Simpson 260 series 5M User manual

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2

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PANEL

METERS

by

MODELS

27,

37,

47,

57

3~"

RECTANGULAR

A

CCUR

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:

2~

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'7. MODELS

25,35,

45,

55

SIMPSON

MODERNISTIC

3!"

ROUND.

A

CC

URAC

Y

2~

·CLEAR·VUE-

SC

ALE

LEN

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1-7

/8"

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AS MODELS 125, 135

BU

ILT

TO S

PE

C

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ORDER

145 AND 155 -ALL

2!"

2P.

3P.

It!".

5!"

SIZ

ES

ROUND

.

SC

ALE

1-7

/8

"

MODELS

27,

37.57

ILLUMINATE

D

3!"

REC

TANG

ULAR

A

CCU

RAC

Y:

2$

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MODELS 127, 137, 147,

MODELS

29,39,49,59

157.

2!"

RE

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ANG

UL

AR

It!"

RECTANGULAR

A

CCUR

A

CY

:

2$

A

CCUR

A

CY

: 2$

SC

ALE

LENGTH:

3-29/32"

SCALE

LENG

TH:

1-7/8"

NEA

RLY

800

DIFFERENT

S I

ZES

AN

D

KINDS

OF S IMP

SON

PANEL METERS

ARE

AVAILABLE

F

RO

M YO

UR

ELEC

TRONIC

PARTS

JOBBER.

WHETHER

YOU

NEED

ONE

PANEL

METE R

•••••

OR A DOZEN

•••••

LOOK

FOR

THE

FAMI

LIAR

OR

AN

GE

COLORED S

IMP

SO

N

BOX

.

FOR

FURTHER INFORMATION WRITE SIMPSON

ELECTRIC

CO

••

5200

W.

KIN ZI E ST• •

CH

I CA

GO

Itlt.

I

LL

••

ESTEBROOK

9-1121.

-~

OPERATOR'S

MANUAL

VOI.,..oHM-MlLLIAMME'I'ER

MODEL 260

SIMPSON

ELECTRIC

COMPANY

5200

W.

KINZIE

ST.,

CHICAGO

44,

ILLINOIS.

EStabrook

9.1121

IN

CANADA,

BACH·SIMPSON,

LTD.,

LON

DOH,

ONTARIO

Copyright

1955.

Simpson

El

ec

tric

Co

.•

Print

ed

in

U.S.A.

T

ABLE

OF

CONTENTS

SECTION

III

FUNCTIONING

OF

PARTS

Schematic

Diagram

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

.

D.C.

Volcmeter

Circuit

-

20,000

Ohms

Per

Volt.

Resistance

of Multiplier

Resistors

...•....

A.C.

Voltmeter

Circuit

-1000 Ohms

Per

Volt.

A.C.

Rectified

by

Copper

Oxide

Rectifier.

A.F.

Output Meter

...

Reading

A.C.

Voltage

Effective

Resistance.

2.5 Volt

Range

.......

.

Volume

Level

Meter.

Conversion

of

Scale.

Output

Meter

....

.

D.C.

Ohmmeter

...

.

D.c.

Milliammeter and

Ammeter.

SECTION

IV

MAINTENANCE

Do

Not Drop Your 260

..........

.

Make

Proper

Settings

Before

Use

..

.

Battery

Replacement

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

.

Pointer

Won't

Zero

on Rx1 and

RxlOO

Ranges.

Pointer

Won't

Zero

on Rx10,000 Range.

How to

Replace

Batceries.

Parts

List

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

.

SECTION

V

MODEL

260

SPECIFIC

APPLICATIONS

General.

..........

.

Measuring Grid

Currents.

F .M. Alignment

.....

.

A.V.C. Diode

Circuits.

High

Mu

Plate

Voltage.

20

20

20

21

21

22

22

23

23

23

24

24

24

25

27

27

27

28

28

28

32

34

34

34

34

35

T

ABLE

OF

CONTENTS

Bias

of

Power

Detector

......

.

Model 260

as

a

Condenser

Tester.

Initial

Deflection Not

Present

...

Positive

Jack

to

Positive

Condenser

Terminal

Should

Read

About.

5 Megohm

.....

.

Paper

Condensers

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

.

Condensers

From

.001

Mfd.

to 1.0

Mfd.

Descriptive

Tables

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

.

SECTION

VI

SUPPLEMENTARY

DATA

RMA

Resistor

Color

Code

Chart

.....

