RCA WO-33A User Manual

PRICE

ONE

DOLLAR

CATHODE-RAY

OSCILLOSCOPE

Type

WO-33A

• Specifications

•

Operation

• Applications

•

Maintenance

e)

RADIO

CORPORATION

0'

AMERICA

~

.'

~l:

ELECTRON

TUBE

OlVISION

HARRISON,

N.J.

~

ELECTRONIC

INSTRUMENTS

CAMDEN,

N.

J.

Safety

Precautions

The

metal

case of this instrument

is

connected

to

the

ground

of

the

internal circuit.

For

proper

opera-

tion,

the

ground

terminal of

the

instrument should

. always

be

connected

to

the

ground of

the

equipment

under

test.

The

WG-349A

Direct/Low-Capacitance

Probe

and

Cable

has a shield throughout its entire

length

which

is

connected

to

the

instrument

ground

and

case.

Care

should

be

exercised to avoid striking

the

cathode-ray

tube

or subjecting it to more

than

mod-

erate

pressure

in

handling.

Because

the

tube

contains

a high

vacuum,

implosion might result in injury

from flying glass.

An

important

point

to

remember

is

that

there is

always

danger

inherent

in testing electrical

equip-

ment

which

operates

at

hazardous voltages. There-

fore,

the

operator

should

thoroughly familiarize him-

self with

the

equipment

under

test before working

on it,

bearing

in

mind

that

high voltages

may

appear

at

unexpected

points in defective

equipme~t.

Addi-

tional

precautions

which

experience in

the

industry

has

shown

to

be

important

are listed below.

1.

It

is good

practice

to

remove power before

connecting

test

leads

to

high-voltage points.

If

this

is impractical,

be

especially careful to avoid acci-

dental

contact with

equipment

racks

and

other

ob-

jects which

can

provide a ground.

Working

with

one

hand

in your pocket

and

standing

on

a properly

insulated

Hoor

lessens the

danger

of shock.

2. Filter capacitors may store a

charge

large

enough

to

be

hazardous. Therefore,

discharge

filter

capacitors before

attaching

test

leads.

3.

Remember

that

leads with

broken

insulation

provide

the

additional

hazard

of high voltages

ap-

pearing

at

exposed points along

the

leads.

Check

test leads for frayed or broken insulation before

working

with

them.

4. To lessen

the

danger

of accidental shock,

disconnect test leads immediately

after

test

is

completed.

.5.

Remember

that

the

risk of severe shock

is

only

one of

the

possible hazards.

Even

a minor shock

can

place

the

operator

in '-hazard of

more

serious

risks such as a

bad

fall or

contact

with

a source

of

higher

voltage.

B.

The

experienced

operator

continuously

guards

against injury

and

does

not

work on

hazardous

cir-

cuits unless

another

person is available

to

assist

in

case of accident.

ITEMS

Supplied

with

WO-33A

Direct/Low-Capacitance

Probe

and

Cable

Type

No. WG-349A

1

BX4

1

BBK7A

1 BC4

2

12AT7

1 BBR8

Instruction Booklet

Available

on

Separate

Order

1 RCA

3AQPl

For

rf

applications from

500

Kc to 250 Mc:

Demodulator

Probe ........

Type

No. WG-350A

Devices

or

arrangements

shown

or

described

herein

may

use

patents

of

RCA

or

othet's.

Information

contained

herein

is

furnished

without

responsibility

by

RCA

for

its

use

and

without

prejudice

to

RCA's

patent

rights.

TMK

®.

Marco

Registrodo

• 2 •

WQ-3]AIB(2)

3-60

Printed

in

U.S.A.

Cathode-Ray Oscilloscope

Type

WO-33A

Contents

Safety

Precautions

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

Items

Supplied

with

WO-33A
Description
Specifications
Functions

of

Controls

and

Terminals.

Operation

Initial

Procedure

Vertical-Amplifier

Operation

Horizontal-Amplifier

Operation

Sweep-Oscillator

Operation

Use

of

WG-349A

Probe

Calibration

and

Voltage

Measurement

Applications.

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

Analyzing Composite Television Waveforms
Alignment

Schematic

Diagram

of

WO-33A

...... .

General

Applications

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

Square-Wave

Testing of Audio Amplifiers

..
Phase-Shift Measurements
Frequency

Measurements ............................ .......

..

Industrial

Applications

........................... ,

..

Engine-Pressure Analysis
Vibration Measurements

.

Maintenance.

General
Astigmatism Adjustment
Vertical Attenuator Alignment

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

Internal Calibrator Control

Adjustment...

Repair

Service

Replacement

Parts

List.

Warranty

• 3 •

Page

:\'/0,

2

2

5

6

8
8
8
8
8

9

9

..11

..........

11

14

12-13

18
18
18

19
20
20
20

21

..... 21

21
21

21

...

21

22-2.3

23

Description

The

RCA

WO-33A

is a 3-inch oscilloscope de-

signed for

"on-location"

and

service-shop use in

servicing color

and

black-and-white television re-

ceivers, Hi-Fi

equipment,

PA

and

sound reenforcing

systems,broadcast

station

and

remote equipment,

communications

and

industrial electronic equipment.

