Hameg HM604 Service manual

Table of contents

Technical Data

Accessories .....................

Operating Instructions

General Information
Use of tilt handle
Safety.
Operating conditions
Warranty
Maintenance
Mains/Line voltage change
Type of Signal
Amplitude Measurements
Time Measurements
Connection of Test Signal
Operating
First Time Operation
Trace Rotation TR
DC Balance Adjustment
Use and Compensation of Probes
Operating Modes of the Y Amplifier
X-Y Operation
X-Y Phase Measurements

Dual Trace Phase Difference Measurements
Measurement of an amplitude modulation
Triggering and
Triggering of video signals

Function of variable HOLD OFF control
Sweep Delay /After Delay Triggeringe

Delay Mode Indication
Component Tester

Miscellaneous
Test Patterns

Short Instruction

Front Panel Elements

Folder with Front View

Test Instructions

General

Cathode-Ray Tube: Brightness, Focus,

Astigmatismus Check

Symmetry and Drift of

Calibration of the Vertical Amplifier
Transmission Performance of the Vertical Amplifier

............................T2

Operating Modes: CH I/II-TRIG.

Triggering Checks

Timebase

SweepDelay

Component Tester

Trace Alignment

Miscellaneous

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

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

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

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

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

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

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

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

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

Timebase

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

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

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

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

Linearity, Raster Distortions . T 1

CHOP., INV. l/II and XY-Betrieb . T 2

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

thevertical

........

.......

......

......

Amplifier

.........

l/II,

DUAL, ADD,

....

. .

....

M 10

P

1

Z 1

M 1
M 1
M 1
M 2
M 2
M 2
M 2
M 3
M 3
M 4
M 5
M 6
M 7
M 7
M 7
M 8
M 9
Ml 0
Ml 0

Ml 1
Ml 1
Ml 2
Ml3
Ml 3
Ml 5
Ml 5
Ml 7
Ml 8

K 1.

K

2

T 1

T 1
T 1
T 1

T 3

T 3
T 4
T 4
T 4
T 4

Oscilloscope

HM 604

Service Instructions

General .......................S 1

Instrument Case Removal ............. S 1

Operating Voltages ................. S 1

Minimum Brightness ................ S 1

Astigmatismus control ............... S 1

Trouble Shooting the Instrument ..........S 2

Replacement of Components and Parts ......S 2

Replacement of the Power Transformer ......S 2

Adjustments ....................S 3

Circuit Diagrams

Block Diagram

Wiring Diagram

Identification of Components
Y Input, Attenuator, Preamplifier CH.
Y intermediate Amplifiers, Trigger Pre-Amplifiers,

Component Tester

Y Final Amplifier

Post Trigger, Field Selector

Timebase (analog)
Timebase
Tim,ebase Generator

X Final Amplifier, Calibrator

CRT and HV circuit

Power Supply

Component Locations

XY Board

TB Board

PTFS Board

TBG, CAL, YF Boards

CO, EY, Z Boards

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

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

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

(digital)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

l/II

......

D 1
D 2
D 3
D 4

D 5
D 6
D 7
D 8
D 9

DlO

Dl

D12
D13

D14
D15
D16
D17
D18

1

Subject to change without notice

9.88. 604

Specification

Vertical

Operating modes: Channel I or Ch. II separate,
Channel I and II: alternate or chopped.
(Chopper frequency approx.
Sum or difference of Ch. I and Ch. II,
(with invert buttons for both Channels).

XY-Mode: via Channel I and Channel II.
Frequency range: 2x DC to 6OMHz (- 3dB).

Risetime: approx. 5.8ns. Overshoot: II %.
Deflection coefficients: 12 calibrated steps
from 5 mV/div. to
variable 2.5: 1 to min.
Accuracy in calibrated position:
Y-Magnification x5 (calibrated) to 1 mV/div.
(Frequency range DC to
input impedance: 1 MQ II
Input coupling: DC-AC-GD (Ground)
Input voltage: max. 400V (DC + peak AC).

Y-output from CH I or CH II, = 50
Delay Line: approx. 90ns.

Mhtion

ZOV/div

50V/cm.

0.5MHz).

in l-Z-5 sequence,

+3%.

20MHz. -

3OpF.

3dB.

mV,Jdiv.

(50

Trigger System

With automatic
normal with level control from DC- 100 MHz.
LED indication for trigger action.
Slope: positive or negative.

Sources: Ch. I, Ch. II, line, external.
Coupling: AC (21

Threshold: external
Active TV-Sync-Separator for line and frame.

Slope positive or negative.

2nd. Triggering

trolled (independent from slope direction).

+ selection for TV mode.

Threshold: 1 div; typlcal
Trigger bandwidth:

lOHz-IOOMHz (P5mm

OHz

LF

HF(?50kHzmlOOMHz).

to approx. 20 MHz), DC

(DC -

550 kHz),

r50mV.

(Del. Trig.):

0.5div.

225

Hz to 60 MHz.

autom. or slope con-

height)

52)

60 MHz Universal Oscilloscope

2 Channels, 1
Timebase: 2.5s/div. to 5ns/div. including
Triggering:

mV/div.

DC-lOOMHz,

Sensitivity, Delay Line, Component Tester

x10

Magnifier&Sweep Delay

TV Sync Separator, After-Delay Trigger

Time coefficients: 23 calibrated steps

from

50ns/div.

variable 2.5: 1 to min.

accuracy in calibrated position:
with X-Magnifier

Hold-Off time: variable (2 5 : 1).

Delay: 7 decade steps

from 1 OOns

Bandwidth X-Amplifier:

Input X-Amplifier via Channel

sensitivity see Ch. II specification.

X-Y phase shift:

Ramp output: approx 5V. positive going

Test voltage: max.

Test current: max.

Test frequency: 50 - 60 Hz (line frequency).

Cathode-ray tube:

rectangular screen, internal graticule 8x10 cm.

Total acceleration voltage: 12

Trace rotation: adjustable on front panel.

Calibrator: square-wave generator switchable

from

Output voltage: 0.2V and 2V fl

Protective system Safety Class I

Linevoltage: 110. 125, 220,

Line frequency: 50 to 60Hz.

Power consumption: = 40 Watt.

Weight: approx. 8kg. Colour: techno-brown.

Cabinet: W 285, H 145, D 380mm.

Lockable tilt handle.

to 1

s/div

in l-2-5 sequence,

2.5s/div,

x10 (k

to 0.1 s, variable approx 10 : 1 to 1 s.

<3”

below 120

8.5V,,,

8mA,,,

150CTB31

=

1

kHz

to 1 MHz

+3%.

5%) to =

DC-5MHz (-3dB).

II,

(open circuit).
(shorted).

P43l123,

(t,

approx. 3ns).

24OV- *IO%.

5nsIdiv..

kHz.

kV.

%.

(IEC

348).

With its variety of operating and trigger modes, the HM604 is a new in-

novative general purpose oscilloscope satisfying a wide range of exacting re-

quirements in laboratory, production, and service. The dual-channel measure-

ment amplifier ensures highly faithful waveform transfer characteristics,
which can be readily checked on the built-in fast-risetime 1 MHz Calibrator
from probe tip to CRT screen! Using Y-axis magnification, the instrument’s

high sensitivity enables stable displays of very small signals as low as 0.5

mV.

An analog output is provided for connecting multimeters or counters. Another

important feature is the internal delay line for observations of the leading edge

of a signal. As in dual-time base oscilloscopes, the HM604 features a calibra­ted sweep delay mode, allowing smallest waveform sections to be expanded

up to 1000 times.

The

HM604’s

most outstanding feature, however, is the unique, newly
developed automatic After-Delay Trigger mode to ensure extremely stable
displays and jitter-free measurements of asynchronous signal sections and
bursts or pulse trains, independent of amplitude fluctuations. An active

TV-

Sync-Separator further enhances trigger quality of video frame and line sig­nals. In the alternate trigger mode, two signals of different frequencies can be
compared.

With this state-of-the-art oscilloscope, HAMEG again sets a new price/

performance standard which is not likely to be met by others in this category.

Users will be particularly impressed by the instrument’s outstanding versatility
and ease of operation. These features are possible in the HM604 due to

HAMEG’s

meticulous attention to detail and many decades of successful

design experience.

-

Subject to change

without

notice

Test

Cable Banana - BNC

Coaxial test cable; length 1.15 m, characteristic impedance 5Ofi.
Cable capacitance

12OpF.

Input voltage max.

5OOV,.

HZ32

Modular Probes

The clear advantage over ordinary probes are field replaceable
parts and the HF-compensation feature on the 10: 1 attenuator pro-

bes For the first time, probes in this price range allow adjustments
of their HF-characteristics to match individually the input imped­ance of each scope. This is particularly important for scopes with

higher bandwidths (>SOMHz), as otherwise strong overshoot or

rounding may occur, when measuring fast-rising square waves.
An exact HF-compensation, however, is only possible with square-
wave generators having a

already feature such a calibration generator. For other oscillo-

scopes, it is available as accessory item
following Modular Probes are available (HZ36 without HF-com-

pensation):

risetime <5ns.

Most

HZ60-2.

HAMEG

scopes

At present the

Test Cable BNC-BNC

Coaxial test cable; length 1 m, characteristic impedance
Cable capacitance 126pF. Input voltage max.

5OOV,.

Adapter Banana - BNC

Two 4mm binding posts
male plug. input voltage max.

5Ofz

Through-Termination

For terminating systems with

Maximum load 2 W. Max. voltage 1

(19mm

between

5OOV,.

5OS2

centers)

characteristic impedance.

OV,,,.

HZ34

500.

HZ20

to standard BNC

HZ22

Carrying Cases

For HM 103
For HM203, HM204. HM205, HM208, HM408. HM604,

HM605 and HM 1005

Viewing Hood

For HM203, HM204, HM205, HM208, HM408, HM604, HM605

and HM 1005

Scope-T-tar

HZ95

HZ96

HZ47

HZtiOa

Type

Attenuation Ratio

Bandwidth min. (MHz)

Risetime

(ns)

Inp. Capacitance

Inp. Resistance (MR)
Inp. Voltage max.
Cable Length (m)

Spare Cable for HZ36
Spare Cable for HZ51, HZ54
Sparepart Kit (2 sprung

Special probe for AM-demodulation and wobbulator measure-

ments. HF-Bandwidth

age 250mV -

peak AC. Cable length 1.2m.

High

For measurement of voltages up to
approx. 500 mQ. Recommended load resistance1
(switchable). Attenuation ratio 1000 : 1. Bandwidth 1 MHz. Cable

length 1.5 m. BNC connector.

5OV,,,.

Vdtaget

HZ36

selectable

l:l/lO:l 1O:l

IO/

3513.5

(pF)

47/18

(V,)

hooks, 2 screw tips, 1 ground cable)

I’mbe

HZ51 HZ52 HZ53

IO:1

100

150

<2

16

l/10

600 600

1.5 1.2

IOOkHz

DC isolation Voltage 200V DC including

10

-5OOMHz

(HF) 1OO:l

250

tl.4

16
10 100

600 1200

1.5 1.5

(+ldB).

150

<2
65

AC

HZ54

selectable

1:1/10:1

IO/

150

35/<2

40/I

l/10

600

1.2

HZ39
HZ57
HZ46

InputVolt-

Hz58

15kV,,.

Input resistance

Ma/l

0

MQ

For Checking the Y amplifier, timebase, and compensation of all
probes, the
square-wave generator with switchable frequencies of DC, 1

IOOHz,

nals of 25

100x probes); accuracy +q %. Battery-powered.

8

I-IO-I

mV,,

HZ6O-2

is a crystal-controlled, fast rising (typ. 3ns)

OOkHz,

and 1 MHz. Three BNC outputs provide sig-

into 50 M,

0.25V,,

and

2.5V,,

(open circuit for 1 Ox and

Component-Tester

Indispensable for trouble-shooting in electronic circuits. Single
component and in-circuit tests are both possible. The HZ65 oper­ates with all scopes, which can be switched to X-Y operation (ext.
horizontal deflection). Non-destructive tests can be carried out on
almost all semiconductors, resistors, capacitors, and coils. Two
sockets provide for quick testing of the 3 junction areas in any small
power transistor. Other components are connected by using 2
banana jacks. Test leads supplied.

Examples of Test Displays:

ShortcircuIt

Capacitor

33~F

Junction E-C Z-Diode

-lO-

HZ65

t8V

Printed in West Germany 5/90

Zl

Operating Instructions

General Information

This oscilloscope is easy to operate. The logical arrange-

ment of the controls allows anyone to become familiar with
the operation of the instrument after a short time, however,
experienced users are also advised to read through these

instructions so that all functions are understood.

Immediately after unpacking, the instrument should be
checked for mechanical damage and loose parts in the in­terior. If there is transport damage, the supplier must be in­formed immediately. The instrument must then not be put

into operation.

Check that the instrument is set to the correct mains/line

voltage. If not, refer to instructions on page M2.

Use of tilt handle

To view the screen from the best angle, there are three dif-

ferent positions (C, D, E) for setting up the instrument. If the

instrument is set down on the floor after being carried, the
handle remains automatically in the upright carrying posi-

tion (A).

In order to place the instrument onto a horizontal surface,
the handle should be turned to the upper side of the oscillo­scope (C). For the D position

should be turned in the opposite direction out of the carry

ing position until it locks in place automatically underneath

the instrument. For the E position (20” inclination), the

handle should be pulled to release it from the D position and

swing backwards until it locks once more.
The handle may also be set to a position for horizontal carry-

ing by turning it to the upper side to lock in the B position. At

the same time, the instrument must be moved upwards,

because otherwise the handle will jump back.

B

6

(IO’

inclination), the handle

E

cict

20”

Safety

This instrument has been designed and tested in accor­dance with
Electronic Measuring Apparatus, and has left the factory
in a safe condition. The present instruction manual contains
important information and warnings which have to be fol­lowed by the user to ensure safe operation and to retain the
oscilloscope in safe condition. The case, chassis and all
measuring terminals are connected to the protective earth
contact of the appliance inlet. The instrument operates ac­cording to Safety C/ass I (three-conductor power cord with

protective earthing conductor and a plug with earthing con­tact). The mains/line plug shall only be inserted in a socket
outlet provided with a protective earth contact. The protec­tive action must not be negated by the use of an extension

cord without a protective conductor.

Warning! Any interruption of the protective conductor

inside or outside the instrument or disconnection of the
protective earth terminal is likely to make the instru-

ment dangerous. Intentional interruption of the protec-

tive earth connection is prohibited. The mains/line plug

should be inserted before connections are made to

measuring circuits.

The grounded accessible metal parts (case, sockets, jacks)

and the mains/line supply contacts (line, neutral) of the in-

strument have been tested against insulation breakdown

with 2000 Vr.m.s.

