

NUMBERS

ON THE

between

is missing

Power

Transformer

Also

check for

tap of the

Connector

is correct

at the

voltages

dead. Check

at

5.0V source.

R2, check

Q1. If

of

Q1,

missing

Q1 and

Power

are

Operation"

OPERATION

IC (IC9).

SERVICE

ON THE

SERVICE

Connectors

at Connectors

(T1) for an

continuity

Power

Transformer

A3. Check

Connectors

the voltage

check

at the

IC1 . Also

Switch

correct,

section.

for

If

pulses are

by substitution.

A1 and

If

5.0V is miss-

for

5.2V at

Resistor R2.

emitter

check

(SW1).

refer

pulses

CHECKS

INTERCONNECTING

CHECKS

A1

is

pres-

of

Diodes

to the

at pins

missing,

and

A1

be-

for

A2,

the

Q1,

34

TO

BE PERFORMED.

(C)

SOUND

©

(A) No

(B) If

(C) If the pulses

KEYBOARD

(A) Keyboard

DIAGRAM

Colors

are not

3.579MHz

quency is not

Clock

Trimer

ments".

sound.

gram:

10 SOUND

Check for

pulses are present,

Sound Coil,

pulses are not

pulses

present,

check

PIA IC

tor

(CN2) for

correct. Check

at pin

correct,

TC1,

Also check

Type in and

200,200: GOTO 10

pulses

see "Miscellaneous

at pins

present

3

check

IC3

are missing

(IC2) by substitution.

is

dead. Check the

good

AND PHOTOS

7 of SAM IC

see "Miscellaneous

IC22

at pin

check

thru

8 of IC3. If the

by substitution.

connections.

for

(IC22).

check

the

by substitution.

run the

1 of DAC IC (IC3).

the

adjustment of the|

Adjustments"

at pin 1 of

pins

at

3

keyboard

WITH

a frequency

If the fre-

adjustment

Adjust-

following pro-

If the!

IC3, check

thru

pulses

8 of IC3,

Connec-

fori

are|

of

of

(B) If

check for

when

data pulses

(C) If data

and

thru IC21),

(IC13)

©

VIDEO

(A) No video.

(IC8)

(B) Dots are

Check (IC8)

Wrong

(C)

Latch IC

COLOR

©

(A) No color. Check for

(IC22).

1C22 by

If

(B)

the 3.579MHz signal is present

check the

pulses are

the

then

and the

present

data

Computer

present,

pulses

suddenly

ROM

by

substitution.

Check the

RF

missing

by substitution.

characters appear on the screen. Check

(IC5) and IC8

the

If

3.579MHz signal is missing, check

substitution.

at pins

pulses on

is turned

check

appear on

stop, check

IC(IC12)and

Video

Modulator

from

alphanumeric

by

3.579MHz at

and

34

pins

24 thru

On. If

IC9

pins

there

by

substitution.

24 thru

RAM

Expansion

Display

substitution.

Generator

by substitution.

pin

7 of SAM IC

pin

at

RF Modulator by substitution.

35 of IC9,

31

of IC9

are no

31 of

IC9

ICs (IC14

RAM IC

characters.

7 of IC22,

(B) If the keyboard

for

pulses at pin

pulses are

(C) If

pulses are

IC (IC7)

(D) A group

keyboard

tions.

CASSETTE

©

IC

(A)

Cassette

Check

of

run,

while saving

by substitution.

Also

Relay

Connector

check for

gram from

the time,

(B) If

Relay RY1

substitution.

(C)

Programs

and

DAC IC

(D) Programs

IC2 and

SALT IC

connector checks

11

missing, check

present

of keys

Connector

check

motor will not

of Decoder

at pin 11 of IC11,

do not

(CN2) for

IC7

by substitution.

run or

RY1 contacts

JK4. If the

continuity

a

program on

tape. If the cassette

check

for

checks

cannot

(IC3)

cannot

(IC1)

cassette

a short (relay

good, check

be saved

by substitution.

be

loaded from

by substitution.

IC11

by substitution.

work.

runs

between

between

tape or

motor

contacts

on tape,

good,

check

IC (IC11).

check

PIAJ

Check the

good connec-

all the time.

pins

and

1

motor

will not

pins

1 and

loading

PIA

tape.

runs

stuck).

IC (IC2)

Check

Check

a pro-

all of

IC2

If

3

3

by

III

PRELIMINARY

SERVICE

CHECKS

(Continued)

@@@(7D)

CLOCK

(4C)

TC1

^-^

PINS

34

AMD 35

PULSES

!C3

PSMS 24

THRU 31

PULSES

PULSES

1

PIN

11

ICT1

PIN

7

)(2A)

579MHz

lp\

C22

J

(4A)

2A)

33

>
g

s

o

O

OT

Q

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^

r

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O

to

t;

K>

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9

O

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*>

33

W

O

a>

o

w

S

w

"2

_l

m

3D

IV

PRELIMINARY

SERVICE

CHECKS

(Continued)

@@@(7D)

CLOCK

(4C)

TC1

^-^

PINS

34

AMD 35

PULSES

!C3

PSMS 24

THRU 31

PULSES

PULSES

1

PIN

11

ICT1

PIN

7

)(2A)

579MHz

lp\

C22

J

(4A)

2A)

33

>
g

s

o

O

OT

Q

I

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^

r

1

O

to

t;

K>

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9

O

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*>

33

W

O

a>

o

w

S

w

"2

_l

m

3D

IV

JOYSTICKS

(?)

(A) Joystick does

(B)

PRELIMINARY

not work,

following program:
10 FORX

20 Y

30 NEXT X: GOTO

=

=

JQYSTK(X)

0TO3

10

While the program is

pins

and

19

ing, check IC7 by substitution.

if

pulses

of PIA IC

39

are present at pins 19 and

check for pulses at

the pulses are missing at

IC11 by

substitution.

Type

running check

(IC7).

pin

11 of

pin

SERVICE CHECKS

SERVICE

in

and run the

for pulses at

If pulses are miss-

of IC7,

Decoder

39

IC <IC1

11 of IC11,

1).

check

If

(9_)

(Continued)

CHECKS

If pulses are present at

(C)

pulses

pulses

(D) If pulses are

check

Joystick buttons

(E)

joystick
joystick Connectors JK1 and JK2 for good con-

nections.

