Cromemco 3100 User manual

Crorneineo

3100

&

3101

TERMINAL

Part

no.

023-0077

SERVICE

MANUAL

CROMEMCO,

Inc.

280

Bernardo

Avenue

Mountain

View.

CA

94043

March

1980

This

document

has

been

prepared

by

Beehive

International

and

is

furnished

on

the

condition

that

it

will

be

used

by

tha

customer

solely

for

the

purpose

of

supporting

the

operation,

service

and

maintenance

of

Beehive

products.

The

rights

of

the

customer

with

respect

to

this

document

will

be

governed

by

mutually

acceptable

provisions

of

the

contract

with

Beehive

International.

This

document

shall

not

be

duplicated

by

the

customer,

nor

released, disclosed

or

used, in

whole

or

in

part,

for

any

purpose

other

than

stated

herein,

without

the express

written

permission

of

said Beehive

International.

Section

4.1

4.2

4.2.1

4.2.2

4.2.3

4.2.4

4.3

4.3.1

4.3.2

4.3.3

4.3.4

4.3.5

4.3.6

4.3.7

4.3,8

4.3.9

4.3.10

4.3.11

4.3.12

4.3.13

4.3.14

4.3.15

4.3.16

5.1

5.2

5.2.1

5.3

5.3.1

5.3.2

5.3.3

5.4

5.5

5.5.1

5.5.2

5.5.3

5.5.4

5.5.5

8150

MAINTENANCE

MANUAL

TABLE

OF CONTENTS

Title

SECTION

IV

-

THEORY

OF OPERATION

INTRODUCTION

GENERAL

FUNCTION DESCRIPTION

Power Supply .

Monitor

Keyboard.

Logic Board.

DETAILED

FUNCTIONAL

DESCRIPTION

Power Supply .

Monitor

Vertical Synchornization. .

Horizont.al Synchronization

Video Information .

Keyboard.

Display Organization

Cursor Location Counter

Memory

Character Generator

Video

Shift

Register

Input/Output

Operations UART (Receiver) .

UART (Transmit) .

Block

Send

Circuit .

Auxiliary

Send

Circuit

Special Function (F1-F16)

SECTION V -

MAINTENANCE

INTRODUCTION

PREVENTIVE

MAINTENANCE.

Troubleshooting Equipment

CORRECTIVE

MAINTENANCE

Troubleshooting Preliminary Considerations.

Troubleshooting

Flow

Diagrams .

Full/Duplex Echoplex

Test.

MONITOR ADJUSTMENTS

DISASSEMBLY PROCEDURE

Case

Removal .

Logic Board Removal .

Keyboard Assembly.

Fan

Removal

Monitor

Assembly Removal.

iii

Page

4-1

4-6

"4-6

4-6

4-7

4-11

4-12

5-1

5-2

5-17

5-18

Section

Title

Page

SECTION

VI

-DRAWINGS/SCHEMATICS

APPENDICES

A MONITOR

1 General Information A-1

2 Theory

of

Operation

A-1

3 Preliminary Adjustments . A-6

4 Troubleshooting and Maintenance A-9

B GLOSSARY

c PROGRAMMABLE LOGIC

ARRAY

INPUTS

TABLES

Table Description

Page

5-1

Troubleshooting

Flow

Diagram. Index. . . .

5-3

ff

FIGURES

Figure Description

Page

4-1

Basic

Block Diagram 4-2

4-2

Basic

Functional Flow Diagram

4-3

Basic

Functional Flow Diagram 4-4

4-4 Power Supply Block Diagram . 4-5

4-5

Character

Dot

Matrix

4-8

4-6

Timing Diagram 4-9

4-7

Timing Diagram 4-10

5-1

Echoplex Test Connector

5-2

Monitor

Adjustments

5-17

5-3

Assembly Drawing

5-19

A-1

Voltage Waveform A-10

A-2 Interconnecting Cabling Diagram

A-11

A-3 Circuit Board Components Location A-11

A-4 TV5, 9 and

12

Without

Power Supply A-12

iv

SECTION

IV

Theory

of

Operation

4.1

INTRODUCTION

This section

contains

the

theory

of

operation

for

the

BEEHIVE

8150

Terminal. This discussion

is

presented

as

a functional description

at

a detailed

block diagram level referencing

appropriate

func-

tional blocks

on

the

diagrams.