RMA

Mica

Capacitor

Color

Code

Chart.

RMA

Condenser

Marking

Code

...

Volts-Decibels

Conversion

Table.

Capacitive

Reactances.

Audio

Frequencies.

Radio

Frequencies

..

35

35

35

36

36

36

37

38

39

40

41

42

44

44

44

')

4

Fig.

1

Fig.

2

Fig.

3

Fig.

4

Fig.

5

Fig.

6

Fig.

7

Fig.

Sa

Fig.

8b

Fig.

9

Fig.

lOa

Fig.

lOb

Fig.

11

Fig.

12

Fig.

13

6

LIST

OF

ILLUSTRATIONS

Simpson

Volt-Ohm-Milliammeter

Model 260

Simplified

D.C.

Volcmeter

Circuit.

Simplified

A.C.

Voltmeter

Circuit

......

Simplified

Output

Meter

Circuit

........

Ohmmeter

Circuit

with

Selector

Switch

in

Position

Rx 1

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

Ohmmeter

Circuit

with

Selector

Switch

in

Position

Rx 100

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

Ohmmeter

Circuit

with

Selector

Switch

in

Position

RxlO,OOO

.......

.

...

Simplified

Microammeter

Circuit

....

Simplified

Milliammeter

and

Ammeter

Circuit.

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

.

Model 260

Schematic

Diagram

......

Model 260

Parts

Layout

-

Rear

View

..

Model

260

Parts

Layout

-

Rear

View of

Front

Panel

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

Model 260

Used

as

Condenser

Tester

....

RMA

Resistor

Color

Code

Chart

.......

RMA

Mica

Capacitor

Color

Code

Chart

...

PAGE

2

21

22

23

24

25

25

26

26

29

30

31

37

39

40

f¥oJWW-oJUI

WORLD

FAMOUS

As

the

purchaser

of a

Simpson

260,

you

are

now

the

owner

of

the

most

famous

testing

instrument

in

the

world. Com-

pact,

of

unusually

high

sensitivity

(50

microamperes

full

scale),

the

Model 260

has

earned

its

top

ranking

reputation

as

the

result

of

quality

construction

joined

to

exceptional

engineering

versatility.

This

engineering

superiority

is,

in

turn,

the

product

of

invaluable

years

of

experience

with

every

single

unit

comprising

the

complete

assembly.

. In

choosing

the

Simpson

260, you

have

concurred

in

the

verdict

of

over

300

governme

nt

agencies

and

university

laboratories

which,

long

before

World

War

II,

and

all

through

it,

purchased

it.

in

quantities

un-

equalled

by

any

competitive

instrument.

Ie

served

on

every

batdefront

and

in

every

branch

of our

armed

service

s.

MANY

FEATURES

IN

"260"

In

no

other

instrument

of

its

kind

do

you

find

features

such

as

are

contained

in

the

Simpson

Model 260. Ics trim,

scien-

tific

appearance

--

the

4];i"

modernistic

instrument,

the

heavy

bakelite

case,

the

neat

bakelite

.

panel

--

gives

evi-

dence

of

inner

quality.

These

hidden

features

are

too nu-

merous

to

mention

here,

but your

pride

in

your new

instru-

ment

will

grow

as

you

learn

of

them.

Parts

are

assembled

and

placed

in

position

so

they

cannot

become

loose

or

detached

from

their

original

positions.

All

the

sub-assem-

blies

are

mounted on

specially

designed

bakelite

pane

ls,

or on a

specially

designed

sub-panel,

made

and

engineered

expressly

for a

specific

function

in

the

Model 260.

7

SIMPSON

BUILDS

ITS

OWN

TEST

EQUIPMENT

When you

purchase

Simpson

test

equipmenr,

you

get

equip-

menr made

almost

enrirely

within

the

various

planrs

of

our

Company.

Each

component

pan

of

the

260

has

been

de-

signed

and

completely

rooled

and

manufactured

in

our own

planrs,

with

the

exception

of

the

resistors

and

one

or two

other

functionally

less

important

parts.

The

Model 260,

like

all

other

Simpson

testers,

is

not

an

assembly

job

made

up from

purchased

pans

such

as

is

true

of

the

majority

of

testers

offered on

the

market.

We

are

by

far

more

self-conrained

than

any

other

manufac-

turer

of

test

equipmenr.

This

is

your

assurance

that

the

testers

we offer

will

not

quickly

become

obsolete.