(F) If the joystick buttons and connectors are good,

check PIA

__

pins

at

are

4

missing,

present

DAC IC (IC3) by

buttons for

IC (IC7) by

SERIAL I/O PORT

Serial port

(A)

SALT IC (IC1)

not work. Check PIA IC (IC2) and

does

by

pin

thru

do

substitution.

11 of IC11, check for

of

9

PIA IC (IC2).

check

IC2 by

at pins 4 thru 9 of IC2,

substitution.

not work. Check the

continuity.

substitution.

substitution.

If the

Also check

POWER

The

with no

Computer

UP

Computer will come up

cartridge

come

will

RESET

The Computer

located on

(SW2)

PROGRAMS

BASIC

Basic

A

RUN

ing

stopped

be

CABINET

Remove sfx

Computer

MAIN BOARD

will be

program in the

and then pressing

pressing the

by

REMOVAL

Phillips screws

right side

REMOVAL

in the slot.

running the

up

Reset

right rear of

Computer

and remove

up

GENERAL

in Basic

If

cartridge

a

pressing

by

cabinet.

RAM

ENTER key.

the

BREAK key

from

OPERATING

mode when

program

can

or the

turned On

installed, the

is

in the cartridge.

the Reset

started by

be

program can

The

Reset button.

DISASSEMBLY

cabinet bottom.

cover.

button

typ-

Turn

INSTRUCTIONS

CASSETTE

Connect

the Computer using the cable furnished with the Computer.

Plug the black plug on the cable into the Earphone

large

into

To

load

mode with the

CLOAD and

pear

the program.

ter

F

after the

save

To

Record mode.

The

gram has

OPERATION

cassette recorder

a

gray plug into the Auxiliary jack and the small gray plug

the Remote On/Off

program from

a

volume turned about half

then

press the Return key. The letter

on the Monitor screen while the Computer searches for

the

will

When

appear on the screen and the word

program has been loaded.

a program to cassette, put the Recorder in the

Type CSAVE and

word

will appear on the Monitor screen after

OK

been saved and the Recorder will shut Off.

to the Cassette Socket

on the Recorder.

jack

cassette, put

Computer

the Recorder in Play

finds the

then

press the Return key.

(JK4)

jack,

way up.

program, the let-

OK

Type

will ap-

S

will appear

the pro-

on

the

INSTRUCTIONS

board. Remove six

cabinet

of Main board

tom

board.

POWER

and

base

TRANSFORMER REMOVAL

Phillips screws

remove board.

removing 17 clips that attach it to

by

holding Main

Remove shield from bot-

board

to

the

Carefully

remove

disconnect

Keyboard.

keyboard

Unplug

cable from

Power

Transformer

MISCELLANEOUS

CLOCK

Connect

(IC22).

3.579545MHz.

RF

Connect

VI

ADJUST

input

the

the

Adjust

MODULATOR

Computer

of

a

Clock

to a

frequency

counter to

Trimmer (TC1)

Monitor.

TV

for

Set

Main board

from Main

pin

of SAM

7

frequency

a

and

the TV

and

the

Unplug Power

Phillips screws

Transformer

holding

ADJUSTMENTS

Channel Select

the following program:

IC

of

10 SOUND

Adjust the Channel 4 Coil for best

just the sound coil for best sound

the TV

and the

Adjust the Channel 3 Trimmer

Switch

200,200:

Channel

from Main board. Remove two

Power Transformer to cabinet base.

to Channel 4. Type in and run

(SW3)

GOTO10

Select

t

picture and sound.

with minimum noise. Set

Switch SW3 to

for best picture and sound.

Channel

Ad-

3.

PRELIMINARY

SERVICE CHECKS

(Continued)

CASSETTE

POWER

RESET

(SA)e

SOUND

RF

MODULATOR

(3A)(4B)

CHANNEL 4

<S>

CHANNEL 3

120MC

R2

OB)

s.ov

source

/

IC1

(IS)

©

6a)

SALT

o

PULSES

IC7

PI

A

C6A (6D

@

©

PULSES

@©@

(g)

4

7

8

^9

IC2

P1A

KEYBOARD

3

>

g

2

o

w

r-

o

05 7!

M

O

9

O

55

^

w

O

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K)

O

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H
m

33

INTERCONNECTING

DIAGRAM

II

INTERCONNECTING

DIAGRAM

VIS

PRELIMINARY

ENVIRONMENT

SERVICE CHECKS

PREVENTATIVE

(Continued)

MAINTENANCE

Computers perform

dust and smoke particles.

as much

around the

Monitor, Printer, or

as

Computer.

best in

commercial

Do

other

ELECTRICAL POWER

Variations in

an AC receptacle

devices.

may

be

the line

that

A power-surge

needed

cure

to

voltage can

is

KEYBOARD

Liquids spilled into

Computer

power

disassemble the

water and

cleaner

DISK

Clean the

let it

and

DRIVES

read/write

Use only an

Handle

carefully

Drives

can knock the disk head

an old disk

in slot and

the

plug from AC

Keyboard

dry.

Use a

lint-free

wipers on accessible

heads of the Disk

approved head cleaning

preserve

to

close door during

clean,

a

cool

Even though

Computers

not

are affected,

block cabinet

power devices.

power

a

protector,

affect the

line not

power-line

Do

on

the problem.

Keyboard can ruin

power outlet.

and carefully

cotton

swab to clean

kit.

proper disk

out of alignment.

area that

home

is

Computers

it is better

vents

of

Computer. Try

used

by appliances

conditioner,

not switch

it. Immediately

Then, if circuitry

rinse

the Keyboard printed

between the keys.

connectors and

Drives

about once

head alignment.

transport.

If the disk drive

below

80 degrees

are not

any

to maintain

of the

Computer

to avoid

or other

or

non-interruptable power

power On and

after a spill occurs,

or

contacts.

month

a

A

sudden bump or jolt

Fahrenheit and free of

affected

by cigarette smoke

smoke-free

a

system; Computer,

these fluctuations by using

heavy current demand

supply

Off

frequently.

disconnect

contacts are

circuit

Use

a

or after

must

contaminated,

board with distilled

non-abrasive

100 hours usage.

to

contact

the

be transported,

Disk

place

area

the

Store

disks in their

handling

precautions usually found

PRINTERS

Carefully vacuum

cleaner.

blanket.

a

STATIC

Static

anti-static mats,

vironment.

not

Do

This can

ELECTRICITY

electricity discharge

MONITOR

an isolation

Use

some Monitors

the Monitor

when

preserve

pattern

the

should never

is being

glare-reduction

protective covers and

the Printer

oil the machine.

regularly.

cause components

can affect

sprays, tools

transformer

and materials,

with any

use a HOT chassis

left

be

changed periodically.

feature.

on the

Wipe surface

The oil will

to overheat

the

Monitor

(chassis

on for long

never

touch the disk

back of disk

collect abrasive

protective

areas clean

grit and dust.

and fail.