4.2

GENERAL FUNCTIONAL DESCRIPTION

The

B

150

consists

of

four

basic functional

compo-

nents, Power Supply, Mani

tor,

Keyboard

and Main Logic Board. Figure

4-3

shows

the

basic

functional flow diagram

of

the

terminal. These

functions

are briefly described

in

the

following

paragraphs.

4.2.1 Power

Supply

The Power

Supply

provides

the

required, regula-

ted

DC

voltages

to

the

terminal. This assembly

will

operate

on

100, 115,

or

230

V

AC

50/60

Hz

power (see Section

II).

·

4.2.2

Monitor

The Monitor Assembly includes a 12 inch (30.5

cm). diagonally measured,

CRT

and its

support-

ing solid-state circuitry.

The

Monitor

is

controlled

by

the

vertical

and

horizontal

synchronization

sig-

nals, and the video signals generated on

the

logic

board. A full screen

of

information

consists

of

24

4-1

lines

of

80

characters and a

one

raster scan

bet·

ween lines. Brightness and

contrast

adjustments

ai-e

provided by external

potentiometers

located

on

the

rear panel, (see Figure

2-2,

Se~tion

11

).

Other

monitor

adjustments are discussed

in

Section V and in Appendix

A-.

4.2.3 Keyboard

The

keyboard

is

the

input

device used

by

the

opera-

tor

to

communicate

with

the

terminal. The key-

board

contains

the switches and

supporting

circuitry

to

generate

the

appropriate

control

signals and

ASCII codes utilized

in

the

B

150

terminal.

The

key-

board

conforms

to

the

proposed ANSI

keyboard

standard

for

data

keys,

but

has been

expanded

to

facilitate

the

capabilities

of

the

8150.

4.2.4 Logic Board

The

Logic Board contains

the

major function and

control circuits in

the

B150 termina. It also

holds all

of

the

DC

voltage regulators

to

power

the

unit, with

the

exception

of

the

+5 V regulator.

The

basic operations accomplished by

the

main

logic board are: Generation

of

data

a!1d

control

signal~

for

the

monitor,

interaction with

the

key-

board,

control

of

the

data

sent

between

the

B

150

and any external device, and generation

of

the

basic timing signals essential for

the

operation

of

the

terminal.