A novel feature of

the

WO-33A is

the

Vertical

Input

Attenuator

which

automatically switches

the

amplifier from

Wide

Band

to Narrow Band

when

in

the

three

highest

gain positions.

Another

important

feature of

the

WO-33A

is

the

exceptionally

high

gain in its vertical amplifier.

There

is enough sensitivity

to

provide a useful dis­play of signals from low-level microphones, phono­pickups

and

other

weak

signals found in radio/TV

receivers, audio amplifiers, etc.

A voltage-calibrated, frequency-compensated ver-

tical-input attenuator,

an

internal calibrating-voltage

source,

and a graph

screen scaled directly in volts

make

it

possible

to

use

the

WO-33A as a visual

voltmeter.

The

unique

system of calibrating the

graph

screen provides for scaling voltages directly

from

the

screen.

The

measurement

procedure

is

very

similar

to

that

employed

with

a vacuum-tube volt-

meter. A calibrating voltage

is

automatically applied

to

the vertical amplifier

when

the

bandwidth

control

is

set

to

the

calibration position. This switch also dis-

connects internally

the

input

and

attenuator

circuits,

making

it

unnecessary

to

remove leads

and

probes

from

the

external circuit

under

test. These unique

facilities make voltage calibration

and

measurement

a simple, almost

automatic

procedure.

The

sweep-frequency control

is

continuously

adjustable from 15 cps

to

75

Kc.

The

sweep oscil-

lator has excellent stability

at

high sweep rates, a

fast retrace,

and

adequate

linearity throughout its

frequency range.

The

over-all frequency range of

the

oscillator

is

divided

into four basic ranges; a

vernier adjustment,

which

overlaps

the

basic sweep

ranges, provides exact

adjustment

of

the

sweep fre-

quency.

The

amount

of sync signal

fed

to

the

sweep

oscillator may

be

adjusted

by

means of a front-panel

• 4 •

control. Sweep synchronization is exceptionally
stable throughout

the

sweep range

of

the oscillator.

A

phase

control is provided for varying

the

phase

of the internal sweep voltage

when

the

"LINE"

position of

the

H/SWEEP

SEL

cOlltrol

is

used, en-

abling

the

WO-33A to

be

phased

with

an

external

line-frequency sweep oscillator.

To

facilitate its use,

the

WO-33A is

equipped

with

a specially designed single-unit

probe

and

input

cable. This accessory,

the

WG-349A

DirectiLow-

Capacitance Probe

and

Cable, is provided

with a blue

input

lead

and

a yellow input lead.

When

the

blue

input

is used,

the

test signal

is

fed directly

to

the

vertical-input terminal.

When

the

yellow

input

is

used, a special high-impedance circuit

in

the

probe

is

connected in series with

the

test point

and

the

'scope. This high-impedance circuit presents

an

over-

all

input

resistance of 10 megohms

and

an

input

capacitance of approximately 10

ppf

to

the

test

cir-

cuit. This feature reduces circuit-loading effects

and

permits use

in

circuits which would not function

properly

if

loaded

down

by a conventional oscillo-

scope.

The

WO-33A

can

be

used to trouble-shoot

and

signal

trace

all sections of

both

black-and-white

and

color-TV receivers. The voltage-calibrating facil-

ities,

wide

band-pass,

and

high-impedance

input

characteristics make possible observations

and

meas-

urements of color-burst signals

and

othe'; critical,

,.

high-frequency waveshapes in circuits

which

are

sensitive to loading effects.

The

size

and

weight

of the WO-33A make

it

an

especially portable instrument, useful

in

such

appli-

cations as industrial maintenance

and

trouble-shoot-

ing, general waveform analysis, adjustment of

radio

receivers

and

transmitters, square-wave

and

general
testing of audio equipment, peak-to-peak voltage
measurements,

and

observation of

vacuum-tube

characteristics.

The

WO-33A is a versatile

and

re-

liable instrument, well suited to applications

which

require a

dependable

oscilloscope.

Specifications

NOTE:

Performance

figures

are

for

a line

voltage

of 117

volts,

60

cps.

Frequency

Response:

Electrical

Vertical Amplifier:

Wide-Band Positions (5.5 cps to 5.5

Mc)

..................................................... flat within - 3

db

High-Sensitivity Positions:

20

cps

to

150

Kc

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

3 cps to 1.5 Mc .................................................... .

Horizontal Amplifier (3.5 cps to 350 Kc)

Deflection

Sensitivity:

Vertical Amplifier:

At

V

INPUT

connector .......................................