Computer. In order

and maintain

that

does

to

good humidity in

not

come

connected to one side

periods of

time at high brightness

Use caution when cleaning

surface. Observe

covers.

using

light

a

The dust will

minimize

as

of the AC line). The

the

possibility,

the

Computer en-

part of

the system

anti-glare screens,

the disk

all-purpose

act

as

use

since

face of

level except

to

Vtll

SAM

CM

cc
HI
i-

=5

CO

a.

CO

2

CO

o

o

CM

cc

o CO

T"

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o

to

o

CM

^

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111

<

a

X

o

(/)

s

o

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<

CC

in

T"

o

o

PRELIMINARY

Block Diagram

Disassembly

General Operating

GridTrace

IC Pinouts and

Line

Logic Chart

Miscellaneous

S

Location

Definitions

COMPUTERFACTS"

SERVICE

ENCLOSED

Instructions

Instructions

Guide

Terminal Guides

Adjustments

CHECKS

Page

24
25
25

3,22

17

15,16

25

INDEX

7

•nataie

-

:

^-'-;*;V-;^

SAFETY

Parts

List

Photos

Safety

Precautions

Schematic

Schematic

Test

Troubleshooting

Notes

Equipment

RADIO

SHACK COLOR

MODELS

mm

PRECAUTIONS

See

page 18.

26-3134,

11 thru

5,

6,19,20

2,4,21

8,9,10

COMPUTER 2

26-3136

o

o

oi

3J

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D

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C/>

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30

Page

14

18

23

8

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33

NS

SAMS

The listing of any available replacement

constitute in

Howard W. Sams

replacement part. The numbers of these parts have been compiled

from information furnished to Howard W. Sams

manufacturers

im

recommendation, warranty or guaranty

any case a

Inc.,

& Co.,

of

as

the particular type of replacement

Howard

4300 West 62nd Street, P.O.

to the quality and suitability of such

W.

part herein

& Co..

Sams

does

inc., by the

listed.

part

& Co.

not

by

Box 7092,

Reproduction or

content,

respect to the

© 1986 Howard W. Sams & Co.

4300 West 62nd

Printed in U.S. of America.

Indianapolis,

without express

use,

in any

manner,

use of

prohibited. No patent liability is assumed

is

the information contained herein.

Street, P.O. Sox 7092, Indianapolis, Indiana46206 USA.

Indiana 46206 U.S.A.

permission,

86CC14969 DATE

editorial or

of

pictorial

with

4-86

A

PHOTOFACT STANDARD

NOTATION

SCHEMATIC

w.THHEBffiQEBl

©

Howard W. Sams

&

Co.,

Inc.

1886

RADIO

SHACK

COLOR

COMPUTER

MODELS

26-3134, 26-3136

1C PiNOUTS &

TERMINAL

GUIDES

SC7752SP

5N74L5273N

CLEAR

^

~^y~

vc

V~j

N

n

2

is

ID

a

D

clear

CK

CLEAR

*

A

D

3

T

6

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C13

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IC10

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IC16

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TEST EQUIPMENT

Equipment listed

Test

measurements

and is compatible with most

by

Manufacturer illustrates typical or equivalent equipment

types used by

field service technicians.

used by SAMS'

Engineers

to obtain

TEST EQUIPMENT (COMPUTERFACTS

Equipment Name

)

Precision

B & K

Equipment No,

Sencore

Equipment No.

OSCILLOSCOPE 1570A,1590A,1596 SC61 454

PROBE DP51

LOGIC

PULSER DP101

LOGIC

DIGITAL VOM 2830

DVM37,DVM56,SC61

ANALOG VOM 277

ISOLATION TRANSFORMER TR110,1604,1653,1655 PR57

FREQUENCY COUNTER 1803,1805 FC71.SC61 710

COLOR BAR GENERATOR 1211A,1248,1251,1260 CG25.VA62 431

RGB GENERATOR

FUNCTION GENERATOR 3020

HI-VOLTAGE PROBE

1260

HV-44 HP200

VOM/DMM

Accessory probes

TEMPERATURE PROBE TP-28

CRT ANALYZER 467,470 CR70

COMPUTER DEAD

Disconnect all peripheral equipment from Computer except

the Monitor. Turn Computer On and check for proper

tion.

If Computer operates properly, turn Computer Off and

reconnect peripherals one

of Computer each time a peripheral is connected until the

peripheral causing the problem is found.

If

Computer does

not

disconnected, check for

voltage is missing, refer to the "Power Supply" section

this Troubleshooting guide. If the power supply

correct, check

Address lines (pins

missing

for pulses on Data lines (pins 24 thru

thru

at any of the pins, refer to the "Microprocessor

8

time. Recheck the

at a

operate properly with peripherals

pin

of CPU

of SALT

3

IC (IC9).

5.0V at

23)

Operation" section of this Troubleshooting

are present

at all of the pins, refer to the "Video" section.

POWER SUPPLY

Computer is

If the voltage at pin

voltage

at collector of Voltage Regulator Transistor

Q1 collector voltage is

drop across Resistor R2. If the voltage across

greater, the power supply may

down)

mode. Check Capacitors

shorts. Also check

be overloading the

approximately 1.0V, check Resistor

tion. If the

sistor

If voltage at the collector of

voltage across R2 is less than

and

Q1

approximately

If the voltage is missing, check

check

Power Transformer (T1) for

If the

17.5VAC is

check

Capacitors

for possible shorts.

Check for

dead.

of

3

IC1

least

at

for other shorted components

power supply. If

pin

5.0V at

is

than

less

7.5V, measure the voltage

in

be

the foldback (shut-

and

C5, C6

the

voltage across R2 is

R2 for

IC1.

is less than

Q1

17.5VAC between the anodes of

Power Switch (SW1). Also

possible open winding.

present,

and

C2

a

check Diodes

and the printed

C3

3 of SALT IC (IC1).