VllJl::O

L:UH.'>0)1

~~~~~~

liENEAATION

Ul'UftL

HUH"Ef!E:O

TORli!:MOTE

r.~~=-"'\..---

MONJTOR

VIUSD

CURSOR

"DFF

SCffEiSN"

CIRCUIT

CHC

KBYEIOA.ftD

CONTROL

WCilC

Figure 4-1 BASIC BLOCK DIAGRAM

FROM

KEYBOARD

"-<V'''

~<?'''

"-<?''"

N

H C U

\ y

~

GO

TO

"LF"

GO

TO

"ADV"

r;o

TO

"llKSP"

Figure 4-2 BASIC FUNCTIONAL FLOW

DIAGRAM

au

TO

"flTN cunson"

Figure 4-3 BASIC

FUNCTIONAL

FLOW

DIAGRAM

RECTIFIER

·"'

TRANSFORMER

"'

115/230vAC INPUT BLOCK

RECTIFIER

FIGURE

4-4

POWER

SUPPLY BLOCK

DIAGRAM

+5

v

REGULATOR

+15

REGULATOR

+12

REGULATOR

-12v

REGULATOR

+5vDC

+15

vDC

+12

voe·

-12

vDC

4.3

DETAILED FUNCTIONAL DESCRIPTION

A detailed discussion

of

the

BEE HIVE

8150

termi-

nal

operation

is

contained

in

the

following para-

graphs. The Subassembly

components

of

the

termi-

nal are functionally

interdependent,

however,

the

isolation

of

various functions

to

the

responsible

subassembly

is

relatively simple.

The

function

of

each subassembly

is

also described.

Schematic

diagrams are provided in Section

VI

of

this

manual.

4.3.1 Power Supply

The

Power

Supply

provides +5, +15, +12,

and

-12

voe voltages

to

the

circuitry from a

115

or

230

VAC source

at

50

or

60

Hz.

Figure 4-4

is

a

block

diagram

of

the

Power

Supply

subassembly.

The

DC

regulators utilized are overcurrent

and

ther-

mally

protected.

The

power

applied

to

the

Power Supply

is

step-

ped

down

in voltage.

The

transformer

output

voltages are rectified by

three

bridge circuits.

The

output

from

the

rectifiers

and

filters

pro-

vides

power

to

the

+5, +15, +12,

and-12

voe

regulator circuits.

4.3.2

Monitor

The

monitor

displays

data

on

the

CRT

in

a

pattern

determined

by

the

vertical

and

horizontal syn-

chronization

signals,

and

the

video

information

driving signals. A

+15

VDe

voltage

is

applied

by

the

Power

supply

to

the

Monitor.

Appendix

A

presents general

and

detailed

data

on

the

Moni-

tor

Assembly.

4.3.3

Vertical

Synchronization

Vertical

synchronization

is

applied

to

the

verti·

cal oscillator

and

triggers it

at

the

vertical

re-

fresh rate

determined

by

the

driving logic.

The

vertical frequency

is

stabilized by

the

vertical

frequency

control,

which

determines

the

point

of

oscillation.

The

output

pulse

of

the

vertical

oscillator

is

applied

to

the

driver amplifier

which shapes

the

pulse

and

is

controlled

by

the

vertical linearity

control.

The

output

of

the

driver amplifier

is

applied

to

the

vertical

driver by way

of

the

height

control.

The

verti-

cal driver

output

pulse

is

applied

to

the

yoke

of

the

CRT

and

causes vertical deflection.

The

refresh rate

is

50

-

60

Hz. switch selectable.

4-6

4.3.4

Horizontal

Synchronization

The

horizontal synchronization pulses are applied

to

the

horizontal amplifier where

they

are ampli-

fied and applied

to

the horizontal driver.

The

out-

put

of

the horizontal drive

is

applied through

the

width

coil

to

the

yoke, where

it

causes

the

horizon-

tal deflection.

The

horizontal deflection signal

is

also applied

to

the

flyback trano;former.

Tt-ie

hori-

zontal deflection signal

is

stepped

up

to

approxi-

mately 12

KV

where it

is

then

rectified, filtered

and applied

to

the

anode

cap

of

the

CRT

to

pro-

vide

the

high voltage required.

4.3.5

Video

Information

The

Video Information

is

applied

to

the

vick:o

amp·

lifier by

way

of

the

contrast

r.ontrol,

external

to

the

monitor.

The

video

information

siqnal

irom

the

video amplifier

is

appiied

to

the

cathode

