Creative Engineering ROCK-A-FIRE EXPLOSION - Page 247

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B.

Controller

Problems

General

Information

If

possible,

try

to

isolate

the

problem

to

one

drawer

or

another,

by

determining

which

characters

are

responding

incorrectly.

This

will

allow

you

to

exchange

the

equipment

in

the

drawers

to

facilitate

locating

the

exact

problem.

Show

Control

Board

Locate

the

bit

on

the

Long

Driver

Board

that

activates

the

control

in

question

and

attach

your

O'scope

probe

to

the

collector

leg

of

the

transistor,

see

the

bit

chart

(pages

5-037

thru

5-064)

for

more

information.

Now,

back

the

tape

up

to

just

before

the

control

bit

is

activated

and

then

run

it

forward

again

as

you

watch

the

O'scope,

to

see

if

the

transistor

switches

the

voltage

from

5

volts

D.C.

high

to

low.

If

it

does

not

switch

then

exchange

the

driver

board

with

another

one

and

see

if

that

takes

care

of

the

problem.

If

that

does

solve

it,

then

replace

the

driver

board

or

repair

it.

Take

a

reading

on

the

finger

contacts

of

the

Show

Control

Board

where

that

control

is

found.

Show

Control

Board

Finger

Contact

Pin

Outs:

Deck 1

Deck 2

Function

Pin

Function

Pin

Stop

""E

Stop

--y;-

Play

D

Play

K

Rewind

c Rewind J

The

voltage

should

switch

from

high

to

low

as

the

signal

is

processed.

If

it

does

not

change,

then

the

board

may

be

bad,

so

pull

the

board

out

of

the

card

holder.

Now,

take

a

jumper

and

ground

one

end

as

you

touch

the

other

end

to

the

pin,

and

see

if

that

causes

it

to

function.

If

it

works,

then

the

board

is

bad

•

If

that

does

not

work

then

trace

the

signal

back

from

the

Dual

P.C.

mount

to

the

Tunnel

thru

the

wiring

and

out

the

Tunnel,

all

the

way

back

to

the

Remote

cables.

Then

you

can

unplug

the

Remote

cable

from

the

J13

Interface

and

bridge

the

pins

to

see

if

the

cable

is

bad.

You

may

also

exchange

the

cables

and

see

if

that

takes

care

of

it.

You

may

want

to

go

back

and

retrace

some

of

your

steps

if

the

problem

has

not

been

isolated.

Power

Supplies

As

a

matter

of

routine

trouble-shooting

procedures

you

should

check

your

power

supplies

early

in

your

procedure.

Examine

the

5v.

and

25v.

lights

on

the

Playback

Boards.

The

top

LED

is

for

25

volts

and

the

middle

one

is

for

the

5

volts.

The

bottom

LED

indicates

the

sync. Don't

forget

however,

that

the

LED's

for

the

voltage

do

not

necessarily

indicate

exact

voltage

but

rather

just

the

presence

of

some

voltage,

so

it

would

be

a

good

idea

to

double

5-o04