TROUBLESHOOTING

If 5.0V is present at pin

opera-

operation

(IC1).

IC

voltage

31)

If

pulses are

guide. If pulses

4.75V, measure

(Q1).

R2 is 0.2V or

for

C1 1

possible

that may

an

open condi-

check Tran-

0.2V,

7.5V, check for

and

D3

and

D3

D4.

circuit board

the

If

and

D4.

Also

-

andD2and

3

IC1.

excessive

If excessive 120Hz ripple is present, check Capacitor

excessive

and

of

is

MICROPROCESSOR

Computer is

to check the data lines (pins

there is no activity on the

the

the

Computer is turned

reading on pin

Switch (SW2) is pressed. If the

at

If

Capacitor

If the

(SW2)

Resistor

If the reset circuit is working properly, check for the

894.886KHZ E

IC9. If the clock pulses are missing, check the waveform

pin

If the waveform is missing

Capacitors C43 and

the waveform is present

E clock

are present at pins

Capacitors

pin

10V at

and

of

15

The

AC ripple should

and

C11

reset circuit

CPU IC (IC9). Pin

pin

of the

37

Power On reset works properly

does

R22

of the SAM (Synchronous Address Multiplexer)

6

pulses

Simpson

Equipment

463,467,470,474,467E

260-7,160,165,

260-6XL.260-7P,

No.

260-6XLP

420A.420D

248

00168,00411,00749

IR-10,00760,00758;

383,389,388

of

3

15 of IC1. If

Capacitor

IC1, use a scope to check for AC ripple at pin 3 of

-

If the voltages are normal

C1.

be

ripple

60Hz

150-200Hz

IC1.

is present,

ripple

check for approximately

IC1,

10V is missing, check Diodes

at

less than 0.4V peak-to-peak. If

check

Diodes D3 and

is present, check Capacitors

C2.

pins

OPERATION

dead, power supply checks good.

observing the

by

of the

37

24 thru 31

data

CPU

lines, check

logic

should

of

IC9)

the operation of

reading

beLow when

scope

Use a

for activity. If

pin

at

37 of

On and then immediately go High. The

37 should also be Low whenever the Reset

logic

reading

not correct

is

CPU when the Computer is turned On, check

Diodes

C48,

not work, check

and

Diodes

and

Q clock pulses at pins 34 and 35 of CPU

C44,

pins

at

13 and 14 of IC22. If the clock pulses

13

and

C37

C38.

D10, D11 and D12

Switch

and

D11

at pin

Resistor R15 and Trimmer TC1. If

pin

at

6 of IC22,

and

14 of IC22,

but

SW2,

D12.

%,

check

and

Resistor R20.

the

Reset Switch

Capacitor

check Crystal

for the Q and

check

IC22

C58,

IC22.

and

D1

D4.

If

C5

the

at

X1,

8

TROUBLESHOOTING

If the

E and

CPU

IC9,

In

addition,

60-Hz pulse

pin,

check

pin

having

If any

of the

TTL logic

check

possible shorts.

mally,

there may

device

of IC12)and

ty.

If signals

SAM

IC (IC22)

ed by observing

activity

check

Decoder

puts and outputs.

If pulses appear on

when the Computer is

check the RAM ICs (IC14 thru IC21), ROM IC (IC12)

pansion

VIDEO

clock

Q

check

for

pin

3

on it.

the

ICs

an

incorrect

address or

levels, check

the

other devices

be a processing

enable line.

the

PIA chip enable

are absent

by substitution.

with

lines

a scope. If the

IC (IC11) and

ROM IC (IC13).

pulses are

a logic

(IRQ

line)

If the

and other

If the

Check

50

the

data

turned On and then suddenly stop,

present

High

should

logic

reading

components

reading.

data lines

the

CPU IC9.

on the

address lines

the ROM

on either

The

through

SAM is

NAND

lines (pins 24 through 31 of IC9)

at

at pins

2, 3,

have

a short,

is

Also

check

are not

If the

address

or the

are functioning

problem

chip enable

line (pin

23

of these lines,

SAM can also

(pins

52

good,

gate IC10

pins

4 and

not

correct

connected

the

generating

due to a defective

of IC7) for

25, 26

use a scope to

34 and

CPU is

data bus for

for proper

35 of

40

of IC9.

low-going,

at any

to the

CPU

IC9.

valid

good,

nor-

line (pin

activi-

check

be check-

and

27)

and Ex-

20

the

for

in-

(Continued)

clock signal

4.0V peak-to-peak.

IC8,

check SAM

If the

and R13, check

and

10

waveform

put at pin
value in

missing,

modulator

If color is missing

IC

(IC4) and Switch

Colors are not correct.

signals

or incorrect,

and

Q2

correct. Incorrect

modulator.

ferent

Also check

should have

If the clock signal is missing

IC (IC22).

3.579MHz waveform is

the Phase

11 of the Video

is missing, check

of

9

the range of

check IC8.

that may

pins

at

The

IC8.

If IC8 is

be

in the high-resolution

Transistor

10 and 11 of

check

IC8. Also check Timer

associated components

colors may also

If the color on

shade than the rest

Capacitor

SOUND

No sound.

Type in and run

an amplitude of approximately

present

A and Phase

Display Generator

IC8. Also check the

CH

output should

B

0.5V to 2.0V. If the

good,

loading

the chroma signals

at

check

the

junction of

waveforms

B

(IC8). If either

be a steady

CH B output is

for

a

mode, check

(Q2).

Check the Phase

IC8. If either signal

if the Phase

A and Phase

IC4. Transistor

A

be caused by

the left side of the screen

of the screen, check

C26 and Resistor R10.

the following

Basic program.

at pin

at pins

CH B out-

possible

from IC8.

is missing

signal

defective

a

is a dif-

Timer IC4.

33

C61

DC

bad

Timer

in-

is

of

B

o
o

CJ1

30

>

No video. Check

Display

check for

is

good,

shooting

Generator

missing,

refer

5.0V

check

Guide. If the

the waveform

(ICS). If the waveform is

IC

at the junction of

Choke

the "Power Supply" section of this

to

for an open condition. If

L1

waveform is missing

check IC8. Also check Capacitor

ground.