of the

CRT

gun

to

cause

an

On/Off

condition

corresponding

to

light

patterns

of

the

screem.

The

brightness con-

trol

is

external

to

the

monitor

and

varies

the

vol-

tage

on

the

accelerating grid

of

the

CRT.

4.3.6

Keyboard

The

keyboard

is

compatible

with

ANSI

standards.

Section

111

defines

the

ASCII

codes

available

and

shows

the

keyboard

layout.

The

keyboard

enables

the

operator

to

manually

input

information

to

the

terminal. When a key

is

depressed,

the

keyboard

logic generates

the

corres-

ponding

7-bit

ASCII

code

and presents

the

c!ata

in parallel

form

to

the

keyboard

data

lines.

After

a

short

delay

for

debouncing,

the

strobe

is

driven

to

its active level and held

there

as

long

as

the

key

is

held

down.

For:

those keys which

auto

repeat,

the

strobe

line

is

pulsed

at

a 15

character

per

second

rate.

The

BREAK key

is

not

encoded.

but

is

a func-

tion

line

that

is

driven low for

approximately

400

millisee,onds when

the

key

is

depressed.The follow-

ing keys cause special

8-bit

(non-ASCII) codes:

AUX SEND, l ,--.,._,

t,

CLEAR/HOME.SEND,

EOS, EOL,

and

DELETE CHAR.

These

codes

are

used internal

to

the

CRT

only

and

are

not

transmitted.

4.3.

7 Display Organization

The

main timing

rhain

(oscillator,

dot

position

counter,

character

position

counter,

character

height

counter,

and

character

line cciunter)

defines

the

configuration

of

the

display

on

the

CAT.

There

are

27

lines, 3

of

which are used

for

vertical

retrace and

24

of

which are used

to

display charac·

ters.

The

27

lines are

composed

of

ten

scans each.

Each scan being

composed

of

7 x

10

dot

matrix

field which

contains

a 5 x 7

character

matrix

for

the

displayed character.

Oscillator

The

oscillator

is

crystal

controlled

with

a

frequency

of

10.8864

MHz.

Two

74H04's

are

connected

in series by a

100pf

capacitor.

Each

74H04

has a 1 Kohm feedback resistor

around

it.

A

10.8864

MHz crystal

is

connected

from

the

input

of

the

first

74H04

to

the

output

of

the

second.

The

output

of

the

oscillator

is

buffered,

inverted

and

fed

to

the

Dot

Position

Counter.

Dot

Position

Counter

This divide-by-seven coun-

ter

defines each

of

the

seven

dots

required

to

compose

one

character.

The

outputs

of

this

four

stage

counter

are labeled DPC1, DPC2, DPC4,

and DPC8.

The

Counter

actually presets

to

a

count

of

10,

counts

up through

the

overflow

point

at

15

to

a

count

of

zero,

and

presets

then

back

to

a

count

of

10.

The

Dot

Position coun-

ter

output,

DPC8, drives

the

Character Position

Counter.

Character Position

Counter

The

Character

Position

Counter

is

composed

of

two

binary-

type

counters

that

define

96

character

times,

each being seven

dots

wide.

The

output

of

the

Character Position

Counter

drives

the

Charac-

ter

Height

Counter.

Character Height

Counter

The

Character Height

Counter

is

a standard

counter

that

defines 10

scans

of

96 characters each,

with

each charac-

ter

being seven

dots

wide.

The

output

of

the

Character Height

Counter

drives

the

Character

Line Counter.

Character Line

Counter

The

Character

Line

Counter

is

a binary

counter

that

starts

at

a

count

of

zero

and

counts

to

a

maximum

of

26

for a total

of

27

character

lines.

The

final out-

put

of

this

counter

runs

at

the

vertical refresh

rate.

Horizontal

and

Vertical Drive

The

Horizontal

4-7

Drive is

started

when

the

Character Position Coun-

ter

leaves

the

video area

of

the

scan and

