Boss Audio Systems BV8.5GA User Manual download pdf (Page 80)

MAC'S SERVICE

SHOP

The

Simplest

Test

Gear

HEY, Mac,

what

are you do-

ing

with

the tattle

lights

Barney

asked

his employer,

who

was

examining

several

small objects

spread

out on the

service

bench.

"Taking

them

with me

vacation,"

Mac

replied.

"Some

of the folks

Florida

we visit

are

sure to

say, `Mac,

our electric

or electronic

what -

chamacallit

isn't

working. Wonder

you'll look

at it.' These

lights

will let

find

anything

simple,

which

all

in-

tend

to tackle

on vacation.

Actually,

it's

amazing

what

fellow

can

do with

some

simple, rugged,

inexpensive

test

lights

and

a little

gray matter."

"For

instance

"Well, take this Ne

-O -Lite

Test Light

put out by

GC Electronics,

a division

Hydrometals,

Inc., Rockford,

III. It

car-

ries

Audiotex

catalogue

No. 30 -245

Calectro No.

-452

and

sells for just

under

buck. As

you

can

see, it con-

sists

of a special

two

-inch -long,

red,

high- impact

plastic

socket

carrying

neon

bulb protected

tough

clear

plastic

cone

one

end. A

current -

limiting

resistor

-I'd

guess

-about

200,000

ohms is

contained

the

socket, and red

and black

flexible,

sharp

-pointed

leads

come out the

bot-

tom. The

lamp glows

with

any voltage

from

90 to

550 volts,

ac or dc. The

higher the

voltage,

the

brighter the

glow.

"The

neon lamp

itself

has

almost in-

finite resistance

until the

contained

gas

ionized

by over 90 volts.

Until

then,

there's

no voltage

drop

across

the

series

resistor,

the full voltage

across the

test leads is

applied to the

lamp.

Once

the

gas is ionized

voltage

excess

of 90

current

through

the lamp

and series resistor

function

of the voltage

across the

leads,

but it never

exceeds 3 mA,

even

with the full

550 volts

applied.

"What

can you

do with it ?"

"A zillion things.

one lead is

at-

tached

a spark plug

of a

running

motor,

a bright flash

will indicate

good plug;

a dim flash,

a fouled

plug;

and no flash,

a dead plug.

Hold

on to

John T. Frye,

W9EGV

one test

lead

and probe the

two

sides

of a

120

-volt

outlet

receptacle

with

the

other.

When you

touch the

'hot'

side of

the line,

the lamp will glow.

a device

controlled

wall

switch will not

turn

on and you

don't know if

the trou-

ble lies in the

device

or the

switch, turn

the

switch

on and bridge the

test lamp

across the

switch

terminals.

If the

lamp

glows,

the

switch is

bad.

the

same thing to locate

a blown fuse.

With

a device

the

fused

line

switched on, check

across

the fuse

with the

lamp. If it glows,

the

fuse is

open. Alternately,

you

can check from

the

grounded

side

the line

the

cabinet

of the fuse

box to the

output

sides of the fuses,

one at a time. Fail-

ure

the lamp

glow with full 120

-V

brilliance

will indicate

the

bad fuse.

"This

little

sketch

shows how

the

test lamp

can be

used

for

continuity

IRON

EXTENSION

CORD

TESTER

indicator.

Plug

extension

cord into

a wall receptacle

and locate

the

hot

side

the

cube tap

on the

end of the

cord. Plug

one lamp lead

into

this

side.

Now

plug

one prong

of the

cord

the

device

you

want to test

for

continuity

into

the

other, grounded,

side

the

cube

tap. Touch

the free lamp

test

lead

the free

prong

the

line cord

of the

device. A glow

of the

lamp indicates

continuity.

"The

test light

will indicate

the

pres-

ence

leakage

current. As

you know,

one

side of

the 117 -volt

line

grounded. If there's

current leakage

from the

hot

side of

the line

to the case

of a

device,

say a hedge- trimmer,

elec-

tric drill, refrigerator,

dishwasher,

etc.,

a person touching the device

while in

contact with the ground

or a grounded

device may

receive

a severe

and

perhaps fatal

shock.

With

a clip lead,

connect

one

side of

the

test lamp to

good

ground,

such as a water faucet,

and touch the

other lead to

the case

the device

being tested

while the

de-

vice is

operating. Reverse

the

plug

the device

in the wall

socket

and test

again. If

the

lamp

glows

in either

case,

you know

there'ssome leakage.

It may

not

exceed 0.5 mA through

1500

ohms

of noninductive resistance

shunted

0.15 µF,

which

represents

the

average

impedance

of the human

body

and the

current is

considered permissible

for

most devices;

but if

the lamp glows

full 120

-V brilliance,

you can

be sus-

picious. In

all the

devices I

checked

home,

only the electric

drill,

some fif-

teen years

old,

lit the

light dimly."

"What's

this thing ?" Barney

asked,

picking

up a

small

round

plastic

object

with three

prongs

on one end to

fit a

standard 15 -A, 120 -V grounding

re-

ceptacle.

"That's

a GT -20

'Grounded

Outlet'

Tester

made

by Alco Electronic

Prod-

ucts, 1551

Osgood

Street, North

An-

dover,

Mass.

01845.

sells, in

single

lots, for $7.95

and reveals

instantly

if a

receptacle

into

which

it is

plugged has

current

available

and is

properly

and

safely wired. Note

the three

little

round

windows

in the

end. Two

of them,

labelled

NEUTRAL

and POWER,

are

amber,

and the

bottom

one, labelled

DANGER,

POLARITY

is red. When

the

-20

plugged into

a grounding

re-

ceptacle,

one or more

of the lights

be-

hind the

windows light

if power

available

at the

socket. If the

socket is

correctly

wired,

the two

amber

win-

dows

glow. Any

other combination

lights

indicates

a potentially

danger-

ous receptacle

that

is improperly

wired

or has

a broken

connection.

"What's inside

the

thing ?"

"Not

being like

the little

boy

who

cut

open his

drum to find

what made

the

noise, I

didn't take

it apart to

see; but

I'd

guess

there

are three neon

lamps

with

accompanying

current -limiting

resistors,

each

wired between

a pair

prongs. Can you

figure

out which

lamp is wired

between

which prongs

produce

the conditions

shown in

the little

charts

"Child's play!" Barney

scoffed.

"Will it work

2 -hole

outlets

"The Code requires

that, in

all

new

construction,

only

grounding

recep-

tacles may

installed. If

you replace

a defective receptacle

an existing

88 POPULAR

ELECTRONICS

1 2 ... 75 76 77 78 79 80 81 82 83 84 85 ... 101 102

Comments to this Manuals

No comments

Boss Audio Systems BV8.5GA User Manual Page 80

Comments to this Manuals

Related products and manuals for Car video systems Boss Audio Systems BV8.5GA