Under certain conditions, 50 Hz or 60Hz hum voltages can
occur in the measuring circuit due to the interconnection
with other mains/line powered equipment or instruments.
This can be avoided by using an isolation transformer

(Safety Class II) between the mains/line outlet and the

power plug of the instrument. When displaying waveforms
where the “low-level” side of the signal is at a high poten­tial, even with the use of a protective isolation transformer,

it should be noted that this potential is connected to the os-

cilloscope’s case and other accessible metal parts. High
voltages are dangerous. In this case, special safety precau-

tions are to be taken, which must be supervised

personnel if the voltage is higher than 42V.

Most cathode-ray tubes develop X-rays. However, the

dose equivalent rate falls far below the maximum per-

missible value of

Whenever it is likely that protection has been impaired, the

instrument shall be made inoperative and be secured

against any unintended operation. The protection is Ii kely to

be impaired if, for example, the instrument

-

shows visible damage,

-

fails to perform the intended measurements,

-

has been subjected to prolonged storage under un-

favourable conditions (e.g. in the open or in moist envi-

ronments),

-

has been subject to severe transport stress (e.g. in poor

packaging).

IECPublication346,SafetyRequirementsfor

(5OHz).

by qualified

36pA/kg (0.5mRlh).

Subject to change without notice

Ml

Operating conditions

Maintenance

The instrument has been designed for indoor use.
The permissible ambient temperature range during opera­tion is + 15°C

. . .

+3O”C. It may occasionally be subjected to

temperatures between + 10°C and - 10°C without degrad-

ing its safety. The permissible ambient temperature range
for storage or transportation is -40°C .

+70X.

The maximum operating altitude is up to 2200m (non-

operating 15000m). The maximum relative humidity is up
to 80%.

If condensed water exists in the instrument it should be

acclimatized

before switching on. In some cases (e.g.

extremely cold oscilloscope) two hours should be allowed

before the instrument is put into operation. The instrument
should be kept in a clean and dry room and must not be
operated in explosive, corrosive, dusty, or moist environ-

ments The oscilloscope can be operated in any position,

but the convection cooling must not be impaired. The

wen-

tilation holes may not be covered. For continuous opera­tion the instrument should be used in the horizontal posi­tion, preferably tilted upwards, resting on the tilt handle.

The specifications stating tolerances are only valid if
the instrument has warmed up for 30 minutes at an
ambient temperature between

+15C”

and +3OC9 Val­ues not stating tolerances are typical for an average
instrument.

Warranty

Each instrument runs through a quality test with 10 hour
burn-in before leaving the production. Practically every early
failure is detected in intermittent operation by this method.

However, it is possible that a component fails only after a

lengthy operating period. Therefore a functional guaran-

tee of 2 years is given for all units. The condition for this is
that no modifications have been made in the instrument. In
the case of shipments by post, rail or carrier it is recom-

mended that the original packing is carefully preserved.
Transport damages and damage due to gross negligence

are not covered by the guarantee.

In the case of a complaint, a label should be attached to the
housing of the instrument which describes briefly the faults
observed. If at the same time the name and telephone
number (dialing code and telephone or direct number or
department designation) is stated for possible queries, this

helps towards speeding up the processing of guarantee
claims.

Various important properties of the oscilloscope should be
carefully checked at certain intervals. Only in this way is it
largely certain that all signals are displayed with the accu­racy on which the technical data are based. The test
methods described in the test plan of this manual can be
performed without great expenditure on measuring instru­ments. However, purchase of the new HAMEG scope test­er HZ 60, which despite its low price is highly suitable for
tasks of this type, is very much recommended.

The exterior of the oscilloscope should be cleaned regularly
with a dusting brush. Dirt which is difficult to remove on the
casing and handle, the plastic and aluminium parts, can be
removed with a moistened cloth (99% water +I % mild
detergent). Spirit or washing benzine (petroleum ether) can
be used to remove greasy dirt. The screen may be cleaned
with water or washing benzine (but not with spirit (alcohol)
or solvents), it must then be wiped with a dry clean lint-free
cloth. Under no circumstances may the cleaning fluid get
into the instrument. The use of other cleaning agents can
attack the plastic and paint surfaces.

Switching over the mains/line voltage

The instrument is set for 220V (240V U.K.) line voltage on
delivery. It can be switched over to other voltages at the
fuse holder combined with the 3-pole appliance inlet at the

rear of the instrument. Firstly the fuse holder printed with
the voltage values is removed using a small screw driver
and - if required - provided with another fuse. Refer to the
table below for the prescribed value of the fuse. Then
replace the fuse holder so that the impressed white triangle
points to the desired voltage. Here pay attention that the
cover plate is also correctly engaged. The use of repaired
fuses or short circuiting the fuse holder is not allowed. Dam­age arising because of this is not covered by the guarantee.

Fuse type: Size 5 x 20 mm; 250 V-, C;
IEC 127, Sheet III; DIN 41 662 (possibly DIN
sheet 3).
Cutoff: time lag

Line voltage

llOV-flO%
125V- &IO%

22ov- &IO%
24OV- &IO%

(T).

Fuse rating
TO.63 A
TO.63 A

T0.315A

T0.315A

.41

571

M2

Subject to change

wlthout

notice

Type of Signal

All types of signals with a frequency spectrum below
60 MHz can be displayed on the HM 604. The display of sim-

ple electrical processes such as sinusoidal RF and AF sig­nals or ripple poses no problems. However, when square or

pulse-shaped signals are displayed it must be remembered
that their harmonic content must also be transmitted. In
this case, the bandwidth of the vertical amplifier must be
considerably higher than the repetition frequency of the sig-

nal. In view of this, accurate evaluation of such signals with
the HM 604 is only possible up to a maximum repetition rate

of

6MHz.

Operating problems can sometimes occur when
composite signals are to be displayed, especially if they do
not contain any suitable level components and repetition

frequency which can be used for triggering. This occurs, for

example, with burst signals. To obtain a stably triggered dis­play in these cases, it may be necessary to use Normal Trig­gering, HOLD OFF time control, and/or
control.

TIME/DIV.

variable

If a sinusoidal waveform, displayed on the oscilloscope sc­reen, is to be converted into an effective (rms) value, the re­sulting peak-to-peak value must be divided by

2x-

=

2.83. Conversely, it should be observed that sinusoidal volt­ages indicated in

V,,,

(V,,,)

have 2.83 times the potential dif­ference in V,,. The relationship between the different volt­age magnitudes can be seen from the following figure.

Voltage values of a sine curve

v

= effective value;

rms

V,,

= peak-to-peak value;

V,

= simple peak or crest value;

V,,,

= momentary value.

Video signals are easily triggerable by the aid of the active

TV sync separator (TV SEP. switch).

For optional operation as a DC or AC voltage amplifier, each

channel is provided with a DC-AC coupling switch. The DC

position should only be used with an attenuator probe or at
very low frequencies or if the determination of DC voltage
content of the signal is absolutely necessary.

However, when investigating very low-frequency pulses,

misleading ramp-offs may occur with AC coupling. In this

case, DC operation is to be preferred if the signal voltage is

not superimposed on a too high DC voltage level. Other­wise, a capacitor of adequate capacitance must be con-

nected before the input of the vertical amplifier (switched to

DC coupling). It should be remembered that this capacitor

must have a sufficiently high breakdown voltage. DC opera-

tion is also recommended for the display of logic and pulse

signals, particularly if their pulse duty factor changes perma-

nently during operation. Otherwise, the display will move

up and down with any change. DC voltages can only be

measured in the DC position.

Amplitude Measurements

The minimum signal voltage required at the vertical amplifier

input for a display of 1 cm is approximately

achieved with the attenuator control set at

7mV,,.

5mV/cm,

This is
its var-

iable control in the fully clockwise position and pulled

out. However, smaller signals than this may also be dis-

played. The deflection coefficients on the input attenuators
are indicated in

mV/cm

or V/cm (peak-to-peak value).

The magnitude of the applied voltage is ascertained by

multiplying the selected deflection coefficient by the

vertical display height in cm.

If an attenuator probe x 70 is used, a further multiplica­tion by a factor of 70 is required to ascertain the correct

voltage value.
For exact amplitude measurements the variable con-
trol on the attenuator switch must be set to its calibra-

ted detent CAL. When turning the variable control ccw

the sensitivity will be decreased by a factor of 2.5.

Therefore every intermediate value is possible within

the 7-2-5 sequence.

With direct connection to the vertical input, signals up to

4OOV,, may be displayed (attenuator set to

ZOV/cm,

vari­able control ccw).
When pulling the variable control knob (MAG x5), the sen-

sitivity is increased by a factor of 5. Hence follows a min. de­flection coefficient of 1

mV/cm

(reduced bandwidth).

In general electrical engineering, alternating voltage data
normally refers to effective values (rms = root-mean-
square value). However, for signal magnitudes and voltage
designations in oscilloscope measurements, the peak-to-
peakvoltage (V,,) value is applied. The latter corresponds to
the real potential difference between the most positive and
most negative points of a signal waveform.

Subject to change without notice

With the designations

H = display height in cm,

= signal voltage in

U

V,,

at the vertical input,
D = deflection coefficient in V/cm at attenuator switch,
the required quantity can be calculated from the two given
quantities:

=

D-H

U

H=;

D+

M3 604

However, these three values are not freely selectable. They
have to be within the following limits (trigger threshold, ac-

curacy of reading):

H between 0.5 and
U between 1
D between

5mV/cm

D between 1 mV/cm and

(with

pulled MAG x5 knob). As a rule, all signals to be displayed are periodically repeat-

mV,,

and 16OV,,,

8cm,

if possible 3.2 to

and

20V/cm

4V/cm

8cm,

in l-2-5 sequence.

in l-2-5 sequence

Examples:

Set deflection coefficient D = 50 mV/cm 2 0.05 V/cm,
observed display height H = 4.6 cm,

required voltage U =

Input voltage U =

5V,,,

0.05.4.6

= 0.23 V,,.

set deflection coefficient D = 1 V/cm,

required display height H = 5: 1 = 5cm

Signal voltage U =

22OV,,;2.fl=

622

V,,

(voltage > 16OV,,, with probe X 10 : U = 62.2 V,,),

desired display height H = min.

3.2cm,

max.

8cm.

max. deflection coefficient D = 62.2 : 3.2 = 19.4V/cm,
min. deflection coefficient D = 62.2 : 8 = 7.8V/cm,

adjusted deflection coefficient D =

If

the applied signal is superimposed on a DC (direct

lOV/cm

voltage) level the total value (DC + peak value of the al­ternating voltage) of the signal across the Y-input must
not exceed

*4OOV(see

figure). This same limit applies to
normal x 10 attenuator probes, the attenuation ratio of
which allows signal voltages up to approximately 1
to be evaluated. Voltages of up to approximately

,OOOV,,

2,4OOV,,

may be measured by using the HZ53 high voltage probe
which has an attenuation ratio of 100: 1. It should be noted
that its AC

peakvalue

is derated at higher frequencies. If a

nor­mal x 10 probe is used to measure high voltages there is the

risk that the compensation trimmer bridging the attenuator

series resistor will break down causing damage to the input
of the oscilloscope. However, if for example only the re­sidual ripple of a high voltage is to be displayed on the oscil-

loscope, a normal x 10 probe is sufficient. In this case, an ap­propriate high voltage capacitor (approx. 22-68nF) must be
connected in series with the input tip of the probe.

Voltage

’

DC +

AC,,,k

=

I

peak

F@u

AC

DC

DC

.-

/\

/

/

I

Total value of input voltage ’ -

The dotted line shows a voltage alternating at zero volt level. When superim-

posed a DC level, the addition of the positive peak and the DC voltage results
in the max. voltage (DC + AC,,,,).

4OOV,,,.

-.

-1

/

‘\

AC

\

\.

\

1

1’

/

!

/

’

\

\

Time

\

\

‘\

\

\

/

\,

It is very important that the oscilloscope input coupling is
set to DC, if an attenuator probe is used for voltages higher

than 400V (see page M6: Connection of Test Signal).

Time Measurements

ing processes and can also be designated as periods. The
number of periods per second is the recurrence frequency
or repetition rate. One or more signal periods or even part of
a period may be shown as a function of the adjustment of
the

TIMEIDIV.

DIV. switch are indicated in s/cm,

cordingly, the dial is subdivided into three sectors. The du­ration of a signal period or a portion of the waveform is
ascertained by multiplying the relevant time (horizon-

tal distance in cm) by the time coefficient selected on
the

TIME/DIV.

knob on the
detent CAL. for accurate measurement (arrow horizontal

and pointing to the right).
With the designations

L

= displayed wave length in cm of one period,

T = time in seconds for one period,

F

= recurrence frequency in Hz of the signal,

T,

= time coefficient in s/cm on

and the relation F =
stated

:

T =

L.T,

F

-

=

L.Tc

With X-MAG.

be divided by 10.

However, these four values are not freely selectable. They
have to be within the following’limits:

L

between 0.2 and 1 Ocm, if possible 4 to 1 Ocm,

T between 5 ns and 1 OS,

F

between 0.1 Hz and 60 MHz,

T,

between

(with X MAG. x 10

T,

between 5 ns/cm and

(with pushed X MAG.

Examples:

Displayed wavelength L = 7 cm,

set time coefficient T, = 0.5 ps/cm,

required period T =

c

required rec. freq. F = 1:(3.5.1

/

Signal period T =
set time coefficient T, = 0.2 s/cm,

required wavelength L = 0.5 : 0.2 =

switch. The time coefficients on the TIME/

ms/cm,

and ps/cm. Ac-

switch. The time variable control (small

TIME/DIV.

switch) must be in its calibrated

timebase

l/T,

the following equations can be

1

L

xl0

button depressed the T, value must

50ns/cm

and 1 s/cm in l-2-5 sequence

=

1

F.Tc

in out position), and

lOOms/cm

x10

7.0.5.1

in l-2-5 sequence

button).

O-” =

3.5~s

OP6)

= 286

0.5s,

2.5cm.

switch

kHz.

T,

T,

=

=

;

&

.

M4 604

Subject to change without notice

Displayed ripple wavelength L = 1 cm,
set time coefficient T, = 10 ms/cm,
required ripple freq. F = 1 : (1 .10.10-3) = 100Hz.

If magnification is used, this product must be divided by 10.
The

fall

time of a pulse can also be measured by using this

method.

TV-line frequency F = 15 625 Hz,

set time coefficient T, = 10 @cm,
required wavelength L = 1: (15 625.1

Sine wavelength L = min.