is

active

for

the

following

40

character

times.

The

high

active

output

of

this

flip-flop

is

sent

to

the

moni-

tor

on

pin 9

of

connector

J 1.

The

vertical drive

is

generated during

the

time

that

the

Character Line

Counter

is

decoding 24.

4.3.8

Cursor Location

Counter

The

Cursor Location

Counter

identifies

the

loca·

tion

of

the

cursor. This

is

a

count

made

from

the

Cursor Line

Counter,

called CURL, and

the

Cur-

sor Position

Counter,

called CURP. These

two

counters,

in

conjunction

with

the

ROLL

counter,

are used

to

address

the

memory

to

determine

the

entry

point

of

the

The

cursor

loca-

tion

counters

are

compared

with

the

The

cursor

location

counters

are

compared

with

the

Character Position

Counter

and

the

Character

Line

Counter

to

generate

the

signal called CNTR

CURSOR. This signal

is

used

to

generate

the

cur-

sor displayed

on

the

CRT. Also associated

with

the

cursor

location

counters

is

the

appropriate

circuitry

to

move

the

cursor

up,

down,

right, left,

home,etc.

A LINE FEED

code

causes

the

Cursor Line

Counter

to

increment

by one. A

CARRIAGE

RETURN

code

clears

the

Cursor Position

Counter.

With

the

terminal operating

in

FORMAT MODE,

when

the

cursor

is

incremented

off

the

bottom

line,

the

cursor

automatically

wraps

around

to

the

top

of

the

display, i.e;,

the

Cursor Line

Counter

is

reset

to

zero. However, if

the

terminal

is

not

in

FORMAT MODE,

the

display scrolls whenever

the

cursor

increments from a

count

of

23.

A scroll

is

initiated by any

of

3

functions

if act-

ivated when

the

cursor

is

on

the

last· I

in

e

of

the

display and

the

terminal

is

not

in FORMAT MODE:

a.

LINE

FEED

or

CTRL

J

b. CURSOR

DOWN

or

ESC B

c. If

the

cursor

is

on

the

last position

of

the

last line.

1.

Cursor right

2. Any displayable

character

3. Space

DOT ft

BLANK

DOT

0

rOTO

DOT S

ILANIC

CHARACTER

BLANK

CHARACTER

BLANK

L DISPLAY

,·

L

DISPLAY

'l

A. A

SCAN 0

ir.O

0 0 0 0 0 0 0 0 0 0 0 0 0

0 • 0 0 0 • 0 0 • • • • • 0

0 • 0 0 0 • 0 0 • 0 0 0 0 0

CHARACTER 0 • • • • • 0 0 • • • • 0 0

DISPLAY

0 • 0 0 0 • 0 0 • 0 0 0 0 0

SCAN

8

ir.O

0 0 0 0 0 0 0 0 0 0 0 0 0

-

SCAN 9

•0

• • •

•••

0 0 0 0 0 0 0 0

F'OR

CURSOR

SCAN 0

.o

0 0 0 0 0 0 0 0 0 0 0 0 0

0 • • • • • 0 0 • 0 0 0 • 0

0 • 0 0 0 0 0 0 • 0 0 0 • 0

CHARACTER 0 • • • • 0 0 0 • • • • • 0

DISPLAY

0 • 0 0 0 0 0 0 • 0 0 0 • 0

SCAN 8

•0

0 0 0 0 0 0 0 0 0 0 0 0 0

SCAN 9 ..0 0 0 0 0 0 0 0 0 0 0 0 0 0

FOR

CURSOR

FIGURE 4-5

CHARACTER DOT

MATRIX

4-8

osc

OPC1

DPC2

DPC4

DPC8

""

CPCI

'°

CPC2

CPC4

CPC8

CPC16

CPC32

CPC64

CPC80

~"/

FREQ=

10.8864

MHz

DOT

POSITION

COUNTER

FREQ=

1.5552

MHz

CHARACTER

POSITION

COUNTER

FIGURE 4·6 TIMING DIAGRAM

CHC1

CHC2

CHC4

CHCB

CLC2

CLC4

CLCB

-!'

0 CLC16

CLC32

FIGURE

4-7

TIMING

DIAGRAM

CHARACTER HEIGHT

COUNTER

FREQ.=

1.800 KHz

CHARACTER LINE

COUNTER

(50

Hz

OPERATION)

FRE0=60Hz

CHARACTER LINE

COUN'fER

(60

Hz

OPERATION)

11

3.9

Memory

.1e

page memory

is

actually a

2048

byte

memory.

Each byte consists

of

9 bits: 7 for data,

one

for

protect,

and

one

for

blink. Of these

2048

bytes,

1920

are displayable. The program does

not

have

the

capability

of

displaying

or

writing

into

the

remaining 128.

In

order

to

write

data

into

the

page memory from

the

receiver, the

memory

address

is

muxed

over

to

the

cursor

location

registers and

the

signal WRITE

is

generated.

The

UART

is

then reset and

is

capable

of

receiving

the

The

page memory

output

is

sent

to

the

character