Our

tremendous

investmenr

in

expensive

production

rools

is

your

safeguard

against

obsolescence

and

further

assurance

of

unvarying

quality.

Here

at

Simpson

we do not

think

of making

instrumenrs

merely

to

sell.

We

think

of

making

instrumenrs

ro

serve.

Our

inrerest

in

your

Model 260

and

in

your

satisfaction

with

it

never

ceases.

That

is

the

reason

for

this

Operator's

Manual.

We

want

you to know how to

get

the

most from

your

260.

The

Model 260

is

a

rugged

instrumenr

and

will

withstand

a

great

deal

of

abuse.

We

urge you,

however,

to

treat

it

with

care

as

its

mechanism

is

actually

more

delicate

than

that

of

a

watch.

If

you

will

keep

it

clean,

free

from

conrinuous

severe

vibration

and

avoid

dropping

it,

your

Model 260

will

give

you

a

lifetime

of

accurate,

dependable

service.

OPERATOR'S

MANUAL

SIMPSON

MODEL

260

YOLT·OHM·MILLIAMMETER

SECTION

I

GENERAL

DESCRIPTION

The

Simpson

Volr-Ohm-Milliammeter

Model 260 offers

the

service

dealer

a

small,

compact

and

complete

instrument

with

high

sensitivity

for

testing

and

locating

trouble

in

all

types

of

circuits.

The

large

four and

one-half

inch

meter

provides

a

long

scale

that

is

easy

to

read,

and

the

compact

arrangemenr

of

the

conrrols

allows

the

overall

size

of

the

bakelite

housing

ro be

comparatively

small

for maximum

portability.

Each

unit

is

supplied

with

an

operator's

manual and

one

set

of

red

and

black

test

leads

with

insulated

clips.

The

electrical

circuit

is

designed

to

give

maximum

insur-

ance

against

inaccuracy

and

damage

to

the

componenr

pans.

Highly

accurate

carbofilm

resistors

are

used

ro in-

sure

long

life

and

dependability,

and

these

are

firmly

held

in

place

in a

special

bakelite

housing

designed

for

this

purpose.

The

entire

assembly

is

truly

rugged

and

can

well

withstand

the

wear

and

tear

of

the

service

work for

which

it

is

designed.

ACCURACY

Accuracy

is

3%

D.C.

and

5%

A.C.

of

full

scale

deflection.

8 9

GENERAL

DESCRIPTION

MEASUREMENT

RANGES

D.

C.

VOLT

AGE

0-2.5

voles

0-10

voles

0-50

voles

0-250

voles 20,000

ohms

per

vole

sensieiviey

o-1000 voles

0-5000

voles

A.

C.

VOLTAGE

0-2.5

voles

0-10

voles

0-50

voles

1,000

ohms

per

vole

sensieiviey

0-250

voles

0-

1000

voles

0-5000

voles

A.

F.

OUTPUT

VOLTAGE

0-2.5

voles

0-10

voles

0-50

voles

0.1

Mfd.

internal

series

condenser

0-250

volts

0-1000

voles

VOLUME

LEVEL

IN

DECIBELS

-12

co

+ 3

decibels

o

co

+

15

decibels

Calibrated

for

reference

level

+14

to

+29

decibels

of 500 ohms

and

.006

Wacts

+28

co

+43

decibels

+40

to

+55

decibels

10

GENERAL

DESCRIPTION

D.

C.

RESISTANCE

0-2000

ohms (12

ohms

cencer)

0-200,000

ohms (1200 ohms

cencer)

0-20

megohms (120,000 ohms

cencer)

CURRENT

IN

D.

C

CI

RCUITS

100

microamperes

10

milliamperes

100

milliamperes

250

millivoles

500

mi

lliamperes

10

amperes

D.

C.

VOLT

AGE

MEAS

UREME

NTS

D.

C. vole

age

is

measured

by

applying

ehe unknown

volcage

co

ehe meeer ehrough

suieable

ineernal

series

resiseors.

The

meeer

has

a

full

scale

sensieiviey

of 50

microamperes

ae

100

millivolcs

wieh

an

incernal

resiseance

of 2,000

ohms,

giving

ehe inserumenc

an

overall

sensieiviey

of 20,000 ohms

per

vole.

A.

C.

VOLTAGE

MEASUREMENTS

A.