Frequency F = 1
max. time coefficient T, = 1 :
min. time coefficient T, = 1

set time coefficient T, = 0.2
required wavelength L = 1: (1

Displayed wavelength L =
set time coefficient T, = 0.5

pressed MAG X 10 button: T, = 0.05
required rec. freq. F = 1: (0.8.0.05.1
required period T = 1: (25.1

If the time is relatively short as compared with the complete
signal period, an expanded time scale should always be
applied (X MAG
tained time values have to be divided by

intervals at optional points of the signal can be measured

more exactly with the aid of the sweep delay. With it, the
display and measurement of time intervals, which are smal-

ler than 1 % of the full signal period, are possible. The small­est measurable time interval is, on the whole, dependent on
the obtainable brightness of the CRT. The limit is an expan­sion of approximately 1000 times. Using a Viewing Hood

HZ47, more expansion is possible, provided that the time
coefficient set on the

S@cm

basic period. Otherwise, the fastest sweep speed deter-

mines the greatest possible expansion.

When investigating pulse or square waveforms, the critical
feature is the
transients, ramp-offs, and bandwidth limits do not unduly

influence the measuring accuracy, the

measured between 10% and 90% of the vertical pulse

height. For peak-to-peak signal amplitude of
which are symmetrically adjusted to the horizontal center

line, the internal graticule of the CRT has two horizontal dot­ted lines

tenuator switch with its variable control together with the

Y-POS. control so that the pulse height is precisely aligned

with the 0 and 100 % lines. The 10 % and 90 % points of the

signal will now coincide with the two lines, which have a

distance of

additional subdivision of

the product of the horizontal distance in cm between
these two coincidence points and the time coefficient
setting.

(and using the X MAG x 10 facility) for the signal’s

risetime

&2.4cm

f2.4cm

kHz,

x10

from the center line. Adjust the Y at-

4cm,

max. 1 Ocm,

(4.1 03)

:(I O-1 03)

ms/cm,

03-

0.8cm,
ys/cm,

06)

= 40 ns.

button pushed). In this case, the ascer-

TIME/DIV.

of the voltage step. To ensure that

from the horizontal center line and an

0.2cm.

The

0p5)

=

6.4cm.

=

0.25ms/cm,

= 0.1

m&m,

0.2 - 1

0p3)

= 5cm.

@cm,

Ov6)

= 25 MHz,

70.

Very small time

switch is greater than

risetime

risetime

is generally

6cm

height,

is given by

100%

90%

-I

qot t-

The above figure shows correct positioning of the oscillo­scope trace for accurate

With a time coefficient of O.O5ys/cm and pushed X MAG

x10

button the example shown in the above figure results

in a measured total

ttor

=

1.6cm.O.O5@cm:

When very fast risetimes are being measured, the rise-
times of the oscilloscope amplifier and the attenuator probe
have to be deducted from the measured time value. The

risetime

formula.

In this
of the oscilloscope amplifier (approx. 5.8ns), and t, the

risetime

then t,,, can be taken as the
lation is unnecessary.

Calculation of the example in
signal

of the signal can be calculated using the following

t,

=

v

ttot2 - t

ttot

is the total measured risetime,

of the probe (e.g. = 2 ns). If

risetime

t,

= V 8* -

risetime

risetime

2 -

osc

5.8* - 2*

measurement.

of

10 = 8ns

t

2

P

to,,

is the

ttot

is greater than 42 ns,

risetime

= 5.1 ns

of the pulse, and calcu-

tie

figure above results in a

risetime

Connection of Test Signal

Caution: When connecting unknown signals to the oscillo-

scope input, always use automatic triggering and set the

DC-AC input coupling switch to AC. The attenuator switch

should initially be set to POV/cm.

Sometimes the trace will disappear after an input signal has

been applied. The attenuator switch must then be turned

back to the left, until thevertical signal height is

With a

probe must be inserted before the oscilloscope’s vertical

input. If, after applying the signal, the trace is nearly

blanked, the period of the signal is probably substantially

signa!

amplitude greater than 16OV,,, an attenuator

only3-8cm.

Subject to change

wlthout

notlce

longer than the set value on the
should be turned to the left to an adequately greater time
coefficient.

The signal to be displayed should be fed to the vertical input
of the oscilloscope by means of a shielded test cable, e.g.
the HZ32 or HZ34, or by a x 10 or x 100 attenuator probe.

The use of these shielded cables with high impedance cir-

cuits is only recommended for relatively low frequencies
(up to approx. 50kHz). For higher frequencies, and when
the signal source is of low impedance, a cable of matched
characteristic impedance (usually

In addition, and especially when investigating square or

pulse waveforms, a resistor equivalent to the characteristic

impedance of the cable must also be connected to the cable
directly at the input of the oscilloscope. When using a 509
cable, such as the HZ34, a

HZ22 is available from HAMEG. When investigating square
or pulse waveforms with fast risetimes, transient

phenomena on both the edge and top of the signal may be­come visible if the correct termination is not used. It must

be remembered that the
dissipate a maximum of 2 watts. This power consumption

is reached with 1

If a x 10 or x 100 attenuator probe is used, no termination is

necessary. In this case, the connecting cable is matched di-

rectly to the high impedance input of the oscilloscope.
When using attenuator probes even high internal imped-

ance sources are only slightly loaded by approximately

10 MQ I I 16 pF or 100 MQ I I7 pF respectively. Therefore,
when the voltage loss due to the attenuation of the probe

can be compensated by a higher sensitivity setting on the

HM 604, the probe should always be used. Also it should be

remembered that the series impedance of the probe pro­vides a certain amount of protection for the input of the os-

cilloscope amplifier. It should be noted that all attenuator

probes must be compensated in conjunction with the oscil-

loscope (see: Probe Adjustment, page M8).

If a x IO or x 100 attenuator probe is used at voltages

higher than 400 V, the DC input coupling must always

be set. With AC coupling, the attenuation is frequency-de-

pendent, the pulses displayed can exhibit ramp-off, DC-volt-

age contents are suppressed - but loads the respective

input coupling capacitor of the oscilloscope. The electric

strength of which is maximum 400V (DC + peak AC). For

the suppression of unwanted DC voltages, a capacitor of

adequate capacitance and electric strength may be con-

nected before the input tip of the probe (e.g. for ripple

measurements).

It is important to remember that when low voltage signals
are being investigated the position of the ground point on
the test circuit can be critical. This ground point should al­ways be located as close as possible to the measuring

point. If this is not done, serious signal deformation may

OV,,,

50R

5OQ

through-termination will only

or with

TIMEIDIV.

5OQ)

is recommended.

through-termination type

28V,,

sine signal.

switch. It

result from any spurious currents through the ground leads
or test chassis parts. This comment also applies to the
ground leads on attenuator probes which ideally should be
as short and as thick as possible. For connection of a probe
to a BNC socket, a BNC-adapter should be used. It forms
often a part of the probe accessory. Grounding and match­ing problems are then eliminated.
Hum or interference voltage appearing in the measuring cir­cuit (especially with a small deflection coefficient) is possi­bly caused by multiple grounding, because equalizing cur­rents can flow in the shielding of the measuring cables (volt­age drop between non-fused earthed conductors of other
line powered devices, which are connected to the oscillo­scope or test object, e.g. signal generators with anti-inter­ference capacitors).

Operating

For a better understanding of these Operating Instructions
the front panel picture at the end of these instructions can
be unfolded for reference alongside the text.

The front panel is subdivided into three sections according
to the various functions. The INTENS., FOCUS and TR
(trace rotation) controls are arranged on the left directly
below the screen of the cathode-ray tube (CRT). Continuing
towards the right are the horizontal magnification button (X
MAG. x10), the switch for calibrator frequency selection

(1

kHz/l

MHz) and calibrator output sockets

(CAL.). The COMPONENT TESTER pushbutton and its

measuring socket are located on the right side.
The X-Section, located on the upper right, next to the screen,
contains the red POWER pushbutton and indicating LED, all
controls for
zontal trace position (X-POS.), sweep delay (DELAY), TV
separator (TV SEP.) together with the field select button
(FIELD
doff adjustment (HOLD OFF).
The lower Y-Section contains the controls for the vertical
deflection system. On the right and left in this section are lo­cated: vertical input connector, DC-AC-GD input coupling

slide switch, Y-POS. control, INVERT pushbutton, at­tenuator switch with variable control, and ground jack. All
these controls and connectors exist in duplicate for each of
the Channels I and II. Three pushbuttons for selecting the

operating mode are arranged below the attenuator

switches: CH
These are explained later.

The instrument is so designed that even incorrect operation

will not cause serious damage. The pushbuttons control

only minor functions, and it is recommended that before

commencement of operation all pushbuttons are in the

“out” position. After this the pushbuttons can be operated

depending upon the mode of operation required.

timebase

l/II),

the XYmode button (XV), and the knob for

l/II

(TIME/DIV.),

triggering (TRIG.), hori-

-TRIG l/II, DUAL and ADD.

0.2V/2V

hol-

M6 604

Subject to change without notice

The HM 604 accepts all signals from DC (direct voltage) up
to a frequency of at least
voltages the upper frequency limit will be

ever, in this higher frequency range the vertical display

height on the screen is limited to approx. 6cm. The time re­solution poses no problem. For example, with 100 MHz and
the fastest adjustable sweep rate (5ns/cm), one cycle will

be displayed every 2cm. The tolerance on indicated values

amounts to

be measured can therefore be determined relatively accu-

rately. However, from approximately 25 MHz upwards the
measuring error will increase as a result of loss of gain. At

40MHz

11 % should be added to the measured voltage at this fre­quency. As the bandwidth of the amplifiers differ (normally
between 65 and 70 MHz), the measured values in the upper

limit range cannot be defined exactly. Additionally, as al-

ready mentioned, for frequencies above
dynamic range of the display height steadily decreases. The
vertical amplifier is designed so that the transmission per­formance is not affected by its own overshoot.

f3%

in both deflection directions. All values to

this reduction is about 10%. Thus, approximately

60MHz (-3dB).

For

80MHz.

60MHz

sinewave

How-

the

First Time Operation

Check that the instrument is set to the correct mains/

line voltage. (Refer to page

Before applying power to the oscilloscope it is recom-

mended that the following simple procedures are per­formed:

-

Check that all pushbuttons are in the out position, i.e. re­leased.

-

Rotate the three variable controls with arrows to their

calibrated detent.

-

Set the variable controls with marker lines to their mid-

range position (marker lines pointing vertically).

-

The LEVEL control knob should be on its left stop (AT).

-

The three lever switches in the X-Section should be set

to their uppermost position.

-

Both input coupling slide switches for CH.1 and

the Y-Section should be set to the GD position.

Switch on the oscilloscope by depressing the red POWER

pushbutton. An LED will illuminate to indicate working

order. The trace, displaying one baseline, should be visible

after a short warm-up period of 10 seconds. Adjust

and X-POS. controls to center the baseline. Adjust

TENS. (intensity) and FOCUS controls for medium bright-

ness and optimum sharpness of the trace. The oscilloscope

is now ready for use.

If only a spot appears (CAUTION! CRT phosphor can be
damaged.), reduce the intensity immediately and check
that the X-Y pushbutton is in the released (out) position. If
the trace is not visible, check the correct positions of all

knobs and switches (particularly LEVEL knob in AT position

and DELAY MODE lever switch to OFF).

M2).

CH.11

Y-P0S.I

IN-

in

To obtain the maximum life from the cathode-ray tube, the
minimum intensity setting necessary for the measurement
in hand and the ambient light conditions should be used.

Particular care is required when a single spot is dis­played, as a very high intensity setting may cause damage

to the fluorescent screen of the CRT. Switching the oscillo­scope off and on at short intervals stresses the cathode of
the CRT and should therefore be avoided.

Trace Rotation TR

In spite of Mumetal-shielding of the CRT, effects of the
earth’s magnetic field on the horizontal trace position
cannot be completely avoided. This is dependent upon

the orientation of the oscilloscope on the place of work.

A centred trace may not align exactly with the horizon-

tal center line of the graticule. A few degrees of mis­alignment can be corrected by a potentiometer acessi-
ble through an opening on the front panel marked

TR.

DC Balance Adjustment

The vertical preamplifiers for

matched dual
After long periods of use the FET characteristics may

change which can alter the DC balance of the vertical

amplifier. A quick check of DC Balance can be made on each

channel by pulling the fine amplitude control MAG x5 and

pushing it back. If the trace moves from the vertical position

(up or down) more than 1 mm, the DC Balance will require

readjustment. This check should be made after a 20-minute
warm-up period.

FETs

connected as input source followers.

Adjustment procedure

The following instructions should be performed to obtain

the correct DC balance adjustment of both channels.

-

Remove all input cables and adjust oscilloscope controls

to display the baseline.

-

Center the baseline using Y-POS. and X-POS. controls.

-

Set attenuator switches to
switches to GD.

-

Release all pushbuttons in the Y-Section.

-

Place the oscilloscope so that it rests
right position) and locate DC balance adjustment poten­tiometer access holes - marked

CH.11 -

which are found underneath the instrument.

-

Insert a screwdriver (blade approx.
20 mm) in
is located behind the hole.

-

Pull and push the
just balance pot so that the baseline no longer moves up
or down. When the trace remains steady, correction of

CH.1

-

Depress CH I/II-TRIG.

procedure for

CH.1

hole. A plastic guide with slotted bottom

is completed.

CH.II.

CH.1

variable control MAG x5 and ad-

CH.1

and

CH.11

contain

5mV/cm

l/II

button. Repeat adjustment

and input coupling

firmlyon

CH.1

its back (up-

DC-BALANCE

3mm,

length min.

Subject to change without notice

M7 604

Use and Compensation of Probes

To

display an undistorted waveform on an oscilloscope, the
probe must be matched to the individual input impedance
of the vertical amplifier.

small insulated non-metallic screwdriver or trimming tool,
the trimmer has to be adjusted slowly until the tops of the
squarewave signal are exactly parallel to the horizontal
graticule lines. (See Fig. above for 1
amplitude shown should be 4cm + 1.2 mm (= 3 %), During
this adjustment, the signal edges will remain invisible.

The HM604’s built-in calibration generator provides a

squarewave signal with a very low
switch-selectable frequencies of approx.
at two output sockets below the CRT screen. One output

provides

0.2V,, *I

% for 10: 1 probes, and

present at the other, for 100: 1 probes.

risetime

1 kHz and 1

(<5ns), and

MHz

2V,,

+I % are

Adjustment at 1 MHz

Probes
They incorporate resonance deemphasizing networks
trimmer in conjunction with inductances and capacitors)
which permit - for the first time - probe compensation in
the range of the upper frequency limit of the vertical oscillo-

When the attenuator switches are set to 5mV/cm vertical

deflection coefficient, these calibration voltages corre­spond to a screen amplitude of

The output sockets have an internal diameter of

accommodate the internationally accepted shielding tube
diameter of modern

Modular

4cm.

Probes and F-series

4.9mm

slimline

probes. Only this type of construction ensures the
extremely short ground connections which are essential for
an undistorted waveform reproduction of non-sinusoidal

scope amplifier. Only this compensative adjustment
ensures optimum utilisation of the full bandwidth, together

with constant group delay at the high frequency end,

thereby reducing characteristic transient-distortion near the

to

leading signal edge (e.g. overshoot, rounding, ringing, holes

or bumps) to an absolute minimum.