generator

input

buffer

at the

proper

time

to

generate the displayable

characters. The program has

the

capability

of

shutting down

the

screen refresh

for

any given

operation

to

increase

the

program operating

time.

4.3.10

Character

Generator

The Character Generator

is

a read-only

memory

(ROM)

that

is

addressed by

the

character

(in

ASCt

I).

The

scan configuration and

the

charac-

ter

indicates

the

pattern

desired

on

that

scan.

e-bit

dot

patterns

are generated which form

.•

ortion

of

a character.

The

output

of

the

character generator

is

applied

to

the

parallel-

to-serial video

shift

register.

~.3.11

Video

Shift

Register

The

parallel-to-serial Video

Shift

Register

is

loaded with

data

by

the

tow-active signal, DPC8,

and

is

clocked by

the

main oscillator

output.

The

dots

are shifted

out,

mixed with cursor informa-

tion,

and blanking signals, and applied

to

the

monitor

through

the

CONTRAST

control

as

video information.

4.3.12

Input/Output

Operations UART (Receiver)

Data can be received by the B150 from

one

of

three

sources; from

the

two

t/O interfaces into

the

receive side

of

the

UART

or

from

the

keyboard

through

the

transmit

side of

the

UART

to

the

receive side

of

the

UART.

The

UART

is

driven by a clock generated inter-

nally off

the

main

counter

chain. No separate

n"cillator

is

required. A rotary switch located

4-11

on

the

back panel switches the clock rate for

operation from 75 to

19200

baud.

The

times 16

clock

is

then

applied

to

the

transmitter

and

re-

ceiver

of

the

UART.

The EIA line receiver receives

data

at

RS

232C

levels and gates

them

into

the

UART

when

the

B

150

is

on-tine. Through

the

same gating, data

is

brought

in from

the

transmit

side

of

the

UART.

The

data

is

brought

into

the

UART where

it

is

converted

to

parallel (seven bits) data.

4.3.13

UART (Transmit)

The

keyboard

data

lines for bits 1

through

7 are

applied

to

the

transmit

input

data

lines along with

the

seven BUS lines. Also coming

from

the

key-

board

circuit

is

a load signal which triggers

the

UART

to

initiate the transmission.

As

the

UART

receives

the

character

for transmission, it performs

the

appropriate

parity generation, provides

one

or

two

stop bits; divides

the

X16 clock

to

get

the

baud

rate, and transmits

the

character.

The.character

is

applied

through

an EIA

RS

232C

interface

to

the

computer

or

modem.

Also coming from

the

UART

is

output

data

at

a TTL level which

is

applied to

the

receiver side

of

the UART through

the

previously

mentioned

logic.

The

EIA interface includes a Data

Terminal Ready signal which indicates

the

status

of

the

B

150

to

the

computer

and a Request

to

Send

signal which indicates

that

the

terminal has

data

to

send

to

the

computer.

The

Clear-to-Send tine coming

from

the

computer

is

monitored

at

the

EIA

RS

232C

interface levels. It

is

received by a line receiver w·hich

converts it

to

TTL

levels and applies

it

to

the

UART

clock

control

circuit

to

control

transmission. An

optional times 8 clock (TTL levels)

is

available

as

part

of

the

interface.

The

BREAK key

is

on

the

key-

board and enables a

timer

which

holds

the

transmit

data

line in a spacing

condition

for a

predetermined

length

of

time.

4.3.14

Block

Send

Circuit

The

Block Send feature allows

the

operator

to

com-

pose a message

on

the

terminal screen and

then,

by depressing

the

SEND key, cause

the

terminal

to

send

the

entire

message

to

the

computer

at

the

selec-