With

WG-349A Blue

Lead

With WG-349A

Yellow

Lead

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

(Wide-Band)

Positions

rms

p-p

0.10

0.3

0.10

0.3

1.0

3.0

. ..... flat within - 3

db

flat within - 6 db

.... flat within - 6 db

(High-Sensitivity)

Positions

rms

p-p

.003

0.01

volt/in

.003

0.01

volt/in

.03

0.1

volt/in

Horizontal Amplifier

(at H INPUT

terminal)

Rise

Time

(Vertical Amplifier):

.......................................................................................... 0.9

rn1S

volt/in

5.5-Me

Positions

0.1 psec

Input

Resistance

and

Capacitance:

Vertical Amplifier:

At V INPUT

connector ......................... ................. ............... ...................... 1 megohm shunted by approx. 50

f.Lpf

With

WG-349A Blue Lead ...................... ....... ........ ........ ......

...

...

...... 1 megohm shunted by apf)fox. 90

f.Lf.L

f

\Vith \VG-349A Yellow

Lead

.................... . ................................. 10 megohms shunted by

ap~rox.

10

pf.Lf

Horizontal Amplifier

(at H INPUT

terminal) .................................................... . .....

io

megohms

EXT

SYNC

Input

Terminal........................ . .................................................................... 250 K to 55 K

Sweep

Oscillator:

Frequency Range (continuously adjustable)

Sync ................................... .

Sync

Range.

Maximum

AC

Input

Voltage

(at

Lo-Cap

Probe):

(In

presence of 400 volts

dc)

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

Phase-Control

Range

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

Power

Requirements:

Voltage ....

Average

Power Consumption .................................... .

1-6BR8
1-6BK7A

Tube

Complement

2-12AT7

Height
Width

1-6X4

Mechanical

8

31f1

14

6

1111

12

• 5 •

Length
Weight

15 cps to 75

Kc

........................ External; ± Internal

...

To

4.5 Mc

.....

600 p-p volts

o to 160 degrees

105-125 volts, 50-60 cps

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

50 watts

1-6C4
1-3AQPl

.......

lOW'

14 lbs

Functions

of

Controls and Terminals

o 0 0 0

E;)a=JE;)

00

00

OFF-INTENSITY - Applies

power

to

the

instrument

and

in-

creases intensity of

the

trace

on

the

screen of

the

cathode-ray

tube

when

control

is

turned

clockwise

from

"OFF"

position.

FOCUS - Adjusts

the

sharpness

of

the

trace. Normally requires

adjustment

when

setting

of

the

INTENSITY

control is

changed.

000

0

o 0 0 0

v

POS

- Adjusts vertical posi-

tion of trace.

H

POS

- Adjusts horizontal po-

sition of trace.

o

000

• 6 •

V-CAL - Adjusts sensitivity, or

calibrates vertical amplifier to cor­respond with positions on V
RANGE switch.

°n°

O~O

000

0

E;)c=~

00

00

00

00

V RANGE -

In

"CAL"

position,
disconnects vertical amplifier from
input

connector,

and

supplies a

calibrating voltage which should

be

adjusted

with "V-CAL" control

to
full-screen deflection. Adjusts over­all sensitivity of vertical amplifier
in

"3-to-l"

steps. Automatically

changes

bandwidth

of vertical amplifier when going

from ".2" to ".6" positions.

V INPUT -

Feeds

the

input sig-

nal to

the

vertical amplifier through

the

attenuator

circuits.

:0:

000

°

&c=

~

'lac

00

SYNC - Selects the source of

the

synchronizing signal.

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RCA

WO-33A Cathode-Ray Oscilloscope iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii

:0:

o~/=o~o

~c

00

GND - Connected directly to case

and

chassis.

H/SWEEP

SEL

- Selects

the

frequency

range

of

the

sweep

os-

cillator.

Used

in conjunction with

the

SWEEP

VERNIER

control.

Also switches

the

Horizontal Amp-

Mer

to

"H

INPUT"

or to a sine­wave sweep voltage of power-line
frequency.

0(jJ}0

o 0

000

00

00

SYNC/PHASE - Controls

the

amplitude

of

the

synchronizing

voltage applied to

the

grid of

the

sweep oscillator; should

be

adjusted

to minimum setting necessary to

lock

pattern

in a stationary position.

Works zero-center for internal

sync. Adjusts external sync by reg-

ular clockwise rotation. Also controls phase of

the

sinusoidal

sweep

voltage

when

the

H/SWEEP

SEL

switch is in

the

"LINE"

position.

• 7 •

:0:

EXT

SYNC/H

INPUT

- An

external synchronizing signal for
the

sweep

oscillator should

be

con-

nected

between

this terminal

and

the

ground

terminal.

The

"SYNC"

switch should

be

set to "EXT". An
external signal for the horizontal
amplifier should also be connected

between this terminal

and

the

ground terminal

and

the

H/SWEEP

SEL

control set to

"H

IN". A positive-

going signal will cause

the

spot to deflect to

the

right; a negative-going signal will cause

the

spot to

deflect to

the

left.

SWEEP

VERNIER - Provides

continuous control of

the

oscillator

sweep frequency over

the

range

selected by

the

SWEEP

controL

Also provides overlap

of

the

SWEEP

control positions.

0QO

o 0

000

0Q

o 0

000

H GAIN - Adjusts

the

gain of

the

horizontal amplifier

and

varies

the

width

of

the

horizontal trace.

Does not provide

enough

control

to

reduce

trace length to zero.