Using the probes HZ51, 52, and 54, the full bandwidth of
the HM 604 can be utilized without risk of unwanted wave­form distortion.

high frequency signals.

Prerequisite for this HF-adjustment is a squarewave

Adjustment at 1

The C-trimmer adjustment compensates the capacitive

loading on the oscilloscope input (approx.

HM604). By this adjustment, the capacitive division

assumes the same division ratio as the ohmic voltage

kHz

3OpF

with the

generator with fast

impedance (approx.
quency of approx. 1 MHz. The calibrator output of the

HM604 meets these requirements when the pushbutton

1 MHz is depressed.

divider to ensure an equal division ratio for high and low fre­quencies, as for DC. (For

set to 1: 1, this adjustment is neither required nor possible).

A baseline exactly parallel to the horizontal graticule lines is

a major condition for accurate probe adjustments. (See also

‘Trace Rotation

TR’,

Connect the probes (Types HZ51, 52, 53,

CH.1 input. All pushbuttons should be released (in the ‘out’

position), and all push-pull knobs pushed ‘in’. Set the input

coupling switch to DC, the attenuator switch to 5mV/cm,

and the

controls to CAL. position. Plug the probe tip into the appro­priate calibrator output socket, i.e. IO:1 probes into the

0.2V

1

TIME/DIV.

socket, 100: 1 probes into the 2.OV socket.

kHz

incorrect correct

Approximately 2 complete waveform periods are displayed
on the CRT screen. Now the compensation trimmer has to

be adjusted. Normally, this trimmer is located in the probe

1: 1

page M7.)

switch to

probes or switchable probes

54,

or HZ37) to

0.2ms/cm,

and all variable

incorrect

Connect the probe

the calibrator pushbutton

should be released (‘out’ position). Set the input coupling

switch to DC, attenuator switch to

DIV. switch to 0.1

position.

Insert the probe tip into the output socket marked
waveform will be displayed on the CRT screen, with leading
and trailing edges clearly visible. For the HF-adjustment
now to be performed, it will be necessary to observe the ris-

ing edge as well as the upper left corner of the pulse top. To
gain access to the HF-compensation trimmer, the plastic
cover of the probe connecting box has to be slid off after

unscrewing the probe cable. The connecting boxes of the

HZ51 and HZ54 contain one R-trimmer screw, each, while
that of the HZ52 provides three. These R-trimmers have to

be adjusted in

top is as straight as possible. Overshoot or excessive round-

ing are unacceptable. This is relatively easy on the HZ51

and HZ54, but slightly more difficult on the HZ52. The rising

edge should be as steep as possible, with the pulse top

remaining as straight and horizontal as possible.

head. On the 100: 1 probe HZ53, however, it is located in

the connecting box at the other end of the cable. Using a

On the HZ52, each of the three trimmers has a clearly

kHz.)

The signal

HZ51,52,

and 54 will also allow for HF-adjustments.

risetime

(HZ51,52,

l&cm.

(typical 4ns). and low output

5OQ).

providing

or 54) to CH.1 input. Depress

1MHz.

Set all variable controls to CAL.

0.2V

and 2V at a fre-

All other pushbuttons

5mV/cm,

and TIME/

such a manner that the beginning of the pulse

0.2V.

(R-

A

M8 604

Subject to change without notice

defined area of influence on the waveform shape (see Fig.),
offering the added advantage of being able to ‘straighten
out’ waveform aberrations near the leading edge.

The adjustment sequence must be followed in the order
described, i.e. first at 1
frequencies should not be used for timebase calibrations.
The pulse duty cycle deviates from 1 : 1 ratio.

Adjustment points of the probes

HZ51, HZ54

Prerequisites for precise and easy probe adjustments, as
well as checks of deflection coefficients, are straight hori­zontal pulse tops, calibrated pulse amplitude, and

osc.

I

Tz (I+)

1

CAL.

potential at the pulse base. Frequency and duty cycle are

relatively uncritical.

(NF) T,

response,
generator outputs are of particular importance.

kHz,

then at 1 MHz. The calibrator

zero-

For interpretations of transient

fast pulse risetimes and low-impedance

(I-F) T,

T3 T, T,

T,_:

alters the middle frequencies

Ti: alters the leading edge

T,: alters the lower frequencies

T,

(NF) 1

-

IOnskm

-

HZ52

T, (LF)

After completion of the HF-adjustment, the signal

amplitude displayed on the CRT screen should have the
same value as during the 1

kHz

adjustment.

Probes other than those mentioned above, normally have a
larger tip diameter and may not fit into the calibrator out­puts Whilst it is not difficult for an experienced operator to
build a suitable adapter, it should be pointed out that most
of these probes have a slower risetime with the effect that
the total bandwidth of scope together with probe may fall
far below that of the HM604. Furthermore, the

HF-adjust-

ment feature is nearly always missing so that waveform dis­tortion can not be entirely excluded.

Providing these essential features, as well as switch-select-

able output-frequencies, the calibrator of the HM 604 can,

under certain conditions, replace expensive squarewave

generators when testing or compensating

wideband-

attenuators or -amplifiers. In such a case, the input of an
appropriate circuit will be connected to one of the

CAL.-out-

puts via a suitable probe.

The voltage provided at a high-impedance input (I

5OpF)

will correspond to the division ratio of the probe used

(10:

1 =

20mV,,,

Suitable probes are

For low-impedance inputs (e.g. 50

100:

HZ51,

1 =

also

20mV,,

52, 53, and 54.

Q),

from 2V output).

a 1: 1 probe can be

MSJ

II

15-

employed which, however, must be fully terminated with a

5052

through-termination. Suitable probe types are HZ50
and HZ54. The latter must be switched to the 1: 1 position,
and the HF-trimmer in the connecting box turned fullycoun-
terclockwise.

When connected to the

0.2V

CAL. socket, and using the

HZ50, this arrangement will provide approx. 40mV,, at

50Q circuit input, and approx.

24mV,,

if the HZ54 is used.

The voltages given here will have larger tolerances than 1 %
since operation of a 1: 1 probe together with a

5OQ

load is

very uncommon.

incorrect

Adjustment
1 MHz

Subject to change without notice

correct

incorrect

Using the 2V CAL. socket under similar conditions is only
possible with the HZ54 probe. The potential obtained at the

5OQ

input will then be approx.

190mV,,,

but with almost
twice the risetime. Accurate readings of the available input
voltage can be shown directly on the HM604 when con-

necting a

5OQ

through-termination between the BNC plug

of the probe and the input of the oscilloscope.

Operating Modes of the Y Amplifier

The required operating modes are selected on three

pushbuttons located in the Y-Section. For Mono operation
all pushbuttons should be in the out position, the instru­ment is then operating on Channel/only.

M9

604

For Mono operation with Channel
pushbutton has to be pressed. When the DUAL button is
depressed, the HM604 is in
mode, the channels are displayed consecutively (alternate
mode). This mode is not suitable for the display of very low
frequency signals
or jump. Under these conditions,
depressed additionally selecting chopped mode. In this
position, both channels then share the trace during each
sweep period. For the display of high frequency signals, the
type of channel switching selected is less important.

To select the add mode only the ADD button should be
depressed. The signals on both channels are then added
together. If in this mode one channel is inverted (pushbut­ton INVERT depressed), then the difference between the
two channels is displayed. For both of these operating
modes, the vertical position of the trace depends on the set­ting of the Y-POS. controls of both channels.

(<l kHz),

as the tracewill appear to flicker

II,

the CH

Dualchannel

the ADD

l/II

-TRIG.

operation. In this

button should be

l/II

nal frequencies up to 120
quency the inherent phase difference between the vertical
and horizontal system makes accurate measurements dif­ficult. In this mode, one of the
horizontal deflection (X) while the other signal provides the

vertical deflection (Y).

0”

The phase angle between the two signals can be deter-

mined from the Lissajous pattern as follows:

cos

cp

35”

=

1/ I-@

kHz.

sin cp =

However, above this fre-

sinewave

signals provides

90” 180”

E

Differentialmeasurements

urement of the voltage drop across floating components
(both ends above ground). Two identical probes should be
used for both vertical inputs. Using a separate ground con­nection and notconnecting the probe or cable shields to the
circuit under test avoid ground loops (hum, common-mode
disturbances).

X-Y Operation

For X-Yoperation, the pushbutton in the X-Section marked
X-Y must be depressed. The X signal is then derived from
the

Channe///(HOR.

during X-Y operation is determined by the setting of

the Channel II input attenuator and variable control.

This means that the sensitivity ranges and input imped­ances are identical for both the X and Y axes. However, the

Y-POS.II

is taken over by the X-POS. control. It is important to note
that the X MAG.
the sweep, should not be operated in the X-Y mode. It

should also be noted that the bandwidth of the X amplifier

is approximately

phase difference between both axes is noticeable from

50

The Y-Input signal may be inverted by using the INVERT

(channel I) facility.

control is disconnected in this mode. Its function

kHz

upwards.

INP.). The calibration

x10

facility, normally used for expanding

5MHz

X-Y Phase Measurements

The X-Y phase measurement method can be used to meas-

ure the phase difference between two signals of the same ence signal occupies exactly 10 divisions (see next figure).

frequency. This provides a method of measurement for sig-

techniques allow direct meas-

ofthexsignal

(-3dB), and therefore an increase in

= arc sin

%J

This simple formula works for angles less than

independent from both deflection amplitudes on the
screen.

Caution!

If a single spot appears (both deflection voltages are missing)
reduce the intensity immediately, as a high intensity setting
may cause damage to the fluorescent screen of the CRT.

f

b

90”,

it is

Dual-Trace Phase Difference Measurements

Phase comparison between two signals of the same fre-

quency can be made using the dual-trace feature (DUAL

button depressed). This method of phase difference meas-

urement can be used up to the frequency limit of the vertical
system. To make the comparison, use the following proce­dure:

Set the Input Coupling switches to the same position, and
the CH. I/II-TRIG.

reference signal (Phase 0”) is connected. Select ALT. chan-

nel switching for frequencies above 1

frequencies below 1

time delay to connect the signals to the input connectors.

Set the Input Attenuator switches and the CH I and CH II var-

iable controls so that the displays are approximately equal

and about five divisions in amplitude. Set the TIME/DIV.

switch to a sweep rate which displays about one cycle of

the waveform. Move the waveforms to the

graticule with the Y-P0S.I and

Turn the Variable Time Control until one cycle of the refer-

Each division represents 36” of the cycle.

l/II

pushbutton to the channel where the

kHz,

and CHOP. for

kHz.

Use probes which have equal

center

Y-POS.II

controls.

of the

Ml0 604

Subject to change without notice

Figure 2

Amplitude modulated oscillation: F = 1 MHz; f = 1 kHz;

m = 50 %

; UT =

28.3

mVrms.

Dual-Trace Phase Difference Measurements

T =

Horizontal distance

t

= Horizontal distance of zero-crossing points (cm).

foroneperiod(cm).

Assume a horizontal difference of 3 divisions (t = 3cm) and
a period of

10

divisions (T = 1 Ocm), the phase difference

91

can be calculated using the following formula:

=

108”

l.885rad

or

arcg,

-2~t =$ a2~~

=f

respectively.

Measurement of an amplitude modulation

The momentary amplitude u at time t of a HF-carrier volt­age, which is amplitude modulated without distortion by a

sinusoidal AF voltage, is in accordance with the equation

u

=

U,.

sinQt

+

0,5m

. UT - cos(S&w)t -

where

= unmodulated carrier amplitude

U,
S2= 2~rF
0

=2nf

= angular carrier frequency

= modulation angular frequency

m= modulation factor (S 1 P 100

The lower side frequency F-fand the upper side frequency

F+f

arise because of the modulation apart from the carrier

frequency

F.

T

0,5m *

Figure 1
Amplitude and frequency spectrum for AM display (m = 50%)

UT

4

I

F-f F F+f

The display of the amplitude-modulated
evaluated with the oscilloscope provided the frequency
spectrum is inside the oscilloscope bandwidth. The time

base is set so that several cycles of the modulation fre­quency are visible. Strictly speaking, triggering should be ex­ternal with modulation frequency (from the AF generator or a
demodulator). However, internal triggering is frequently pos­sible with normal triggering using a suitable LEVEL setting
and possibly also using the time variable adjustment.

0,5m

- UT -

cos(l(r+o)t

%).

UT

0,5m

-

UT

4

HF

oscillation can be

Oscilloscope setting for a signal according to figure 2:

Depress no buttons.

TIM

E/DIV. :

0.2

Triggering: NORMAL with LEVEL-setting; internal (or

Y:

ms/div.

CH. I; 20mV/div; AC.

external) triggering.

If the two values
ulation factor is calculated from

a-

m =

­a+b

aand

b

resp. m =

bare read from the screen, the mod-

a*.

100

[%J

where a = UT (l+m) and b = UT (l-m).

The variable controls for amplitude and time can be set ar­bitrarily in the modulation factor measurement. Their posi­tion does not influence the result.

Triggering and Timebase

With the LEVEL knob in locked position (turned ccw to AT

position = automatic triggering), a baseline is displayed con-

tinuously even when no signal is present. In this position it is

possible to obtain stable displays of virtually all uncompli­cated, periodically repeating signals above 30 Hz. Adjust­ments of the

With normal triggering (LEVEL knob not in AT position) and

LEVEL adjustment, triggering of time/div. deflection can be
set in any point of a given signal. The triggering range which
can be set with the LEVEL control depends greatly on the

amplitude of the displayed signal. If it is less than 1 div, then
the range is quite small and performance of settings re­quires a delicate touch.

If the

LEVEL

ble.

In order to obtain a satisfactory stable display, the
must be triggered synchronously with the test signal. The
trigger signal can be derived from the test signal itself,
when internal triggering is selected, or from a frequency re­lated signal applied to the external trigger input.

timebase

then are limited to

timebase

setting.

control is incorrectly set, no trace will be visi-

timebase

Subject to change without notice

Ml1 604

Triggering can be selected on either the rising or falling edge
of the trigger signal depending on whether the SLOPE +/­pushbutton (next to
out position, triggering from the positive-going edge is
selected. The correct slope setting is important in obtaining
a display when only a portion of a cycle is being displayed.

With internal
the Y amplifier, the trigger signal is derived from the respec­tive channel in use. In the Dualchannelmode, the internal
trigger signal may be selected from either Channel I or

Channel//using the

sition, the trigger signal is derived from Channel I. However,

it is always preferable to trigger from the less complicated

signal.

With

internalalternate

X-Section depressed) in the DUAL channel alternate mode
of the Y amplifier, the trigger voltage is derived alternately

from Channel I and Channel

ticularly useful when two asynchronous signs/s are being

investigated. Normal triggering should be preferable in this
mode. The display of one signal only is not possible on the

alternate trigger mode.