ted

baud

rate.

The sequence

of

operations

is

described

in

Figure 4-1.

The operation

is

as follows:

1.

Raise Request-to-Send .

2.

When Clear-to-Send, send STX (002)

header.

3.

Send data

4.

If

FORMAT and END

OF

PROTECTED

FIELD,

send

HT

code

(11

la)

5.

If

not

FORMAT and

END

of

LINE.

send CR/LF sequence.

(0159/0129)

6. When

end

of

message, send

ETX

(0038)

7. Time

out

and drop Request-to-Send.

4.3.15 Auxiliary Send Circuit

The Aux Send feature

is

identical

to

the Block

Send except for two points:

1.

The message

is

transmitted

out

the

AUX

Port instead of the

Main'l/0

Port.

4-12

2.

The

delimiters

sent

at

the

start

of

mes-

sage, end

of

unprotected

field, end

of

line, and ETX are selected from a dif-

ferent

portion

of

the

Block

Send

ROM.

4.3.16 Special Function (F1-F16)

Sends a code sequence

to

the computer from the

terminal. The code

is

instigated by pressing any one

of the 16 function keys.

1.

An STX

is

transmitted (0029)

2.

An

Escape code (0339)

3. Code character

(see

ASCII

Code Chart

Table 3-2)

4. And ends with an

ETX

(0038)

SECTION

V

Maintenance

5.1

INTRODUCTION

This section contains

information

to

aid

in

the

maintenance

of

the B

150

Terminal. Preventive

and corrective maintenance procedures are

specified

as

well

as

troubleshooting aids and

techniques.

5.2

PREVENTIVE

MAINTENANCE

No scheduled periodic maintenance

is

required.

However, several precautions

can

be

taken

periodically

to

ensure proper operation. Care

should

be

exercised

to

see

that

there

is

proper

air

circulation

for

the fan. The terminal should

not

be

placed on a

shag

carpet

or

other

soft

sur-

face

that

could impede the air entrance

to

the

fan. Special care must

be

taken

to

ensure

that

no paper or

other

loose articles

are

placed under

the terminal. The degree

of

dust density in the

air should

be

considered in selecting

the

location

of

the terminal.

The

interior

of

the

unit

may

be

wiped free

of

dust.

Accumulation

of

dirt

causes

overheating and

component

breakdown.

Dirt

acts

as

an

insulating

blanket

and prevents

efficient

heat dissipa1ion. A

small brush

is

very useful

for

dislodging

dirt;

;:i cot-

ton-tipped

applicator

is

good

for

narrow

or

hard

to

get places.

The

following

is

a list

of

the troubleshooting aids

that

are

provided in this manual

to

assist

in the

troubleshooting

of

functional

failures.

5-1

Circuit

Schematics

Detailed

Block

Diagram

Functional

Flow

Diagram

Timing

Diaqrams

Glossary

of

Terms

Troubleshooting

Flow

Diagrams

DisassemblyI

Assembly

procedures

Adjustment

Procedures

Configuration/Strapping

Power

Supply

Adjustments

Character

Dot

Matrix

See

Section

VI

{Figures 1, 2, & 3

of

Section

IV

See

Section

IV

Appendix

B

This

Section

This

Section

See

Section

11

See

Section

11

See

Section

IV

5.2.1

Troubleshooting

Equipment

The

following

is

a list

of

tools and standard equip-

ment

required

to

repair a

B150Terminal:

V

/0

Multimeter

Oscilloscope

Assorted Electronic Hand Tools

5.3

CORRECTIVE

MAINTENANCE

This section provides corrective maintenance

information

to

aid in servicing the B

150

Terminal.

It

is

suggested

tht

the

configuration

sheet and the

turn-on procedure

be

consulted before

performing

the corrective maintenance described here

(see

Section

111).

5.3.1 Troubleshooting Preliminary Considerations

The most

common

probl-em occuring in

8150

are

switch,

control

and operation related. A simple

procedure may

be

followed

to

help determine

if

the problem

is

control

and/or

operation-related