C.

voleage

measuremencs,

including

oueput

and

decibel

readings,

are

made

possible

by

ehe

use

of an

incernal

cop-

per

oxide

receifier

conneceed

in

series

wieh ehe meeer. A

precision

wound

incernal

shunt

resiseor

is

conneceed

in

parallel

wieh ehe meeer in

order

co

obeain

a

sensieiviey

of

1,000

ohms

per

vole.

D.

C.

RESISTANCE

MEASUREMENTS

D. C.

resiseance

measuremencs

are

made

by

employing

an

ineernal

bactery

and

precision

series

and

shune

resistors,

resulcing

in

accuraee

indicaeion

of

resiseance

values.

11

GENERAL

DESCRIPTION

CURRENT

MEASUREMENTS

IN

D.

C.

CIRCUITS

Current

is

measured

through

the

use

of preClslOn

internal

shunts

resulting

in

accurate

indication

throughout

the

varIOUS rang

es.

SECTION

II

OPERATION

CAUTION

When making

measurements,

turn

off

the

power

to

the

circuit

under

test,

clip

the

test

leads

to

the

desired

points

and

then

turn on

the

power

to

take

the

reading.

T

urn

off

the

power

before

you

disconnec

t

the

meter.

ZERO

ADJUSTMENT

Before

takin

g

readings,

be

sure

that

the

pointer

is

on

zero.

If

pointer

is

off

zero,

adjust

by mli!ans of

the

slotted

screw

located

in

the

bakelite

case

directly

below

the

meter

scale

as

shown

in

Figure

1.

Use

a

small

screw-driver

to

turn

this

adjustment

slowly

to

the

right

or

left

until

the

pointer

is

directly

over

the

zero

point

on

the

scale.

STEP-BY-STEP

OPERATING

INSTRUCTIONS

D.

C.

VOLTAGE

MEASUREMENTS

0-1000

VOLTS

1.

Place

the

"OUTPUT-A.C.-D.C."

switch

in

the

"D.C."

pOSitlon.

2.

Rotate

the

range

selector

switch

to

anyone

of

the

vol-

tage

positions

required.

When

in

doubt

of

the

voltage

pre-

sent

,

always

use

the

highest

range

as

a

protection

to

the

OPERATION

meter.

After

obtaining

the

first

reading,

the

switch

can

be

reset

to

a

lower

range,

if

needed,

to

obtain

a more

accurate

reading.

3.

Plug

the

black

test

lead

into

the

jack

marked "COMMON

-"

and

the

red

te

st

lead

into

the

j

ac

k marked " +

".

Clip

the

other

end

of

the

black

lead

to

the

neg

ative

side

of

the

circuit

to

be

checked

and

the

other

end

of

the

red

lead

to

the

positive

side.

4.

Turn

on

the

power

to

the

circuit

to

be

tested.

If

the

pointer

deflects

to

the

left

of

zero,

the

connections

are

incorrect.

Turn

off

the

power

and

reverse

the

positions

of

the

test

clips.

5.

Read

the

voltage

on

the

black

arc

marked

"D.C."

which

is

second

from

the

top.

For

the

2.5

volt

ran

g

e,

use

the

0-250

figures

and

divide

by 100.

For

the

10, 50,

and

250

volt

ranges,

read

the

figures di-

reedy.

For

the

1000

volt

range

,

use

the

0-10 figures and

multiply

by 100.

D.

C.

VOLTAGE

MEASUREMENTS

1

000-5000

VOLTS

CAUTION

Use

extreme

care

when

you

check

high

voltage.

Always

turn

off

power

before

making

connections

and

do

not

touch

meter

or

test

leads

while

taking

the

reading.

1.

Place

the

"OUTPUT-A.C.-D.C."

swiech

in

the

"D.C."

position.

12

13

OPERATION

2.

Set

the

range

selector

swicch

in

the

1000

volt

posHlOn.

3.

Plug

the

black

test

lead

into

the

jack

marked

"COMMON

-"

and

che

red

cest

lead

into

the

jack

marked

"D.C.

5000

V."

4.

Be

sure

power

is

curned off

co

che

circuic

co

be

cesced

and

che

condensers

are

discharged;

then

clip

che

black

cesc

lead

co che

negacive

side

and

che

red

cesc

lead

to

che

positive

side.

S.

Turn

on

che

power.

6.

Read

che

voltage

using

che 0-50 figures

on

the

black

arc

marked

"D.C."

which

is

second

from

the

top.

Then

multiply

che

reading

by

100.

Turn

off

power

before

discon-

neccing

meter.

A.

C.