For

exfernaltriggering,

tion must be depressed. The sync. signal

must then be fed to the TRIG. INP. input socket.

Coupling mode and frequency range of the trigger signal

are selected with the TRIG. lever switch in the X-Section for

internal and external triggering, provided that the TV SEP.

switch is in off position. The HM 604 has 4 coupling modes:
AC, DC, LF, HF. The AC coupling mode is mainly used. DC
trigger coupling is only recommended, when very low fre-

quency signals are being investigated and triggering at a
particular value is necessary, or when pulses, which sig­nificantly change in duty cycle during observation time,
have to be displayed. If DC coupling is selected, it is advisa­ble to use the normal triggering mode. In the HF coupling
mode, a high pass filter is switched into the trigger

amplifier. This filter cuts off the DC content of the trigger

signal and the lower frequency range.

LEVEL)is

triggering

in the out or in position. In the

in the Mono channel mode on

CHMI-TRIG.I/II

triggering (ALT pushbutton in the

the EXT. pushbutton in the X-Sec-

button; in the out po-

II.

This trigger mode is par-

(0.05V,,-0.5VJ

frequency component in complex waveforms. Therefore it

is especially suited for the measurement of small ripple volt-

ages from power supply rectifiers or of magnetic or static

leakage

In some countries, the standard power plug has symmetri-

cally arranged plugs (interchanging of Line and Neutral is

possible). In such cases, the SLOPE

indicate the wrong polarity compared with the display (trig­gering with falling edge instead of rising edge). For correc­tion, the power plug of the instrument has to be turned.

fields~in

a circuit.

+/-

pushbutton may

Triggering of video signals

The built-in active TV-Sync-Separator separates the sync
pulses from the video signal, permitting the display of dis­torted video signals either in line (H = horizontal) or in frame

(V = vertical) trigger mode. The TV lever switch has five po-

sitions: the OFF position is for normal operation.

The TV: H+ and H- positions (horizontal= line) and the
TV: V+ and V- (vertical
video triggering. In these four positions the TRIG. coupling
switch and the LEVEL control (in NORM. trigger mode) are

inoperative. In the TV: V+ and V- positions (frame trigger-

ing), a low-pass filter or integrating network is connected

into circuit, which forms a trigger pulse sequence with
frame frequency from thevertical sync pulses (incl. pre-and

postequalizing pulses).

When in V mode, it is possible to select field I or II by releas-

ing or depressing FIELD

For correct video triggering, the + and - positions at V and

H must be selected corresponding to the video input signal.

If the sync pulses are placed above the picture content, H+
or V+ should be in use. For sync pulses below the picture
content of the input signal, correct triggering, without any
influence from changing picture contents, will be possible
only in V- or H-setting. The INVERT pushbutton only
changes the display on the CRT, not the input signal.

=frame)

l/II

pushbutton.

positions are used for

In the LF coupling mode, a low-pass
the trigger amplifier. This filter cuts off any amplifier noise
and the frequency range of the trigger signal above 50

For the purpose of line triggering (TRIG. lever switch in the
X-Section) to N, a (divided) secondary voltage of the power
transformer is used as a trigger signal. This trigger mode is

independent of the signal amplitude or display height and al-

lows a display below the (internal) trigger threshold. Line
triggering is recommended for all signals which are time-re-

lated (multiple or submultiple) to the mains/line frequency
or when it is desirable to provide a stable display of a line-

Ml2 604

filter

is switched into

kHz.

In TV: H trigger mode, the trigger point lies on the starting

edge of a sync pulse if SLOPE button is in + position. As

mentioned before, in TV: V mode an integrating network is
additionally added to the sync separator which delays the
formed trigger pulse by about 50~s.

Video signals are triggered in the automatic mode. There­fore the adjustment of the trigger point is superfluous. The

internal triggering is virtually independent of the display

height, which may differ from 0.8 to 8div. As opposed to AT

mode, when in normal mode, the screen is blanked without

signal at the input (turning the LEVEL knob is ineffectual).

Subject to change without notice

Function of var. HOLD-OFF control

If it is found that a trigger point cannot be located on ex­tremely complex signals even after repeated and careful ad­justment of the LEVEL control in the Norma/ Triggering

mode, a stable display may be obtained using the HOLD-
OFF control (in the X-Section). This facility varies the hold-
off time between two sweep periods up to the ratio >5 :
Pulses or other signal waveforms appearing during this off
period cannot trigger the timebase. Particularly with burst
signals or aperiodic pulse trains of the same amplitude, the
start of the sweep can be shifted to the optimum or re­quired moment. After specific use the HOLD-OFF control
should be re-set into its calibration detent min., otherwise
the brightness of the display is reduced drastically.

,_

~

heavy parts

cyc,e

“;e

displayed

In DEL. TRIG. mode

andN

SEP. switch in H or V position,
after delay triggering to the next following line is possible.
Therefore discrete lines are representable. The slope is ap­pointed by the TV+ or N- position of the delay switch.
When not in TV-trig. mode the susceptibility to interference
(sense) can be influenced (A = normal, v = reduced).
Operation of the sweep delay is relatively easy, as normally

1.

only 3 controls in the X-Section need to be used: the DELAY
operating mode lever switch (OFF-SEARCH-DELAY-DEL.
TRIG.), the DELAY rotary switch (delay time range), and its
variable control VAR. IO:1 (small knob on the DELAY
switch). The latter, a twenty-turn precision potentiometer
with overwind protection, can increase the delay time range
tenfold. An LED near the DELAY mode switch indicates the
operating mode.
For reliable operation of the sweep delay, it is recom­mended that the following procedure should always be
adopted; also reference to the accompanying figures will
be of assistance.

Figure 1

HOLD-‘OFF time

I

v

Fig. 1 shows a case where the HOLD-OFF knob is in the Xl position and var-

ious

different

observation unsuccessful.

Fig. 2 shows a case where only the desired parts of the signal are stably dis-

played.

waveforms are overlapped on the screen, making the signal

Sweep Delay / After Delay Triggering

With the sweep delay, the start of the sweep can be de-

layed from the trigger point by a selectable time (IOOns to
maximum 1 s). It is therefore possible to start the sweep at
practically any point of a waveform. The interval, which fol­lows the start of the sweep, can be greatly expanded by the
increase of the sweep speed. From the 5 p/cm
range downwards to slower sweep speeds, an expansion
of at least 100 times, and with the aid of the X MAG. x10 ex-
pansion of 1000 times, is possible. With time coefficients
higher than

5@cm,

the maximum expansion increases
proportionally. However, with increasing the expansion, the
display brightness decreases. Under very high ambient light
conditions a Viewing Hood like HZ47 can overcome this
problem. It should be noted that there are some difficulties
with higher expansions, if the test signal has inherent jitter.
To reduce or eliminate this jitter, expanded parts of a signal
can be triggered again “after delay” provided there is
another suitable edge (DEL. TRIG.).

TIMEIDIV.

MODE

TIME/DIV.

LED

:

NORM.

:

0.5

ms/cm

:

off

Initially, the sweep delay mode lever switch should be set in

the OFF position. In this mode, the complete waveform

under investigation will be displayed as for normal oscillo­scope operation. The mode indicator LED is not illuminated
in OFF mode. The time coefficient on the

TIME/DIV.

switch
is selected so that 1 to 3 basic periods of the signal are
displayed. A larger number unnecessarily decreases the
brightness and maximum expansion. The display of only a
portion of a period limits the choice of the expanded time in­terval and possibly complicates the triggering. On the other
hand, the range of 1 to 3 basic periods can always be set un­constrainedly with the

TIME/DIV.

switch. In doing so, the

x10 expansion must be switched off temporarily (X

MAG.

x10

button is in out position). In the X-Section, the
HOLD-OFF control should be set to min. and the variable
control to CAL.The LEVEL control is adjusted so that stable
triggering is ensured (TRIG. LED is illuminated).

The mode switch should now be set to the SEARCH posi­tion; it will be seen that the start of the display will shift to
the right. The amount of shift indicates the exact delay time.

Subject to change without notice

Ml3 604

If a display is not obtained in this mode, then a lower delay
time range should be selected. For example, when inves­tigating the waveform shown in the figures, a display could

not be obtained with a delay time setting of

IOms,

as the

display is completely blanked. However, as a result of set­ting the DELAY rotary switch to 0.1

ps,

the shifting is not

visible. The DELAY range switch should then be rotated
clockwise until the display starts just prior to the short time

interval to be investigated. The precise adjustment to the
start is done with the VAR.

1O:l

delay time control. The

rotating range of the latter has no stop. On the range limits
a certain snapping noise is audible. Initially, this control
should be set in the left start position. In the SEARCH

mode, the LED indicator will flash.

Figure 2

If the

timebase

sweep speed is increased (rotate TIME/
DIV. switch clockwise), then the short time interval will be
expanded. It may be found that, as the amount of expansion
is increased, the trace will tend to shift. If this happens, the
VAR. delay time control can be readjusted - also sub­sequently at any time - to enable the exact point of interest
to be displayed.

In the example shown in figure 4, it can be seen that an ex­pansion of
sweep speed from

x10

was obtained by increasing the

O.Sms/cm

to 5Ops/cm. Also the pre-

timebase

cise measurement for the delayed portion of the waveform
is possible. In the example, this was found to be

250~s

on
multiplication of the horizontal length in cm (of an optional
signal section) by the time coefficient just adjusted.

Figure

4

MODE
DELAY

range

TIME/DIV.

LED

Delay time = 2.5cm

: SEARCH
:lms

: 0.5

mskm

:

flashing

.

0.5mskm

= 1.25ms

In figure 2 it can be seen that the delay time is also measur­able as the blanked portion or apparent shift of the start of
the trace. This time can be determined by multiplication of

(the horizontal shifting in cm) by (the time coefficient set on
the

TIME/DR!.

switch).

Now the mode switch can be set to DELAY. In this mode,
the LED is permanently illuminated. The display will now

shift to the left and the trace will commence in the same po-

sition as for a normal display; however, the short time inter-

val under investigation now starts on the first or left vertical

graticule line.

Figure 3

MODE
DELAY

range

TIME/DIV.

LED

Expansion

T =

5cm. 50@cm

T-

:

DELAY

:lms

: 50

@cm

:

illuminated

:o.5~10-3:50~10-6=10

=

250~s

Operation of the sweep delay requires a constant trigger
point. All signals, which have a constant phase shift be­tween the expanded section and trigger point, pose no
problems. This means all electrical signal shapes, which
contain signal edges of the same polarity and with

trigger-

able level values, which are constantly repeated with the re­curring frequency.

If there is no constant phase shift, the triggering may fail
after switching from the SEARCH to DELAY position or
with changing of the time coefficient. It is best to attempt to
find a trigger point, which has a constant phase shift up to
the signal section to be expanded in the OFF mode. With

complicated composite signals, the display of the basic

period could become superimposed by other signal por­tions. These dissappear as a rule when the sweep is in-

creased. Otherwise, a stable expanded display is obtained

by adjusting the LEVEL and the variable sweep control or by

means of the HOLD-OFF control.

Ml4 604

MODE
DELAY

range

TIME/DIV.

LED

:

DELAY

:lms

:

0.5

ms/cm

:

illuminated

Using the X MAG.

desired signal section is possible without

x10

button, a tenfold expansion of the

any

change of trig­gering or timebase. This can be of assistance with compli­cated or difficult-to-trigger signals.

Subject to change without notice

Operation of the sweep delay needs some experience, par-

ticularly with composite signals. However, the display of

sections from simple signal waveforms is easily possible. It
is recommended to operate only the sequence

SEARCH-DELAY,

because otherwise location of the short

OFF-

time interval to be investigated will be relatively difficult.

and the timebase generator inoperative. A shortened hori­zontal trace will be observed. It is not necessary to discon­nect scope input cables unless in-circuit measurements are
to be carried out. In the
be operated are
controls and settings have no influence on the test operation.

The sweep delay facility can be used in the following

modes: Mono, Dual, and

Algebraic

Addition

(+l+ll).

For the component connection, two simple test leads with

4mm @ banana plugs, and with test prod, alligator clip or

sprung hook, are required. The test leads are connected to

Delay Mode Indication

the insulated CT socket and the adjacent ground socket in
the Y-Section. The component can be connected to the test

Both operating modes of the sweep delay are indicated

leads either way round.
with an LED, located to the right of the DELAY mode lever
switch. In
dication of the temporary operating state. The

SEARCH

position, the LED will flash. This is an in-

DELAY

posi-

After use, to return the oscilloscope to normal operation, re-

lease the
tion is indicated by constant lighting of the LED. However,

should this be noted, and normal operating mode is re­quired then the change-over of the lever switch to its

OFF

position has been overlooked. This could cause errors in dis­playing a signal by complete or partial blanking. This indica­tion, therefore, should be closely observed.

Test Procedure

Caution! Do not testanycomponent in live circuitry - re-

move all grounds, power and signals connected to the

component under test. Set up Component Tester as

stated above. Connect test leads

tested. Observe oscilloscope display.

CTmode,

INTENS.,

COMPONENT TESTER

the only controls which can

FOCUS,

pushbutton.

and

X-POS..

acoss

component to be

All other

Component Tester

General

The HM 604 has a built-in electronic Component Tester (ab­breviated CT), which is used for instant display of a test pat-

tern to indicate whether or not components are faulty. The

CT can be used for quick checks of semiconductors (e.g.
diodes and transistors), resistors, capacitors, and inductors.
Certain tests can also be made to integrated circuits. All
these components can be tested in and out of circuit.
The test principle is fascinatingly simple. The power trans­former of the oscilloscope delivers a sine voltage, which is

Only discharged capacitors should be tested!

A built-in quick-acting fuse protects the

scope against mis-operation, e.g. device under test not dis-

connected from mains/line supply. In that case the fuse will

blow. For fuse replacement the oscilloscope has to be

opened (see service instruction page Sl “Instrument Case

Removal”). The fuse is located on the bottom side of the in-

strument (close to the CT pushbutton). Make sure that only

fuses of the specified type are used for replacement:

5x20mm,

41661).
applied across the component under test and a built-in fixed
resistor. The sine voltage across the test object is used for
the horizontal deflection, and the voltage drop across the re­sistor (i.e. current through test object) is used for vertical de­flection of the oscilloscope. The test pattern shows a cur-

rent-voltage characteristic of the test object.

Since this circuit operates with mains/line frequency (50 or
60 Hz) and a voltage of

ing range of the

CTis

nent under test is limited to a range from

8.5V

max. (open circuit), the indicat-

limited. The impedance of the compo-

2OQ

to 4.7

Below and above these values, the test pattern shows only

short-circuit or open-circuit. For the interpretation of the dis-

played test pattern, these limits should always be borne in
mind. However, most electronic components can normally

Test Pattern Displays

Page M 18 shows typical test patterns displayed by the vari-

ous components under test.