or internal

circuitry

related by checking the

following:

IIlegal Operation (Refer

to

Section

11)

Improper Baud Rate Setting

Wrong

Transmit

or

Receive Mode

Loose

Interconnect

Cable

5.3.2 Troubleshooting

Flow

Diagrams

A

list

of

troubleshooting

flow

diagrams is given

in

Table

5-1.

This

index

lists

apparent

failure

and

refers

the

user

to

the

proper

flow

diagram.

The

Table

is

only

intended

to

allow

the

user

to

verify

the

subassembly

where

trouble

exists and

not

to

indicate

the

specific

problem.

The

user

is

ad-

vised

to

return

the

defective

subassembly and

have

that

subassembly repaired

or

replaced

by

an

authorized

service agent.

1.

Find

the

apparent

trouble

in the

Trou-

bleshooting

Flow

Diagram Index.

2.

Proceed

to

the specified

Troubleshoot-

ing

Flow

Diagram in the diagram section

and begin the troubleshooting procedure.

3.

If

an

adjustment

procedure

is

referen-

ced

in the

Troubleshooting

Flow

Diagram,

perform

the

adjustment and

return

to

the

flow

diagram

to

complete the trouble-

shooting process.

4. Reference

is

made

to

Timing

diagrams

contained in (Section

VI)

this manual.

5.3.3

Full-Duplex

Echoplex Test

A specially

wired

connector

may

be

assembled

that

will

allow

the

operator

to

perform

this test.

This

connector

tester allows the terminal

to

be

operated and tested independent

of

an

external

data device.

The

connector

mates

with

the Main

1/0 Port. Set-up

for

the test

is

as

follows:

FOX

(Full

Duplex

Mode)

Baud Rate

--

Any

Setting

Test

Connector

Installed

in the

1/0

Port

5-2

Enter data

from

the keyboard

as

you

would

if

you

were on-line

to

a computer.

If

data

is

dis-

played on the screen

properly,

then the B150

is

transmitting

and receiving data

properly.

The Test Connector

is

wired

as

follows:

(Refer

to

Figure 5.1.)

Connects Transmitted Data Line

out

of

the terminal

to

received data line

into

the

terminal. Pin 2

to

Pin 3

of

the

1/0

Port.

<ID

• •

Pin 3 _

...

•

Pin 2 •

•

Jumper

between

Pin 2

and

Pin 3

<JD

Male

Type

Amphenol

Connector

Beehive Part No.

606-0011-25

AP

Figure

5-1

ECHOPLEX

TEST

CONNECTOR

Table 5-1. Troubleshooting Flow Diagram Index

Apparent Failure

GENERAL

No

raster present

No

raster present

Troubleshooting

Flow Diagram

5-1A

5-1

B

1---------------------------------1---------·---!I

OFF

LINE

Cursor either absent,

multiple

cursors, cursor

not

in home

position

or

screen

filled

with

video blocks

No character displayed when

written,

non cursor advance

Wrong character displayed

No

escape

functions

No

control

functions

ON

LINE

No

data being

transmitted

Transmits invalid data

No

reception

Receives invalid data

and/or

improper

parity

DISPLAY

All

displayed characters

out

of

focus

Rolling

display

Display

too

tall/short

for

screen size

Height

of

displayed characters uneven

Display

too

wide/narrow

for

screen size

Display

not

centered

Tilted

display

Others

A.

B.

C.

0.

E.

F.

G.

Single vertical line

Physical damage

Dot

in center

of

screen

Uneven

intensity/focus

Burned phosphor

Uneven display dimensions

Excessive

H.V.

A.rcing

5-3

5-2A

5-28

5

2C

5-20

5-2E

----

5-3A

5-38

5-3C

5-30

·-·--a

5-4A

5-48

5-4C

5-40

5-4E

5-4F

5-4G

5-4H

START

YES

REPLACE

MONITOR

NO

PLUG

IN

KEYBOARD

ADJUST

BRIGHTNESS

CONTROL

AT

REAR

OF

UNIT

PLUG

MONITOR

IN

REPLACE

WIRING

HARNESS

FROM

LOGIC

CARD

TO

MONITOR

REPLACE

LOGIC

CARD

5-4

NO

REPLACE

BOARD

END

5-1A

ENO

Cromemco 3100 User manual

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