VOLTAGE

MEASUREME

NTS

0-1

000

VOLTS

1.

Place

the

"OUTPUT-A.C.-D.C."

switch

in

the

"A.C."

posHlon.

2.

Rocate

the

range

selector

switch

to

any

of

the

five

ran-

ges

required.

When

in

doubt

of

the

voltage

present,

always

use

the

highest

range

as

a

proteccion

to

the

meter.

After

obtaining

che first

reading,

the

switch

can

be

set

to

a

lower

range

for a more

accurate

reading.

3.

Plug

che

black

cesc

lead

into

che

jack

marked

"COMMON

. .

-"

and

che

red

cest

lead

inco che

jack

marked

..

+".

Clip

che

ocher

ends

of

che cesc

leads

co

the

cwo

sides

of

the

circuic

to

be

tested.

A.C.

volcage

will

read

correctly

re-

gardless

of

which

way

the

test

leads

are

connecced.

4.

Turn

on

che

power

to

the

circuit

co

be

cested.

14

-

OPERATION

S.

For

the

2.5

volt

range,

read

che

voltage

on

che

red

arc

marked

"2.5

V.A.C.

ONLY"

which

is

second

from

the

bottom.

For

che

other

ranges

use

the

red

arc

marked

"A.C."

which

is

third

from

the

borrom.

For

che 10,

SO

and

250

volt

ranges,

read

the

figures

di-

reccly.

For

che 1000 vole

range

read

the

0-10

figures

and

multiply

by 100.

A.

C.

VOLTAGE

MEASUREMENTS

1000·5000

VOLTS

CAUTION

High

voltage

is

dangerous.

Always

turn ott

power

before

you

connect

or

disconnect

test

leads.

Do

not

handle

mecer or

test

leads

while

power

is

on.

1.

Set

the

"OUTPUT-A.C.-D.C."

switch

in

the

"A.C."

posHlon.

2.

Rotate

the

range

selector

switch

to

the

1000 V. pOSHlOn.

3.

Plug

the

black

test

lead

into

the

jack

marked

"COMMON

-"

and

che red Cest

lead

into

the

jack

marked

"A.C.

5000

V "

4.

Be

sure

power

is

turned

off

in

circuic

to

be

tested,

and

then

clip

the

cesC

leads

co

che cwo

sides

of

the

circuit.

A.

C.

voltage

will

read

correctly

regardless

of

which

way

the

leads

are

connecced.

S.

Turn

on

the

power.

15

OPERATION

OPERATION

6.

Read

the

"oHa6e

on

the

red

arc

marked

"A.

c."

which

is

third

from

the

botCom.

Use

the

0-50 figures and

multiply

by 100.

Turn

off power

before

disconnecting

meter.

A.

F.

OUTPUT

MEASUREMENTS

1.

Place

the

"OUTPUT-A.

C.-D.

C. "

switch

in

the

"OUT-

PUT"

position.

When

the

switch

is

in

this

position,

an

internal

condenser

is

connected

in

series

for

the

purpose

of

blocking

out

the

D.C.

component

whenever

connections

are

made

directly

to

the

plate

of a

tube.

2.

Rotate

the

range

selector

switch

to

any

of

the

five

ranges

required.

When in doubt of

the

voltage

present,

always

use

the

highest

range

as

a

protection

to

the

meter.

After

obtain-

ing

the

first

reading,

the

switch

can

be

set

to a

lower

range

for a more

accurate

reading.

3.

Plug

the

black

test

lead

into

the

jack

marked "COMMON

-"

and

the

red

test

lead

into

the

jack

marked

It

+".

Clip

the

other

ends

of

the

test

leads

to

the

output

of

the

circuit

under

test.

4.

Turn

on

the

power.

5.

For

the

2.5

volt

range

use

the

red

arc

marked

"2.5

V.A.C.

only"

which

is

second

from

the

bottom.

OTHER

RANGES

...

For

the

10, 50,

and

250

volt

ranges,

read

the

figures

direct-

ly.

For

the

1000 volt

range,

use

the

0-10 figures

and

multi-

ply by 100.

For

the

other

ranges,

use

the

red

arc

marked

"A.C."

which

is

third

from

the

bottom.

REACTANCE

OF

SERIES

CONDENSER

The

reactance

of

the

series

condenser

used

when

reading

output

volts

causes

a

slight

error

which

varies

with fre-

quency.

This

is

explained

in

Section

III.

VOLUME

LEVEL

MEASUREMENTS

1.