If dots are missing from

the alphanumeric characters,

check Video Display Generator IC (IC8). If the

characters appear on the Monitor screen, check for pulses

at pins

2, 5, 6, 9, 12, 15,

missing at

at IC5, check IC8.

any

of the pins, check IC5. If pulses

and

16

pin

at

and

L1

C59

of Latch IC5. If pulses are

19

of the Video

28

the

If

C62.

pin 28 of IC8,

at

for possible

are present

present,

Trouble-

voltage

L1

short

wrong

to

VIDEO GRAPHICS

One or more of the graphics modes

and run the following program:

=

10 FORX

20 PMODEX:

30 NEXT X: GOTO 10

This program

graphics modes that are available. While the program is

running, check

Display Generator IC (IC8). If pulses are missing, check the

PIA (IC2) and the SAM (IC22). If

check IC22.

0TO4

SCREEN

for

X

continually switches between the five

pulses at

pins

do

27, 29,

the

pulses

not work. Type

and

30

of Video

35

are present,

COLOR

junction of

color.

No

and R13. If

C61

amplitude

and

R13

signal at

Check the

than lOOmV

of less

Capacitor

pin 33 of the

3.579MHz

the

C61.

Video

waveform at

waveform is

peak-to-peak,

check

Also

Display

for the

the

check

or has

Resistor

missing

3.579MHz

Generator (IC8).

an

clock

The

is

in

10 SOUND

This

itor speaker.

waveform
waveform is

IC3.

If

pulses are missing

(IC2).

check

pin

200,200: GOTO 10

program

in Figure

If pulses are

If the

the

modulator. Also

of IC3 and

1

produces

While

missing, check

a continuous sound from

the program is

1

pin

at

present

at

at pins

for pulses

pins

3 thru

output waveform is

check for

the sound

input of the modulator.

Figure

running, check

1 of DAC

3 thru

8 of IC3, check IC3.

8 of IC3, check

present at pin

continuity

1

IC (IC3). If the

at pins

KEYBOARD

Keyboard is

good connections. Also check

tween the Keyboard and the Main board. If the Keyboard

and

cable

pin

IC11. If pulses

(IC7).

joystick Connectors for possible

Connector CN2

11 of Decoder IC (IC11).

Also check Capacitors

Check the Keyboard Connector (CN2)

dead.

are present

for

broken flex cable

a

check

If pulses are missing, check

pin

at

C15

check for pulses at

good,

11 of

and

C18

shorts.

IC11, check PIA IC

the Mon-

for the

3 thru

PIA IC

1 of IC3,

between

on pin 4 of

8

for

be-

the

en

5

o

i

>

2

o

2

So

O

of

w

-<

r-

WO

2§

m

30

One

key is

of

keys

cable.

Keyboard
Keyboard

and

column

tinuity

ing the

row

or

Keyboard

the

Keyboard

check

Wrong

Check

good,

SERIAL

Output

nect

any

in and

10 POKE

POKE

20
30

GOTO 10

erratic or

do not

Also

cable

matrix

between

key.

common

and

PIA IC

character

the

Keyboard

check

I/O PORT

missing

equipment

run the

65312,2
65312,0

work,

check

on the

lines

the

If

a group of

cable

and

(IC7).

the

Main board

at

following

dead.

Connector

can

for an

two lines

line

common

are

cable and

appears

for

serial I/O

connected

Replace

check the

be

checked

schematic

inoperative

at

keys

defective,

on screen

possible

for

port

Basic

program.

TROUBLESHOOTING

the

Keyboard.

Keyboard

CN2.

by referring

diagram.

key and

Connector

are

inoperative,

to the

replace

Connector

when

shorts.

a possible

(Connector

to the

serial

The

defective

If the

If

and

Keyboard

Keyboard

Select

check

CN2

while

check

keys.

the

keyboard.

CN2 are

Key is

pressed.

Keyboard

short.

JK3). Discon-

I/O

port.

a group

to the

the row

for

press-

good,

Type

and

con-

the

If

If

is

(Continued)

Programs

following

itself

to the

10

CSAVE:

While

the

pulses

at pin

check

Connector

check

for

pulses

are

thru

5

Programs

to-peak

JK4.

wave

check

C23. If the

an

PIA

check

IC2.

JOYSTICK

of IC2,

9

1kHz

Check

at pin

Connector

approximately

IC (IC2).

IC3.

cannot

basic

cassette.

GOTO

program

17 of

pulses

missing,

cannot

square

for

of

11

waveform

If the

If the

be

saved

program.

10

is

DAC

JK4. If

at pins

check

replace

be

loaded from

wave

an

approximately

SALT

J

Resistors

K4,

is present

5V

peak-to-peak

waveform

waveform

to

This

running,

IC

pulses

5 thru

IC2.

IC3.

at pin

IC (IC1).

is

cassette.

program

use

(IC3).

are

missing

9 of PIA

If

pulses

cassette,

4 of

1V

If

the waveform

R4

and R23,

at pin

square

is

missing

present

Type in

continuously

a scope

If

pulses

at pin

IC

are

present

inject

Cassette

peak-to-peak

and

11 of

IC1, check

wave

at pin

pin

at

2

and

to

check

are

present,

17 of

(IC2).

a 4V

Connector

is missing,

Capacitor

at pin

2 of IC2,

of

IC2,

run

the

saves

for

IC3,

If

any

at pins

peak-

square

for

2 of

check

Check

for an

minimum

nector

JK3. If the

JK3, check for

square

and

Connector

of IC1,

portion

for

approximately

voltage

ply"

section of

voltage

of the

square wave

input

Serial

and check for

1 of JK3 to the

pin

of IC1. Pin

5

JK3 is connected

when

Low

If any of the

check

PIA IC(IC2).

approximately

amplitude

of

6

40Hz square wave

the

wave is

signal

present

at pin12of

JK3. If the

check

IC1. Also

of the

square wave

-10V at pin

is missing

is

present

pin

at pin

this

Troubleshooting

at pin

is missing,

does not

work. Ground pin

a logic High

volt source and

+ 5

4 of IC1 should

to ground and pin

of

2

is connected

JK3

above conditions are not

CASSETTE

Cassette motor

PIA IC (IC2). If the voltage

IC2. If the voltage

at pin

of

9

of IC1, check

check

SALT IC (IC1). If the voltage

Cassette Relay (RY1)

not turn

does

is correct

IC1. If the voltage is

40Hz square

volts

peak-to-peak

pin

at

12 of

IC1, check

square wave

check

PIA IC (IC2).

is missing

15 of

15 of

IC1, refer to the

15 of

at pin 5 of IC1. Next, connect pin

and

IC1

replace

check for

logic High

go

4 of IC1 should

wave

pin

at

is missing

SALT IC

is missing

If the

at pin

4 of JK3,

IC1. If the

"Power

Guide. If the

the

negative

IC1.

of

1

Connector JK3

logic

a

when pin

to the

5 volt source.