-

-

Testing Resistors

If the test object has a linear ohmic resistance, both deflect­ing voltages are in the same phase. The test pattern ex­pected from a resistor is therefore a sloping straight line. The

kS2.

angle of slope is determined by the resistance of the resistor
under test. With high values of resistance, the slope will tend
towards the horizontal axis, and with low values, the slope
will move towards the vertical axis.

be tested without any restriction.

Values of resistance from 20Q to

Using the Component Tester
The CT is switched on by depressing the COMPONENT
TESTER

pushbutton. This makes the vertical preamplifier

mately evaluated. The determination of actual values will

come with experience, or by direct comparison with a com-

ponent of a known value.

CTand

the oscillo-

quick-acting,

Open circuit is indicated by a straight horizontal line.
Short circuit is shown by a straight vertical line.

25OV, C.

50mA

#.7&Q

(IEC

127/ll

or DIN

can be approxi-

Subject to change without notice

I

Ml5 604

Testing Capacitors and Inductors

Capacitors and inductors cause a phase difference be­tween current and voltage, and therefore between the X
and Y deflection, giving an ellipse-shaped display. The posi­tion and opening width of the ellipse will vary according to
the impedance value (at 50 or

60Hz)

of the component

under test.

A horizontal ellipse indicates a high impedance or a re­latively small capacitance or a relatively high induct­ance.

A vertical ellipse indicates a small impedance or a rela-

tively large capacitance or a relatively small induct­ance.

A sloping ellipse means that the component has a con­siderable ohmic resistance in addition to its reactance.

The values of capacitance of normal or electrolytic
capacitors from

U.If#to 1OUOpFcan

be displayed and ap­proximate values obtained. More precise measurement
can be obtained in a smaller range by comparing the
capacitor under test with a capacitor of known value. Induc­tive components (coils, transformers) can also be tested.
The determination of the value of inductance needs some
experience, because inductors have usually a higher ohmic
series resistance. However, the impedance value (at 50 or
60 Hz) of an inductor in the range from 20 S2 to 4.7 kQ can
easily be obtained or compared.

diodes. Possibly

only

a small portion of the knee is visible.

Z-

diodes always show their forward knee and, up to approx.

1 OV, their Z-breakdown, forms a second knee in the oppo-

site direction. A Z-breakdown voltage of more than

12V

can

not be displayed.

i

I’

I

-­I

Z-Diode 12 V

Cathode-Anode

(CT-GD)

Type:
Terminals:

Connections:

i

--

.t

I

Normal Diode HighVoltage Diode

Cathode-Anode

(CT-GD) (CT-GD)

-7

Cathode-Anode

i

I

The polarity of an unknown diode can be identified by com­parison with a known diode.

Testing Transistors

Three different tests can be made to transistors: base-emit-

ter, base-collector and emitter-collector. The resulting test
patterns are shown below.

The basic equivalent circuit of a transistor is a Z-diode be­tween base and emitter and a normal diode with reverse po­larity between base and collector in series connection.
There are three different test patterns:

N-P-N Transistor:

__+_

-+

Testing Semiconductors

Most semiconductor devices, such as diodes, Z-diodes,

transistors,

FETs

can be tested. The test pattern displays
vary according to the component type as shown in the fi­gures below.

The main characteristic displayed during semiconductor
testing is the voltage dependent knee caused by the junc­tion changing from the conducting state to the non conduct-

ing state. It should be noted that both the forward and the

reverse characteristic are displayed simultaneously. This is
always a two-terminal test, therefore testing of transistor
amplification is not possible, but testing of a single junction

is easily and quickly possible. Since the CT test voltage
applied is only very low (max.

8.5V,,,),

all sections of most
semiconductors can be tested without damage. However,
checking the breakdown or reverse voltage of high voltage
semiconductors is not possible. More important is testing
components for open or short-circuit, which from experi­ence is most frequently needed.

Testing Diodes

Diodes normally show at least their knee in the forward
characteristic. This is not valid for some high voltage diode

types, because they contain a series connection of several

I I

Terminals:

Connections:

P-N-PTransistor:

Terminals:
Connections:

-+-

I

b-e b-c

(CT-GD) (CT-GD)

.J__

I
I

e-c

(CT-GDI

1 \

I

CC;-:D,

For a transistor the figures b-e and b-c are important. The fi­gure e-c can vary; but a vertical line only shows short circuit
condition.

These transistor test patterns are valid in most cases, but
there are exceptions to the rule (e.g. Darlington,

FETs).

With
the CT, the distinction between a P-N-P to a N-P-N transis­tor is discernible. In case of doubt, comparison with a

known type is helpful. It should be noted that the same
socket connection (CTor ground) for the same terminal is

then absolutely necessary. A connection inversion effects a

rotation of the test pattern by 180 degrees round about the

center

point of the scope graticule.

Ml6 604

Subject to change without notice

Pay attention to the usual caution with single
ponents relating to static charge or frictional electricity!

MOS-com-

In-Circuit Tests

Caution! During in-circuittests make sure the circuit is
dead. No power from mains/line or battery and no signal
inputs are permitted. Remove all ground connections in­cluding Safety Earth (pull out power plug from outlet).
Remove all measuring cables including probes between
oscilloscope and circuit under test. Otherwise the con­nection of both CT test leads is not recommended.

In-circuit tests are possible in many cases. However, they are
not so well-defjned. This is caused by a shunt connection of
real or complex impedances - especially if they are of rela­tively low impedance at 50 or 60Hz - to the component
under test, often results differ greatly when compared with
single components. In case of doubt, one component termi­nal may be unsoldered. This terminal should then be con­nected to the insulated
the test pattern.
Another way is a test pattern comparison to an identical cir­cuit which is known to be operational (likewise without power
and any external connections). Using the test prods, identical
test points in each circuit can be checked, and a defect can be
determined quickly and easily. Possibly the device itself
under test contains a reference circuit (e.g. a second stereo
channel, push-pull amplifier, symmetrical bridge circuit),
which is not defective.
The test patterns on page M 18 show some typical displays
for in-circuit tests.

CTsocket

avoiding hum distortion of

Miscellaneous

A posifive-going sawtooth voltage of approximately

coincident with display’s sweep time is available at a BNC
output connector on the rear panel. This ramp output is
marked with M. The load impedance should not be less
than 10
not required, a capacitor should be connected in series with
the output. The ramp output can be used for different
measuring tasks in combination with the oscilloscope and
other instruments, triggering of signal sources, swept-fre­quency signal generators and so on.

The oscilloscope also contains a vertical output with BNC
connector marked Y on the rear panel. The output voltage is

?-50mV,,/cm

from the vertical amplifier like the trigger signal and it is
similarly switchable. Channel I or II is selected with the

CHI/II-TRIGI/II

switching (DUAL button in the Y-Section depressed) and al­ternate triggering (ALT. button in the X-Section depressed),
the vertical output is consecutively driven (in time with the
sweep period) from Channel I and Channel II. The vertical
output is not dependent on the vertical trace position. It
does not respond to the adjustment of the Y-P0S.I and Y-

POS.II

buttons. The vertical output is DC coupled and has approxi­mately zero level to ground. The bandwidth of the output is

approx. 60 MHz (with 50 Q termination).

k!2

II 47

pF.

If the DC potential of the ramp output is

display height (into

pushbutton. With alternate channel

controls and to the depressing one of the INVERT

5OQ).

It is picked off

SV,

Subject to change without notice

Ml7 604

Short

circuit

Resistor 510 Q

Single Transistors

Junction B-C

Test patterns

Junction B-E

Mains transformer prim.

Single Diodes

Z-diode under

8V

Capacitor 33

Z-diode beyond 12V

vF

Junction E-C

In-circuit Semiconductors

Diode paralleled by

6800

2 Diodes antiparallel

FET

Silicon diode Germanium diode

Rectifier

Thyristor G + A together

Ml8 604

Diode in series with 51 Q B-E paralleled by6808

B-E with 1 PF + 68052 Si-diode with 10

Subject to change without notice

PF

First Time Operation

Connect the instrument to power outlet. Switch on POWER pushbutton. No other button is depressed.
LED indicates operating condition.

Case, chassis, and all measuring connectors are connected
the Safety Earth Conductor (Safety Class I).

TRIG. selector switch to AC, TV SEP. switch to OFF, LEVEL knob in AT position (Automatic Triggering)

DELAY lever switch to OFF. and HOLD-OFF control

Adjust

INTENS.

Center trace on screen using X-POS. and Y-P0S.I controls. Then focus trace using FOCUS control.

control for average brightness.

Operating Modes of the Vertical System

Channel I: All pushbuttons in out position.
Channel

Channel

Channel
Channel - I + II

Channel + I -

II: CH

l/II

-TRIG.

I

and Channel

Alternate channel switching:
Chopped channel switching: DUAL

I+ II

(sum):ADD

(difference):ADD and

II

(difference):ADD and

l/II

button depressed.

II: DUAL

button depressed only.

button depressed.

ADD.

button in out position.

andADD

INVERT

INVERT

Trigger Modes

Automatic Triggering: LEVEL knob in

Normal

Triggering from positive-going signal edge: SLOPE
Triggering from negative-going signal edge: SLOPE

Internal triggering: select Channel with button
Internal alternate triggering: ALT button is depressed (only with alternate channel switching).
External triggering from

Line triggering:

Trigger coupling selected with
Video signals with line freq.: TV SEP. switch to H+ or H-.

Video signals with frame freq.: TV SEP. switch to V+ or V-.

First or second half of frame selection with
Pay attention to TRIG. indication LED!

Triggering:

This facility is important when only a portion of a cycle is being displayed.

External trigger signal: 50mV-0.5V,,, time-related to vertical input signal.

Trig. freq. range:

LEVEL

TRIG.

AC

turnded cw. Trace visible when triggered.

TRIG. INP.

selector switch in N position.

TRIG.

and

DC

to 20 MHz,

ATposition.

connector:

switch

HF

Short Instruction for HM604

to

min.

buttons depressed. Signals <I

(CH. I) buttons depressed.

(CH. II) buttons depressed.

Trace always visible.

+/-

button is in out position.

+/-

button depressed.

CH.I/II-TRIG.I/II.

EXT.

button depressed.

AC-DC-LF-HF.

above

20

MHz,

LF

below 50

FlELDI/II

switch.

kHz.

kHz

with CHOP.

Measuring

Connect test signal to
Compensate attenuator probe using
Select

AC

or DC input coupling. GD: Y amplifier is disconnected from input and grounded.
Adjust required display height of signal with attenuator switch and variable control.
Select sweep speed with
Adjust trigger point with
Calibrated amplitude measurement with attenuator variable control to
Calibrated time measurement with
Trigger complex or aperiodic signals using

Horizontal xl 0 expansion: X
External horizontal deflection: (X-Y operation) with X-Y button depressed (X input via

Sweep Delay Operation

OFF:
SEARCH:

DELAY:

DEL TRIG.:

normal oscilloscope operation. DELAY LED not illuminated.
use DELAY range switch and VAR.

displayed wave-form. DELAY LED flashing.

delayed signal now displayed. Expansion obtained by rotating
clockwise. Press X MAG. x10 button if necessary. DELAY LED illuminated.

After Delay Triggering; together with TV

Component Tester

Press

COMPONENT TESTER

/n-circuit test: Circuit under test must be disconnected to battery or power (pull out power plug),

signals and ground (earth). Remove all signal connections to HM 604 (cable, probe), then start testing.

CH.1

and/or

TIME/DIV.

LEVEL

CH.11

vertical input connector.

CAL.

square-wave signal.

switch and variable control.

control.

CAL.

TIME/DIV.

MAG.

x10

button. Connect both component terminals to

variable control to

HOLD-OFF

button depressed.

control in normal trigger mode.

1O:l

fine control to select point of interest on

SEP.:

CAL.

selection of trigger slope.

TIMEIDIV.

CTand

ground jacks.

CH.II).

switch

Subject to change without notice

Kl

604

Test Instructions

General

These Test Instructions are intended as an aid for checking
the most important characteristics of the HM 604 at regular

intervals without the need for expensive test equipment.

Resulting corrections and readjustments inside the instru­ment, detected by the following tests, are described in the
Service Instructions or on the Adjusting Plan. They should
only be undertaken by qualified personnel.

Astigmatism Check

Check whether the horizontal and vertical sharpness of the
display are equal. This is best seen by displaying a
wave signal with the repetition rate of approximately

1

at normal intensity, then check the sharpness of the vertical
edges. If it is possible to improve this vertical sharpness by
turning the FOCUS control, then an adjustment of the astig-

matism control is necessary. A potentiometer of 50 kQ (see
As with the First Time Operation instructions, care should
be taken that all knobs with

arrows

are

set to their calibrated
positions. None of the pushbuttons should be depressed.
LEVEL knob out in AT position, TRIG. selector switch to

Adjusting Plan) is provided inside the instrument for the cor-

rection of astigmatism (see Service Instructions). A certain
loss of marginal sharpness of the CRT is unavoidable; this is

due to the manufacturing process of the CRT.
AC, DELAY slide switch to OFF. It is recommended to
switch on the instrument for about 30 minutes prior to the

Symmetry and Drift of the Vertical Amplifier

commencement of any check.

Both of these characteristics are substantially determined

Cathode-Ray Tube: Brightness and Focus,
Linearity, Raster Distortions

Normally, the CRT of the HM 604 has very good brightness.

Any reduction of this brightness can only be judged visually.

However, decreased brightness may be the result of
reduced high voltage. This is easily
greatly increased sensitivity of the vertical amplifier. The
control range for maximum and minimum brightness (inten­sity) must be such that the beam just disappears before

reaching the left hand stop of the

larly when the X-Y button is depressed), while with the con­trol at the right hand stop the focus and the line width are
just acceptable.

recognized

INTENS.

by the

control (particu-

by the input stages of the amplifiers. The checking and

correction of the DC balance for the amplifiers should

be carried out as already described in the Operating
Instructions (page M 7).

The symmetry of Channel I and the vertical final amplifier
can be checked by inverting Channel I, depress INVERT
(CH I pushbutton). The vertical position of the trace should
not change by more than 5mm. However, a change of 1 cm
is just permissible. Larger deviations indicate that changes
have occurred in the amplifier.

A further check of the vertical amplifier symmetry is possi­ble by checking the control range of the
sine-wave signal of 1 O-l 00
input. When the Y-POS. control is then turned fully in both

With maximum intensity the

onnoaccountbe wisib/e.VisibledisplayfauItwithout input

signal: Bright dot on the left side

ness from left to right or shortening of the baseline. (Cause:

incorrect Unblanking Pulse.

timebase

-

or

fly-back must

-

decreasing bright-

directions from stop to stop with a display height of approx­imately
are visible should be approximately of the same height. Dif­ferences of up to 1 cm are permissible (input coupling
should be set to

It should be noted that with wide variations in brightness,

refocusing is always necessary. Moreover, with maximum

brightness, no “pumping” of the display must occur. If

pumping does occur, it is normally due to a fault in the regu-

lation circuitry for the high voltage supply. The presetting

pots for the high voltage circuit, minimum and maximum

intensity, are only accessible inside the instrument (see

Adjusting Plan and Service Instructions).