Set

the

"OUTPUT-A.

C.-D.c."

switch

in

the

"A.

c."

position.

2.

Rotate

the

range

selector

switch

to

any of

the

five

ranges

required.

3.

PI

ug

the

test

leads

into

the

two

jac

ks

marked

"+"

and

"COMMON

-"

and

connect

the

clips

to

the

two

sides

of

the

circuit

to

be

checked.

4.

Turn

on

the

power and

read

decibels

on

the

black

arc

marked

"D.B."

which

is

at

the bottom of the

scale.

In

order

to

obtain

decibel

readings

it

is

necessary

to add

algebraically

the

scale

reading

and

the

number

shown

at

the

setting

of

the

range

selector

switch.

For

example,

if

the

scale

indication

is

-4

D.

B. with

the

switch

in the +

12

D.

B.

position,

the

true

reading

will

be +8

D.

B.

because

(-4)

+

(+

12)

= +8.

(For

.001

watt

-600 ohm

reference

level

add +7

D.B.)

D.

C.

RESISTANCE

MEASUREMENTS

CAUTION

Before

making

any

resistance

measurements

in a

radio

circuit,

be

sure

the

current

is

turned

off

so

that

no

voltage

exists.

Otherwise

the

meter

may be dam-

aged.

16

17

OPERATION

1.

Place

the

"OUTPUT-A.C.-D.C."

switch

in

the

"D.C."

posJtJOn.

2.

Rotate

the

range

selector

switch

to

any

of

the

three

ranges

required.

R X 1 for

0-2000

ohms.

R X 100 for 0 - 200,000

ohms.

R X 10,000 for

0-

20 megohms.

3.

Plug

the

test

leads

into

the

two

jacks

marked

"+"

and

"COMMON

-".

Short

the

ends

of

(he

leads

and

set

the

pointer

to

zero

by

rotating

the

"ZERO

OHMS" knob.

4.

Separate

the

ends

of

the

test

leads

and

clip

them

across

the

portion

of

the

circuit

to

be

measured.

5.

Read

ohms

on

the

black

arc

at

(he

top of

the

scale.

For

range

R X 1,

read

the

figures

directly.

For

range

R X 100,

multiply

the

reading

indicated

by

100,

or

add

two

zeros.

For

range

R X 10,000,

multiply

the

reading

indicated

by

10,000,

or

add

four

zeros.

Example:

A 2 megohm

resistor

should

be

checked

on

the

R X 10,000

range.

The

reading

on

the

scale

will

be 200.

Adding

four

zeros

will

give

2~000,000

ohms,

or 2

megohms.

CAUTION

Do

not

leave

the

range

selector

switch

in

a reSlS-

tance

measurement

position

when

the

meter

is

not

in

use

because

the

test

leads

may

become

shorted

and

run down

the

internal

battery.

It

is

also

possible

OPERATION

that

the

instrument

may

be

connected

across

a

volt-

age

accidentally

and

thus

cause

damage

to

the

meter.

CURRENT

MEASUREMENTS

IN

D.

C.

CIRCUITS

1.

Place

the

"OUTPUT-A.C.-D.C."

switch

in

the

"D.C."

posJtlon.

2.

Rotate

the

range

selector

switch

to

any of

the

ranges

required.

When

in

doubt

of

the

current

present,

always

use

the

highest

range

as

a

protection

to

the

meter.

After

obtain-

ing

the

first

reading,

the

switch

can

be

reset

to a

lower

range

if

needed.

3.

Plug

the

black

test

lead

into

the

jack

marked "COMMON

-"

and

the

red

test

lead

into

the

jack

marked

"+".

For

the

10

ampere

range

use

the

jacks

marked

"-10

A."

and

"+

10

A."

4.

Break

the

circuit

to be

tested

and

insert

the

meter

in

series

by

connecting

the

red

test

lead

to

the

positive

side

and

the

black

test

lead

to the

other

side.

5.

Turn

on

the

power.

6.

Read

milliamperes

on

the

black

arc

which

is

second

from

the

top.

If

the

pointer

is

forced

against

the

stop

at

the

lefe

of

the

scale,

the

connections

are

incorrect.

Turn

off

the

power

and

reverse

the

positions

of

the

test

clips.

For

100

microamperes,

read

the

figures 0-10 and

multiply

by 10.

For

10

milliamperes,

read

the

figures

directly.

For

100

milliamperes,

read

the

figures 0-10

and

multiply

by 10.

18

19