+

having

4 of

at pin 4 of

(IC1). If the

Resistor

at pin

negative

check

negative

negative

portibn

Low at

go

met, check IC1. Also

Off. Check for

at pin 39 is not

pin

at

39 of IC2, check for

for possible

correct at pin

0V at pin 39 of

correct, check

is not correct

9 of IC1,

sticking contacts.

at pin

Con-

Sup-

2

logic

5.0V

a

R3

12

of

9

Joysticks

program

10 FORX =

20N(X)

30 NEXT

not

do

to check the

0TO3

=

JOYSTK(X)

X

40 PRINT "RIGHT

PRINT

50
60

70 PRINT

80
90

100 FOR T=

The

joystick

to

63

appear for

number

Check

tions.

pins

or

pin

and

(IC11).

If

pulses are

pins

thru

of

9

and

"RIGHT

PRINT

"LEFT
"LEFT

PRINT "RIGHT

PRINT

"LEFT

1

numbers

horizontal

while

the

the

whenever

joystick

While running

and

19

39 of PIA

of IC7,

39

of IC7,

39

If

pulses

present

thru

9

of

IC2, check

of PIA

4

9

IC2, check

C17 at the

work.

operation

JOYSTICK

JOYSTICK
JOYSTICK
JOYSTICK

BUTTON

BUTTON =

TO

100: NEXT

that

appear

and

joystick is

joystick

the

Connectors

the

IC (IC7).

check

IC7. If

check

for

are missing

at pin

IC

(IC2). If

IC2.

IC3.

Also

joystick

Type in

and run

HORIZONTAL

VERTICALS;

HORIZONTAL

VERTICAL

= ";

";

(PEEK(65280)

T:CLS:

on the

vertical

positions

being

operated.

buttons

button is

JK1 and

above

program,

If pulses

pulses

pulses

at pin

10 of IC11,

pulses are

If

pulses are

check

connectors.

the following

of the

joysticks.

";

=

(PEEK(65280)

GOTO 10

Monitor

should vary

The

should

pressed.

JK2 for

check

are

missing

are present

at pin

10 of

10 of IC11,

check

missing

present

Capacitors

";

=

N(0)

N(1)

";

=

N(2)

N(3)

AND1)

AND2)

screen

for

from

numbers

change

to the

good connec-

for

pulses at

at pin

at pins

Decoder

check

for

pulses

at pins

at pins

C13,

4 thru

C14, C16

Basic

.

the

that

19

19

IC

IC11.

at

4

Cassette

ing

motor

will not turn

Basic program.

On. Type in and run the follow-

This program

motor.

10 POKE

After running

the

substitution.

for .1V
at pin

65313,60

voltage is not

the program, check

If the voltage

pin

at

9

of SALT

9

of IC1, check

correct

IC1, Relay RY1 and

pin

at

is correct

IC (IC1). If the voltage

10

turns On the

for

2.8V at PIA IC (IC2). If

39 of IC2, check

pin

at

39 of IC2, check

is not correct

Diode

D9.

cassette

IC2 by

Joystick

does

not

while

pressing

reading

rect

tions and

the

Low

the reading

rect

tions

is

at pin

left

joystick

at pin

at pin

and check

buttons

do not

work, check

the

correct,

check

of IC7,

3

check

the

pushbutton

of IC7

is correct,

of

IC7,

2

the

while

2

for

right

check

right

check

check

left

work.

a logic

joystick

IC7. If

Connector

joystick

does not

pressing

IC7.

Connector

joystick

If the

right

Low

at pin

pushbutton.

the logic

JK1

button

work, check

the left

If the

J K2 for good

button

joystick

3 of PIA

reading

for

good connec-

for

continuity.

joystick

reading

for

continuity.

button

IC (IC7)

If the

is not

for

a logic

button. If

is not

connec-

logic

cor-

If

cor-

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13

PARTS

When

ordering parts,

LIST AND

state

DESCRIPTION

Model,

Part Number,

(Continued)

and

Description

ELECTROLYTIC

ITEM

No.

C20

RATING

IOuF 16V

RESISTORS

ITEM

No.

R2

COILS &

ITEM

T2

LI

TRANSFORMERS

No.

CAPACITORS

HP CC106MDAP

2fi%

(Power

.01

Power

RF Choke

Metal Film N0001 EGE

5% 1W

FUNCTION

(IOOuH)

MFGR.

PART

No.

and Special)

RATING

(Sweep

Circuits)

MFGR.

PART

1056

ATA

ACA8339

CAPACITORS

ITEM

No.

C43

C44

TCI

PART No.

No.

24

24 NPO 50V

6-50

MFGR.

IDENTIFICATION

RATING

50V 5%

NPO

5%

REPLACEMENT

PART No.

1WD10

OTHER

NTE

CC240J

CC240JJCP

AC0988

DATA

NOTES

MFGR.

PART No.

JCP

WORKMAN

PART No.

MISCELLANEOUS

ITEM

No. PART

FB1

Thru

FB4

RY1 Relay

SI

Thru

S53

SW1 Switch

SW2

SW3 Switch

XI

(1

Number

)

CABINETS

Cabinet
Cabinet

PART NAME

Ferri te Bead

Switch

Sw i ten

Crystal

Foot

PC

Board 20261043

on

unit.

&

Top

Bottom

CABINET

ITEM

PARTS

AZ7134

AZ7135

AR8166

2900

AS

AS2849

AS2847

MX1112

AHC2450

(When

PART

MFGR.

No.

(1)

ordering

No.

Cassette

Key

Power
Reset

Channel

14.31818MHz

RUSSELL

(4 Required)

Main

specify

Industries

Knob,

Knob,

Replacement REC-2085

model, chassis

ITEM

Power

Reset

NOTES

&

color)

PART No.

AK5012

AK5638

14

LOGIC

CHART

PIN

NO.

1

2

3

4

5

6

7

8

9

10

11

12

13
14

15 P 15

16

17 17

18 18

19

IC

IC1

H

H 2

H 3

H

H

H 6
L 7

L 8

9

H

L 10
L 11

P 12

L
L

H

20

PIN

IC PIN IC PIN IC

NO.