Checking the drift is relatively simple. Ten minutes after

switching on the instrument,

the horizontal

must not change by more than 5mm during the following
hour. Larger deviations generally result from different
characteristics of the dual

Y amplifier. To some extent, fluctuations in drift are caused

by offset current on the gate. The drift is too high, if the ver­A certain out-of-focus condition in the edge zone of the
screen must be accepted. It is limited by standards of the
CRT manufacturer. The same is valid for tolerances of the
orthogonality, the

undeflected

spot position, the non-linear-

tical trace position drifts by more than

the appropriate attenuator switch through all 12 steps.

Sometimes such effects occur after long periods of opera-

tion.

ity and the raster distortion in the marginal zone of the

screen in accordance with international standards (see CRT

Calibration of the Vertical Amplifier

data book). These limit values are strictly supervised by

HAMEG.

The selection of a cathode-ray tube without any

tolerances is practically impossible.

Two square-wave voltages of

present at the output sockets of the calibrator

square-

MHz. Focus the horizontal tops of the square-wave signal

Y-POS.

kHz

is applied to the amplifier

8cm,

the upper and lower positions of the trace that

controls. A

AC).

set the baseline exactly on

center

line of the graticule. The beam position

FETs

in both channel inputs to the

g.ZmV,

0.5mm

and 2

on turning

VP,, f

1 %

(CAL.).

are

If a

Subject to change without notice

Tl

604

direct connection is made between the 0.2 mV output and
the input of the vertical amplifier, the displayed signal in the

50mV/cm position (variable control to CAL.) should be

#cm

high (DC input coupling). Maximum deviations of

1.2 mm (3%) are permissible. If a x
between the
play height should result. With higher tolerances it should
first be investigated whether the cause lies, within the
amplifier or in the amplitude of the square-wave signal. On
occasions it is possible that the probe is faulty or incorrectly
compensated. If necessary the measuring amplifier can be
calibrated with an accurately known DC voltage (DC input
coupling). The trace position should then vary in accordance

with the deflection coefficient set.

With variable control at the attenuator switch fully counter­clockwise, the input sensitivity is decreased at least by the
factor 2.5 in each position. In the
displayed calibrator signal height should vary from 4cm to at
least 1.6cm.

2V-output

socket and Y input, the same dis-

lllprobe

50mVkm

is connected

position, the

attenuators and readjust them as necessary. A compen­sated

2:1

series attenuator is also necessary, and this
must be matched to the input impedance of the oscillo­scope. This attenuator can be made up locally. It is impor­tant that this attenuator is shielded. For local manufacture,
the electrical components required are a 1
tor and, in parallel with it, a trimmer 3-l 5 pF in parallel with
approx.
directly to the input connector of the vertical amplifier and
the other side is connected to the generator, if possible via
a low-capacitance coaxial cable. The series attenuator must
be matched to the input impedance of the oscilloscope in
the
coupling; square tops exactly horizontal; no ramp-off is per­mitted). This is achieved by adjusting the trimmer located in
the 2: 1 attenuator. Theshapeofthesguare-waveshould

then be the same in each input attenuator position.

Operating Modes:

ADD, CHOP.,

2OpF.

5mV/cm

One side of this parallel circuit is connected

position (variable control to CAL., DC input

CH.I/II -TRIG.I/II,

INV.I/II

and X-Y Operation

MS1 +I %

DUAL,

resis-

When pulling the Y-expansion x5 knob (MAG x5), the sen­sitivity is increased by the factor 5. In the
the displayed signal should change from 1 cm to 5cm by
pulling the MAG x5 knob.

O.PV/cm

position

Transmission Performance of the
Vertical Amplifier

The transient response and the delay distortion correction
can only be checked with the aid of a square-wave
generator with a fast
cable (e.g. HZ34) must be terminated at the vertical input of
the oscilloscope with a resistor equal to the characteristic

impedance of the cable (e.g. with HZ22). Checks should be
made at 1

deflection coefficient should be set at

input coupling (Y variable control in CAL. position). In so
doing, the square pulses must have a flat top without ramp-
off, spikes and glitches; no overshoot is permitted, espe­cially at 1 MHz and a display height of
time, the leading top corner of the pulse must not be

rounded. In general, no great changes occur after the instru-

ment has left the factory, and it is left to the operator’s dis­cretion whether this test is undertaken or not.

Of course, the quality of the transmission performance is

not only dependent on the vertical amplifier. The input

attenuators, located in the front of the amplifier, are fre-

quency-compensated in each position. Even small

capacitive changes can reduce the transmission perfor-

mance. Faults of this kind are as a rule most easily detected
with a square-wave signal with a low repetition rate (e.g.

1

kHz).

available, it is advisable to check at regular intervals the
deflection coefficients on all positions of the input

OOHz,

If a suitable generator with max. output of

1

risetime

kHz,

10

(max.

kHz,

100

5~).

The signal coaxial

kHz

and 1 MHz, the

5mV/cm

&km.

At the same

with DC

4OV,,

is

On depressing the DUAL pushbutton, two traces must
appear immediately. On actuation of the Y-POS. controls,
the trace positions should have no effect on each other.

Nevertheless, this cannot be entirely avoided, even in fully
serviceable instruments. When one trace is shifted verti­cally across the entire screen, the position of the other trace

must not vary by more than 0.5 mm.

A criterion in chopped operation is trace widening and
shadowing around and within the two traces in the upper or

lower region of the screen. Set

cm,

depress the DUAL and CHOP. pushbutton, set input
coupling of both channels to GD and advance the INTENS.
control fully clockwise. Adjust FOCUS for a sharp display.
With the Y-POS. controls shift one of the traces to a +2 cm,
the other to a -2cm vertical position from the horizontal

center

line of the graticule. Do not try to

chop frequency (500kHz)! Then alternately release and
depress the CHOP. pushbutton. Check for negligible trace
widening and periodic shadowing in the chopped mode.

It is important to note that in the

depressed) or the -I+11 difference mode INVERT (CH

button depressed in addition) the vertical position of the

trace can be adjusted by using both the Channel I and Chan-

nel II Y-POS. controls. If a trace is not visible in either these
modes, the overscanning

the trace.

In X-Y Operation (X-Y pushbutton depressed), the sensitiv­ity in both deflection directions will be the same. When the
signal from the built-in square-wave generator is applied to
the input of Channel II, then, as with Channel I in the vertical
direction, there must be a horizontal deflection of
when the deflection coefficient is set to

TIME/DIV.

I+11

LEDs

will indicate the position of

switch to 1

synchronize

add mode (only ADD

50mV/cm

ps/

the

#cm

position

I)

T2 604

Subject to change without notice

(variable control set to its CAL. position, X MAG. x10
released). The check of the mono channel display with the

CH

l/II

button is unnecessary; it is contained indirectly in the

tests above stated.

Triggering Checks

The internal trigger threshold is important as it determines

the display height from which a signal will be stably dis­played. It should be approx. 5mm for the HM 604. An
increased trigger sensitivity creates the risk of response to
the noise level in the trigger circuit, especially when the
sensitivity of the vertical input is increased by pulling the
MAG. x5 knob. This can produce double-triggering with
two out-of-phase traces. Alteration of the trigger threshold
is only possible internally. Checks can be made with any

sine-wave voltage between 50 Hz and 1 MHz. The LEVEL

knob should be in AT position. Following this it should be
ascertained whether the same trigger sensitivity is also pre­sent with Normal Triggering (LEVEL knob not in AT posi-

tion).

On depressing the SLOPE
sweep changes from the positive-going to the
going edge of the trigger signal.

Internally the HM 604 should trigger perfectly with
dal signals up to IOOMHz at a display height of approx.
5mm , when the HF trigger coupling mode is set.

For external triggering (EXT. button depressed), the EXT.
TRIG. input connector requires a signal voltage of at least

50mV,,,

Checking of W triggering is possible with a video signal of
switchable polarity. A check of both polarities in V and H

mode should be made.
The display should not shift horizontally during a change of
the trigger coupling from AC to DC with a sine-wave signal
without DC offset. The basic requirement for this is a cor-

rect DC Balance Adjustment on the input of the vertical

amplifier (see Operating Instructions, page M7).

which is in synchronism with the Y input signal.

+/-

button, the start of the

negative-

sinosoi-

Checking of the line/mains frequency triggering (50-60 Hz)

is possible, when the input signal is time-related (multiple or
submultiple) to the power line frequency (TRIG. selector
switch to LINE). In this trigger mode, there is no trigger
threshold. Even very small input signals are triggered stably

(e.g. ripple voltage). For this check, use an input of approx.

1 V. The displayed signal height can then be varied by turn-

ing the respective input attenuator switch and its variable

control.

Timebase

Before checking the
the trace length is
the potentiometer for sweep amplitude (see Adjusting

Plan). This adjustment should be made with the

switch in a mid position (i.e. 5pdcm). Prior to the com-

mencement of any check set the time variable control to

CAL. and the HOLD-OFF time control to min. The X MAG.

x10

button should be released. This condition should be
maintained until the variation ranges of these controls are
checked.

If a precise marker signal is not available for checking the

Timebase

generator may be used. Its frequency tolerance should not
be greater than &l %. The

HM 604 is given as
ter than this. For the simultaneous checking of

linearity and accuracy at least 10 oscillations, i.e. 1 cycle

everycm, should always be displayed. For precise determi-

nation, set the peak of the first marker or cycle peak exactly

behind the first vertical graticule line using the X-POS. con­trol. Deviation tendencies can be noted after some of the

marker or cycle peaks.
The 20 and

be checked very precisely with line frequency (5OHz only).

On the 20ms/cm range a cycle will be displayed every cm,

while on the

time coefficients, then an accurate sine-wave

lOms/cm

IOmskm

timebase

IUcm.

+3%,

ranges of the

it should be ascertained that

If not, it can be corrected with

timebase

but as a rule it is considerably bet-

range it will be every

accuracy of the

TIMEIDIV.

TIMEIDIV.

timebase

switch can

2cm.

In the

dualchannelmode

alternate channel switching and with alternate trigger­ing (ALT. button in the X-Section depressed), two non-fre-

quency related signals (e.g. mains/line frequency signal and
calibrator signal) should reliably be triggered internally
dependent on the positions of the
pushbuttons. In the dual channel mode with chop channel
switching and depressed ALT. button, only triggering from
Channel I should be possible. Periodical signal blanks (due
to the chopper frequency 0.5 MHz) should not be visible.

If both vertical inputs are AC coupled to the same signal and
both traces are brought to coincide exactly on the screen,

when working in the alternate dual channel mode, then

no change in display should be noticeable, when the ALT.
button is depressed or released.

Subject to change without notice

(DUAL button depressed) with

CHI/II-TRIG. l/II

The following table shows which frequencies are required

for the particular ranges.

1

s/cm

0.5 s/cm

0.2 s/cm

0.1 s/cm - 10 Hz

50

ms/cm -

20

ms/cm -

10

ms/cm -

5

ms/cm -

2

ms/cm -

1

ms/cm -

0.5ms/cm -

0.2

ms/cm -

1 Hz

-

2 Hz

-

-

5 Hz

20 Hz

50 Hz

100 Hz
200 Hz
500 Hz

1
2
5

kHz
kHz
kHz

0.1

ms/cm -

@cm - 20

50
20

f&cm ­@cm -

10

@cm -

5

yslcm

2

1

f&cm -

0.5

@cm -

0.2

f&cm -

0.1

0.05

10

kHz
kHz

50
100
200

-

f&cm - 10MHz

f&cm - 20MHz

500

1 MHz

2MHz
5MHz

kHz
kHz
kHz
kHz

The time variable control range can also be checked. The
sweep speed becomes slower by turning this variable con­trol counter-clockwise to its left stop. 2.5 cycles at least
every cm should be displayed (with X MAG.

released; measurement in the 5pdcm range).

When the X MAG.
cycle peak will be displayed every 10 cm +5 % (with variable
control in CAL. position; measurement in the 5pdcm

range). The tolerance is better measureable in the
range (one cycle every 1 cm).
Check the ramp output voltage on rear panel (BNC connector

marked by
ting: I V/cm; Timebase to one step slower sweep speed
than on the HM 604 under test. The latter must have no input
and no trigger voltage (free-running sweep; input coupling
switch to GD). The sawtooth voltage is applied with a BNC
cable without termination from the ramp output connector
to the input of the Test Scope. The Test Scope should show
a positive-going linear sawtooth with an amplitude of approx.

SV,,.

trol min.-max. can be checked. The hold-off time variation
cannot be measured precisely with this method, because the
unblanking pulse of the
the ramp width.

/w)

At the same time the function of the HOLD-OFF con-

x10

button is depressed, a marker or

with a Test Oscilloscope. Test Scope set-

timebase

generator is smaller than

x10

button

50ps/cm

Sweep Delay

When the Sweep DELAY mode lever switch is set to the OFF

mode, the delay should have no effect on the display of the

lkHz

calibration signal. When the Sweep Delay is set in
the SEARCH mode (refer to Sweep Delay Operating Instruc­tions), it is possible to check the delay time by means of a dis­tance measurement of the blanked baseline. For this, the

DELAY VAR. 1O:l control must be set to xl (rotate coun-

terclockwise until a snap noise is audible). When DELAY

mode is selected, the

without any blanking.

Over the full range of adjustment of the DELAY VAR.
10: 1 control, the displayed waveform of the calibration

signal should be shifted without any jitter, jumping or
intermittent blanking.

Control settings: Connect calibrator socket
CH.1 input connector, DC input coupling, deflection coeffi-

cient 50mV/cm, TRIG. selector switch to AC, time coeffi-

cient 1 mdcm, no pushbutton depressed, all controls in cali-

brated position, DELAY mode switch in OFF position, LEVEL
knob in AT position. Now the calibrator signal is displayed

with a signal height of 4cm and approx. 1 cycle per cm. After

switching to SEARCH, the mode indication lamp blinks. Set

the DELAY range switch to 1 ms. Rotate the DELAY VAR.

control until the left half of the display is blanked. The delay

time is now 5ms. After switching to DELAY, the display is

again fully visible. The DELAY mode LED is illuminated con­tinuously. The displayed signal can now be expanded. For
this purpose turn the TIME/DR/. switch clockwise to
cm. The expansion is now x200. With the DELAY VAR. con­trol, the nearest edge of the calibration signal can be brought
in the screen center and checked on the above-mentioned
criteria. With x200 expansion, the display brightness

traGe

reverts to the full

IOcm

display

(0.2V/l kHz)

to

5@

nor-

mally needs increasing (with

However, larger expansions than x200 are quite possible, but
the decrease of brightness and the jitter restricts the evalua­tion.
When switching to DEL. TRIG. positions, every slope is
accepted for triggering after the delay time has elapsed.