IC8 NO. IC8

1

L 21 P 1

2

P 22

3

P 23 P 3

4 P 24

5

6

7 P 27

8

9

10

11 P

12

25

P
P 26

P 28

29

L

P 30

31

P 32 P 12

PIN

IC PIN IC PIN

NO.

IC2 NO. IC2 NO. IC3 IC4 IC5

1

4

5

13

14

16

19

20

'

21

L
L
H
L

L

L

L

L 28 P 8

L

H

*

H

L 33 P 13
L

L

L

L
H 38
L
H

P 1

22

H

23

H

24

H

25 P 5

P

26
27 P

29

P 9

30 P

31 P 11

32 P 12

34

H

35

P
P

36

37

H

H

39

L

40

H

2
3

4

6

7

10

14

15

16

17
18

19

20

IC IC IC IC PIN

*
L

L L P P 3

L

L L

L L
L L P P 7
L H P

H

L L L

L P
L

*
*
*

#

*

H H H 20

PIN IC PIN

NO. IC9 NO. IC9

21

P 2

P 4

P 5 P 25 P 5

P

L 7

L

L

L
L 11 P 31 P 11 P

L
H

P 23 P 3 P P 3 P 15 P

*

6

L

H

8

P 28 P 8

9

P

10 P

P 32

P 1 P

22

P 2

24

P 4

P

26

27 P 7

29

P

30 P 10

P

IC

IC7 NO. IC7

L 21 P

H
H
H

H
H

H

H

H

P 30

P

P

P 33

P

L

H

P

P P 2

P P 4

L

P
P P

P

P P

P

P P 14

IC6 NO.

P 1

P

P

P

5

6

8

9

P

P 13

10

11

12

P P 15 P 35

P"

P 16

P P 17

P

P 37 P

P P 18 P 38

P P

NO. IC10 1

IC IC PIN

'

6

9

P 1 P 13 P

P P 2 P 14

P 4 P 16

H

L P 5 P 17 P

L H

L P

L L

L H

H H 10

P 11

12

P

H

19

NO. IC12 NO. IC12

C1

6 P 18

7

8

9

L
H

IC

P
P 20

P 21 P
P
P

12

L

PIN

22

23 P

24

25

26
27

28

29 P

31 P

32

34

36

39
40 P

PIN

19 P

22 P
23 P
24

IC

H

H

P
P
P
P

P

P

P

H

P
P

P

L

IC

P

P

P

P

H

>
D

o

=:

to

o

o

>

m

o

r-

*

C/)

ro

o

o>

O

w

r~

O

CO

JC»

30

o

N>

OJ

o

CO

2

"O

co

c

o>

H
m

33

13

P 33

14

P 34 P 14

15 P 35

16

P 36

17

H 37

18

P 38

19

20

39

P
P 40

P 17 P 37

13 P 33

P 34

15

L

P 16

P 35 P 15
P

P 18 P 38 P

P

19

L

20 P 40

P

P
P

36

P 16 H

H

39

L

H

13 P

14

17

18

19

20

P

P

H

P

1

15

LOGIC CHART (Continued)

PIN IC

NO.

1 P 13 P 1

2 P

3 P 15 P 3 P P P P P P P P
4 P 16 P 4

5

6 P 18 P 6 P P P

7

8 P

9

10

11

12

13

14

15 15 P P P P P P P P

16

PIN IC

NO.

1

2 P

3

4

5 P 25 P

6 P

7 P

8 P

PIN

13 NO.

14

17

p

P

19 P 7 P P P P P P P P

20

21

P

22 P 10 P P P P P P P

P

23

P

24

L

PIN

22

NO.

P 21 P

22 P
P 23 P
P 24 P

26

27 P

28 P

PIN

IC

13

NO.

2 P P P P P P P P

P

P

5

P

IC

IC

14

*

*

P

IC IC IC IC IC IC

15

16 17 18

*

* * * * *

19

P P P P

P P P P P P P P

P P P

8

P

P

P

H

IC

H H H H

9 P

11

P

12 P P P P P P P P

13

P P

14

P P P P

16

L

P

P P

L

P P

P P

L

H

P P

P P P

P P
P

L L L

H H

P

22

P

20 21

P

P

P

P

P
P

L

P

P

H

P

P
P

P
P

L

9 P 29 P

10 P

11 P 31 P

12 P 32 P

13 P 33 P

14 P 34 P

15 P 35 P

16

17 P 37 P

18
19 P 39 P

20

Logic Probe

=

Low

L

=

High

H

Pulse

P=

=

*

Open (No

Logic probe

Note:

On, no keys

30

P 36 P

P 38

40

L

Display

light On)

readings

pressed,

P

P

H

taken with

unless otherwise

computer turned

noted.

16

LINE DEFINITIONS

A0THRUA15

CART

CAS

MOT

CASS

CASSDIN

CD

CTS

DO THRU D7

DAO

E

EN1

Clock, 1/16 Master Clock, CPU RAM

EN2

Fast Interrupt Request, Does

FIRQ .

FS

H1

HALT

HI/LO

Joystick Reference Level, X and Y

Cartridge

Column

Cassette Data

Status Interrupt

Cartridge Select Signal

Display Address Zero

ROM Expansion

Not Maintain Registers

Chip Select, PIA

HS

IRQ .

JOY THRU JOY 3

MAO THRU MA7
MDO THRU MD7

NMI

PIAO

PIA1

Q

R/W

RAS

Peripheral Interface Adapter Zero

Peripheral Interface

Leads E

Nonmaskable

Clock, 1/16

Clock

'.

".

Row

RESET

RSOUT1

RS232
RS232 IN RS232

SCS

Spare Cartridge Signal, Selects

SEL1.SEL2 PIA

SLENB Select

Transistor/Transistor Logic Input

RS232

Interface System Input

Select Outputs, Joysticks

Enable, Disables Internal Selection,

SND Sound

V CLK

VDG CLK Video Display

WE

Address

Presence Interrupt

Address Strobe

Cassette

Input (RS232C)

Halt

Horizontal Sync

Interrupt Request

.Joystick

Motor

Input

Addressing

Enable

ROM

Enable

Sync

Field

and CS1

CSO

Input

CPU

Inputs

Data

Axis

»

Memory Address

Memory Data

2

o

O

j2

^

So

"
g 2

"^

2

<*>

3D

g,

O

en

x

>

O

p-

™
q

^

Interrupt

Adapter One

Master Clock,

Degrees

Ninety

by

Read/Write

Address Strobe

for RS232C Output

Interface System

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Utilities

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SAFETY

PRECAUTIONS

1. Use an isolation

2. Maintain

3. Remove

typical

4.