In TVSEP. mode condition, the slope can be chosen

INTENS.

and FOCUS control).

(+/-).

Component Tester

After pressing the
tal straight line has to appear immediately, when the CTsoc-
ket is open. The length of this trace should be approx. 8cm.
With connection of the
in the Y-Section, a vertical straight line with approx. 6cm
height should be displayed. The above stated measurements
have some tolerances. They are dependent among other
things on the mains/line voltage.

COMPONHVT

CTsocket

TESTER button, a horizon-

to one of the ground jacks

Trace Alignment

The CRT has an admissible angular deviation
the X deflection plane Dl-D2 and the horizontal center line of
the internal graticule. This deviation, due to tube producion
tolerances (and only important after changing the CRT), and
also the influence of the earth’s magnetic field, which is
dependent on the instrument’s North orientation, are cor-

rected by means of the TR potentiometer. In general, the
trace rotation range is asymmetric. It should be checked,
whether the baseline can be adjusted somewhat sloping to
both sides round about the horizontal center line of the
graticule. With the HM 604 in its closed case, an angle of rota­tion

AO.57”

(1 mm difference in elevation per
length) is sufficient for the compensation of the earth’s
magnetic field.

+5”

IOcm

between

graticule

Miscellaneous

Y output
A check of the Y output (rear panel) is possible on the screen

using the dual channel mode by means of the calibrator sig­nal. To this a connection is made from the calibrator socket

(0.2V/l kHz)

BNC cable and a 5OB through-termination - a second con­nection from the Y output to

tings:

switch to
coupling to GD, TIME/DIV. switch to

triggering (LEVEL knob in AT position), TRIG. selector to AC,

no button depressed. Now the square-wave signal is visible

with 4cm display height. With Y-P0S.I control, the tops of
the square-wave are adjusted to

center line of the graticule. Then the DUAL button has to be
pressed. The appearing second trace (without signal) is
adjusted to -2cm using the Y-POS.II control. Then the
input coupling is set to DC. Now the signal across the Y out­put appears with the same phase position as the calibrator
signal via Channel I. As well as the DC offset (e.g.

+80mV)

can be measured. In the example, the sensivity of the Y out­put can be calculated as

to the

CH.1

input connector and - using a BNC-

CH.11

CH.1

attenuator switch to

O.lV/cm, CH.1

the amplitude (e.g. 2cm P

input coupling to DC,

0.2V:4cm

input connector. Set-

50mV/cm, CH.11

attenuator

CH.11

0.5ms/cm,

+2cm

from the horizontal

0.2V,,)

=

SOmVkm.

automatic

+0.8cm &

of the Y output

input

CH.11

.

T4 604

Subject to change without notice

tor. Settings: CH.1 attenuator switch to 50mV/cm,
attenuator switch to O.lV/cm, CH.1 input coupling to DC,

CH.11

input coupling to GD,
cm, automatic triggering (LEVEL knob in AT position),
TRIG. selector to AC, no button depressed. Now the
square-wave signal is visible with

TIMEIDIV.

4cm

switch to

display height. With

CH.11

0.5ms/

Y-P0S.I control, the tops of the square-wave are adjusted

to

+2cm

from the horizontal

Y-POS.II

Now the signal across the Y output appears with the same
phase position as the calibrator signal via Channel I. As well

as the DC offset (e.g. +0_8cm P

(e.g. 2cm &
example, the sensivity of

0.2V:4cm

control. Then the

CH.11

input coupling is set to DC.

0.2V,,)

of the Y output can be measured. In the

=

SOmV/cm.

center

+80mV)

the Y output can be calculated as

the amplitude

2 modulation (optional)

Checking the blanking facility on the 2 modulation connec-

tor (rear panel) is possible with a sine- or square-wave

generator. The sine-wave generator requires an output volt­age control. The square-wave generator must deliver posi-

tive pulses to ground (chassis). Alternatively a small adjust-

able sine voltage from a (separate) power transformer may
be used. For the latter set the TIME/DIV. range to e.g.

lOms/cm. With the TIMEBASE variable control, the gap in

the baseline can be brought acceptably to a standstill. Line
frequency triggering is better (TRIG. selector switch to

The length ratio from bright to dark lines on the display is

dependent on the sine voltage amplitude. Without a mod­ulating generator, the function of the Z modulation can be
checked coarsely by short-circuiting the 2 connector. Then
the baseline is blanked fully.

N

.

Subject to change without notice

T5 604

Service Instructions

General

The following instructions are intended as an aid for the
electronic technician, who is carrying out readjustments on
the HM 604, if the nominal values do not meet the specifica­tions. These instructions primarily refer to those faults,
which were found after using the Test Instructions. How­ever, this work should only be carried out by properly qual­ified personnel. For any further technical information call or
write to HAMEG. Addresses are provided at the back of the
manual. It is recommended to use only the original packing
material, should the instrument be shipped to HAMEG for
service or repair (see also Warranty, page M2).

Instrument Case Removal

The rear cover can be taken off after unplugging the power
cord’s triple-contact connector and after two cross reces­sed pan head screws
have been removed. While the instrument case is firmly
held, the entire chassis with its front panel can withdrawn
forward. When the chassis is inserted into the case later on,
it should be noticed that the case has to fit under the flange
of the front panel. The same applies for the rear of the case,
on which the rear cover is put.

Caution
During opening or closing of the case, the instrument
must be disconnected from all power sources for
maintenance work or a change of parts or components.
If a measurement, trouble-shooting, or an adjustment
is unavoidable, this work must be done by a specialist,
who is familiar with the risk involved.

When the instrument is set into operation after the case

has been removed, attention must be paid to the accel­eration voltage for the CRT ­operating voltages for both final amplifier stages
together
CRT socket, on the upper and the lower horizontal

PC&,

neck. High voltages of max. 2000 V are at the
and FOCUS potentiometers. They are highly dangerous
and therefore precautions must be taken. It should be
noted furthermore that shorts occuring on different
points of the CRT high voltage and unblanking circuitry

will definitely damage some semiconductors. For the

same reason it is very risky to connect capacitors to
these points while the instrument is on.

Capacitors in the instrument

when the instrument is disconnected from all voltage
sources. Normally, the capacitors are discharged 6 sec­onds after switching ofi. However, with a defective
instrument an interruption of the load is possible.

14OV.

and on the lateral

(M4x30mm)

Potentials of these voltages are on the

PCB

with two washers on it

12.5kV -

directly beside the CRT

may

still be charged, even

and to the

INTENS.

Therefore,

nect one by one all terminals of the check strip across

1 kQ to ground (chassis) for a period of 1 second.
Handling of the CRT needs utmost caution. The glass
bulb must not be allowed - under any circumstances

to come into contact with hardened tools, nor should it

undergo local superheating (e.g. by soldering iron) or
local undercooling (e.g. by cryogenic-spray). We recom­mend the wearing of safety goggles (implosion danger).

atter

switching off, it is recommended to con-

Operating Voltages

Besides the two AC voltages for the CRT heating (6.3V) and
graticule illumination, Component Tester and line triggering

(12V)

there are eight electronically regulated DC operating

voltages generated

+

14OV. - 18OOV,

voltages are fixed voltages, except the +
adjusted. The variation of the fixed voltages greater than

+2

% from the nominal value indicates a fault. This voltage

is measured on the checkpoint strip (located on XY Board)
with reference to ground. Measurements of the high volt­age may only be accomplished by the use of a sufficient

highly resistive voltmeter

lutely sure that the electric strength of the voltmeter is suf-

ficiently high.

and + 10.4

(+12V, +5V, -5V, -12V. +68V,

kV).

These different operating

12V,

which can be

(>lOMQ).

You must make abso-

Minimum Brightness

The variable resistor VR601, located on the Z-PCB, is used

for this adjustment procedure. It may only be touched by a

properly insulating screwdriver (Caution! High voltage!).

Correct adjustment is achieved, when the trace can be

blanked while X-Y pushbutton is depressed and, in addi-

tion, when the requirement described in the Test Instruc-

tions are met.

-

Astigmatism control

The ratio of vertical and horizontal sharpness can be

adjusted by the variable resistor VR603, located on the

PCB (see Adjusting Plan). As a precaution however, the
voltage for the vertical deflecting plates (approx.
should firstly be checked, because this voltage will affect
the astigmastism correction. Use the 1 MHz square-wave
signal from the built-in calibrator via 10: 1 probe for this cor-

rection. Firstly adjust the sharpness of the horizontal
square-wave lines using the FOCUS control. The sharpness
of the verticallines should then be corrected with the aid of
the Astigm. pot VR626. Repeat the correction several
times in this sequence. Adjustment has been correctly car-

ried out when, on using FOCUS control only, the sharpness

is not improved in

eitherdirection.

-

Z-

+41.5V)

Subject to change without notice

Sl

604

Trouble-Shooting the Instrument

Replacement of Components and Parts

For this job, at least an isolating variable mains/line trans­former (protection class II), a signal generator, an adequate
precise multimeter, and, if possible, an oscilloscope are

needed. This last item is required for complex faults, which
can be traced by the display of signal or ripple voltages. As
noted before, the regulated high voltage and the supply
voltage for the final stages are highly dangerous. Therefore
it is recommended to use totally insulated extended
probe tips, when trouble-shooting the instrument. Acci­dental contact with dangerous voltage potentials is then
unlikely. Of course, these instructions cannot thoroughly
cover all kinds of faults. Some common-sense will certainly
be required, when a complex fault has to be investigated.

If trouble is suspected, visually inspect the instrument
thoroughly after removal of the case. Look for loose or badly
contacted or
ing). Check to see that all circuit board connections are mak­ing good contact and are not shorting to an adjacent circuit,

Especially inspect the connections between the
the power transformer, to front chassis parts, to CRT sock­et, to trace rotation coil (inside of CRT’s shielding), to the 3

BNC connectors at the rear chassis, and to the control
potentiometers and switches on top of and beneath both

main-PCBs. Furthermore, the soldering connections of the

transistors and Fixed Three-Terminal Regulators resp. on
the rear chassis. This visual inspection can lead to success

much more quickly than a systematic fault location using

measuring instruments. Prior to any extensive trouble-

shooting, also check the external power source.

If the instrument fails completely, the first and most impor­tant step - after checking the mains/line voltage and

power fuse - will be to measure the deflecting plate volt-

ages of the CRT. In almost any case, the faulty section can

be located. The sections represent:

1.

Vertical deflection.

2. Horizontal Deflection.

3.

CRTcircuit.

4. Power supply.

While the measurement takes place, the position controls

of both deflection devices must be in mid-position. When
the deflection devices are operating properly, the separate

voltages of each plate pair are almost equal then (Y

and X

If the separate voltages of a plate pair are very different, the

associated circuit must be faulty.

An absent trace in spite of correct plate voltages means a

fault in the CRT circuit. Missing deflection plate voltages is

probably caused by a defect in the power supply.

=67V).

discolored

components (caused by overheat-

PCBs,

to

=42V

For the replacement of parts and components use only
parts of the same or equivalent type. Resistors without

specific data in the diagrams have a power dissipation of

0.25 Watt and a tolerance of 2 %. Resistors in the high volt­age circuit must have sufficient electric strength.

Capacitors without a voltage value must be rated for an

operating voltage of 63V. The capacitance tolerance should

not exceed 20%. Many semiconductors are selected,
especially the gate-diodes 1 N4154, and all amplifier transis­tors, which are contained in push-pull circuits (including the

FETs).

If a selected semiconductor is defective, all gate-

diodes or both push-pull transistors of a stage should be

replaced by selected components, because otherwise
there are possibly deviations of the specified data or func­tions. The HAMEG Service Department can give you advice
for troubleshooting and replaceable parts. Replacement

parts can be ordered by letter or telephone from the nearest

HAMEG Service Office. Please supply the following infor-

mation: Instrument type and serial number, description of
the part (including function and location in the instrument),
quantity desired.

Replacement of the Power Transformer

Should it be necessary to replace the mains/line trans­former, the correct terminal sequence (color identification)
for primary and secondary windings must be followed (see

diagram “Power Supply” and the figure below). In addition,
the relevant Safety Regulations must be observed. Here,
we refer only to those requirements relative to the parts

conductively connected to the supply mains:

-

The construction of the instrument shall be such as to

prevent any short-circuiting or bridging of the insulation,
clearances or creepage distances between those parts
connected to the supply mains and any accessible con­ductive parts due to accidental loosening or freeing of
the wiring, screws, etc.

-

The rigidity of the mains wiring connections, which may

be subject to mechanical stresses, shall not be depend­ent upon the soldering alone. To meet this requirement,
the bare ends of the wires must be pushed through the
holes in the respective soldering tab, bent over with a
pair of pliers, and subsequently fixed by soldering.

-

The minimum cross section of the protective earth con-

nection between the instrument’s power inlet and the
connecting soldering tab on the rear chassis must be

0.81

mm2

in North America and 0.75mm2 in Western
Europe. The connecting soldering tab on the rear chassis
has to be secured mechanically against loosening (e.g.

with lock washer).

S2 604

Subject to change without notice

After replacing the power transformer, all remaining bits of

Adjustments

wire, solder and other foreign matter must be removed
from the

PCBs,

the vicinity of the power transformer and
from within the insulating connecting box by shaking,
brushing and blowing. Finally, the top plate of the insulating
connecting box has to be replaced. Before connecting the

instrument to the power supply, replace the possibly defec­tive fuse, press the POWER button and make sure that
there is an adequate insulation state between chassis

safety earth conductor) on the one hand, and the live/line

pin as well as the neutral pin, on the other. Only after proper

insulation has been established may further function tests
with open chassis follow, but with appropriate precaution-

ary measures.

Connection of the safety

-

earth pin via long sold.

tab to rear chassis

Appliance Inlet

As advised in the Operating, Test and Service Instructions,
small corrections and adjustments are easily carried out
with the aid of the Circuit Diagrams and Adjusting P/an.

However, a complete recalibration of the scope should not
be attempted by an inexperienced operator, but only some­one with sufficient expertise. Several precision measuring
instruments with cables and adapters are required, and only

(=

then should the pots and trimmers be readjusted, provided
that the result of each adjustment can be exactly deter-

mined. Thus for each operating mode and switch position,
a signal with the appropriate sine or square waveform, fre­quency, amplitude,

risetime

and duty cycle is required.

Safety Class

Plug with earthing contact

I

II

Rear View of Power Switch and Appliance
Inlet with Voltage Selector and Fuse

1

2+

2*

Pushbutton
power switch

4At24A

-_

I

250v

bk

_..
tl’

gr

(see diagram “POWER SUPPLY”)

J

Subject to change without notlce