Use extreme caution when handling

static

ly available

Use

Use an

Do

Do

The

10. Instructions should

cabinet.

11. Never

water

12. Never leave

outlet during

AC

AC power from

ES

electricity.

a grounded-tip, low

isolation (times

not remove

not

use freon-propelled

Computer

This could

expose the Computer

sources.

transformer

line

voltage

devices

are integrated

Drain off any

discharging

install

or

cabinet

is

be given,

cause shock or

the Computer

lightning storms.

for

servicing.

at rated

the

wrist strap

voltage soldering iron.

10)

board,

equipped with

input.

Computer before

circuits and

the printed

electrostatic charge

device. This should

probe on

sprays.

scope.

floppy

These

especially

disk

vents

to children, that

can generate electrical

equipment

to water. If exposed

unattended or

plugged

servicing

semiconductor

circuit

drives, printers, or other

or installing

boards. Some

on your

body

be

"chip"

by

removed prior

charges sufficient

to prevent heat

build-up. Never

objects should

damage.

to water, turn

into

the

the unit off.

AC outlet for

electrostatically

components.

semiconductor

touching

peripherals with

known

a

to applying

block, cover,

not

dropped

be

Do not place

long periods of

sensitive

devices

earth ground.

power

devices.

can

be

damaged

Wear a commercial-

to the unit

Examples

under

power On.

to damage

time. Remove AC plug from

semiconductor

or obstruct these,

or pushed into the

the Computer near

easily by

test.

devices.

vents.

vents of

possible

of

the

AC

13.

Never

use

sure the Computer is

liquids

or aerosols

directly on the

disconnected from

Computer. Spray

the AC

power line.

on cloth

and then apply

to the

Computer

cabinet.

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SCHEMATIC MOTES

-#—

Circuitry
Circuitry

e

See

-Jr Ground

**»

Chassis

Common tie point

^

Waveforms

Voltages, Waveforms and Logic

not

used

list

parts

otherwise.

used

and voltages taken from ground, unless noted

computer turned On,

noted.

Waveforms taken

switch in Calibrate position,

coupling on

input to view waveforms after DC reference is measured

when

necessary. Each

reference voltage given

form.

in

Time

ftsec.

some versions

in

in some

with triggered

reference

per cm,

versions

probe readings taken with

no

keys pressed, unless otherwise

scope and Sweep/Time

input

scope

waveforms.

voltage

waveform is

the bottom

at

given with

7 cm. width with DC

line

reading

p-p

each waveform.

Item

numbers

justment

voltages maintained

Supply

Voltages measured

Controls

Terminal identification may not

Capacitors are

Electrolytic capacitors are

noted.

Resistors are

Value In

Measurements with switching

in rectangles

instructions.

adjusted

50

%W

used

)

(

with

digital meter, no

for normal

volts or less,

or less,

in

5% unless noted.

some versions.

appear in

as shown

operation.

be

at input.

found

5% unless noted.

volts or

50

shown,

as

the

signal.

on unit.

less,

unless noted.

set for

DC

Switch to AC

of each wave-

the end of

at

alignment/ad-

20% unless

Logic Probe Display

=

L

Low

=

H

High

P =

Pulse

*

=Open (No light On)

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DIAGRAM

24

DISASSEMBLY

INSTRUCTIONS

CABINET

Remove six

Computer right

MAIN BOARD

Carefully disconnect

remove

CASSETTE

REMOVAL

Phillips screws from

side

up

and

REMOVAL

Keyboard. Unplug

OPERATION

keyboard

cabinet

bottom.

remove cover.

from

cable

Main board and

Power Transformer

GENERAL

Turn

from Main

OPERATING

Connect a cassette recorder to the Cassette Socket (JK4) on

the Computer using the

Plug the black plug on the cable into the Earphone

large gray plug into the Auxiliary

into the Remote On/Off

cable furnished with the Computer.

jack

on the Recorder.

jack

and

the small gray plug

Jack,

the

To load a program from cassette, put the Recorder in Play

mode with the volume turned about half way

CLOAD

pear on the

the program. When the Computer finds the

ter F will appear on the screen and the word

after the program has been loaded.

To save

Record mode. Type CSAVE and then press the Return key.

and

then press the Return key. The letter

Monitor screen while

program

a

to cassette, put

the

Computer searches for

the Recorder in

program, the let-

OK

Type

up.

S will ap-

will appear

the

board.

cabinet

tom of Main

board.

POWER TRANSFORMER

Unplug

Phillips screws holding

Remove

base

six Phillips screws holding

and

remove board. Remove

board

removing

by

Power Transformer

Power

17 clips that attach it

REMOVAL

from Main

Transformer

Main board

shield from bot-

to the

board. Remove two

cabinet

to

base.

to

INSTRUCTIONS

The word OK will

gram has been saved

appear on the Monitor

and the Recorder

POWER UP

The Computer will come

with no cartridge in the slot. If

Computer

will come up

RESET

The Computer will be Reset

(SW2) located on right rear of cabinet.

BASIC

PROGRAMS

A

Basic program in the Computer RAM can

ing RUN and then pressing the ENTER key. The program can

stopped

be

pressing

by

in Basic mode when turned On

up

running

by

the BREAK key

screen after the pro-

will shut Off.

cartridge is installed, the

a

program in the

the

pressing the Reset button

or

the Reset button.

be

cartridge.

started

by

typ-

CLOCK ADJUST

Connect the input of

(IC22). Adjust

3.579545MHz.

RF MODULATOR

Connect Computer to

the Clock Trimmer (TC1) for a

frequency

a

TV

a

MISCELLANEOUS

counter to pin 7 of SAM IC

frequency of

Monitor. Set the TV and the

ADJUSTMENTS

Channel Select Switch

the following

SOUND

10

Adjust the Channel

just the sound coil for best

the TV and

Adjust the

program:

200,200: GOTO10

the Channel Select Switch

Channel

(SW3)

Coil for

4

Trimmer

3

to Channel

best picture and sound.

sound

4. Type in and run

with

minimum noise.

SW3 to Channel

for best picture and

Ad-

Set

3.

sound.

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