HAMEG HM604-3 User Manual

Oscilloscope data sheet with technical details . .... 4

Operating Instructions

General Information ................................................. 5

Symbols ................................................................... 5

Use of tilt handle .....................................................5

Safety ....................................................................... 5

Operating conditions ............................................... 5

EMC .........................................................................6

Warranty .................................................................. 6

Maintenance ............................................................ 6

Protective Switch-Off .............................................. 6

Power supply ........................................................... 6

Type of signal voltage..............................................7

Amplitude Measurements ....................................... 7

Total value of input voltage .....................................8

Time Measurements ............................................... 8

Connection of Test Signal........................................9

First Time Operation..............................................1 0

Trace Rotation TR ..................................................10

Probe compensation and use ...............................11

Adjustment at 1kHz ...............................................11

Adjustment at 1MHz ............................................. 11

Operating modes of the vertical

amplifiers in Yt mode. ...........................................12

X-Y Operation .........................................................1 2

Phase comparison with Lissajous figures ............ 1 3

Phase difference measurement

in DUAL mode .......................................................13

Measurement of an............................................... 13

amplitude modulation ............................................1 3

Triggering and time base ....................................... 14

Automatic Peak-Triggering .................................... 14

Normal Triggering ..................................................15

Slope ...................................................................... 1 5

Trigger coupling ...................................................... 15

Line triggering (~) .................................................. 16

Alternate triggering................................................ 16

External triggering ................................................. 1 6

Trigger indicator ..................................................... 16

Holdoff-time adjustment ....................................... 16

Delay / After Delay Triggering ...............................17

AUTO SET ..............................................................18

SAVE/RECALL........................................................19

Component Tester ................................................. 1 9

Using the Component Tester ................................ 19

Test Procedure ....................................................... 19

Test Pattern Displays............................................. 19

Testing Resistors ................................................... 20

Testing Capacitors and Inductors..........................20

Testing Semiconductors ........................................2 0

Testing Diodes ....................................................... 20

St.1196-Hüb/Ros

Testing Transistors ................................................. 2 0

In-Circuit Tests ....................................................... 20

Table of contents

Oscilloscope

HM604-3

Test Instructions

General ...................................................................23

Astigmatism Check ............................................... 2 3

Symmetry and Drift of the Vertical Amplifier ....... 23

Calibration of the Vertical Amplifier ....................... 23

Transmission Performance of the

Vertical Amplifier.................................................... 2 3

Triggering Checks .................................................. 24

Timebase................................................................ 2 4

Holdoff time ...........................................................25

Component Tester ................................................. 2 5

Trace Alignment .....................................................25

Service Instructions

General ................................................................... 25

Instrument Case Removal .....................................25

Operating Voltages ................................................ 26

Maximum and Minimum Brightness .................... 26

Astigmatism control .............................................. 26

Trigger Threshold ................................................... 26

Trouble-Shooting the Instrument .......................... 26

Adjustments ........................................................... 26

RS232 Interface - Remote Control .......................27

Baud-Rate Setting ..................................................27

Data Communication ............................................. 27

Command definition .............................................. 27

Command Chart: ................................................... 27

Instrument Data Field with Single Commands ....28

Short instruction for HM304 ................................. 29

Switching on and initial setting ............................. 2 9

Vertical amplifier mode.......................................... 29

Triggering mode .....................................................29

Measurements ...................................................... 2 9

Component tester mode.......................................29

Front Panel Elements HM604-

(Brief Description - Front View) ............................. 30

3

Subject to change without notice

Printed in Germany

1

General information regarding the CE marking

HAMEG instruments fulfill the regulations of the EMC directive. The conformity test made by
HAMEG is based on the actual generic- and product standards. In cases where different limit
values are applicable, HAMEG applies the severer standard. For emission the limits for residential,
commercial and light industry are applied. Regarding the immunity (susceptibility) the limits for
industrial environment have been used.

The measuring- and data lines of the instrument have much influence on emmission and immunity
and therefore on meeting the acceptance limits. For different applications the lines and/or cables
used may be different. For measurement operation the following hints and conditions regarding
emission and immunity should be observed:

1. Data cables

For the connection between instruments resp. their interfaces and external devices, (computer,
printer etc.) sufficiently screened cables must be used. Without a special instruction in the manual
for a reduced cable length, the maximum cable length of a dataline must be less than 3 meters
long. If an interface has several connectors only one connector must have a connection to a cable.

Basically interconnections must have a double screening. For IEEE-bus purposes the double screened
cables HZ72S and HZ72L from HAMEG are suitable.

2. Signal cables

Basically test leads for signal interconnection between test point and instrument should be as
short as possible. Without instruction in the manual for a shorter length, signal lines must be less
than 3 meters long.

Signal lines must screened (coaxial cable - RG58/U). A proper ground connection is required. In
combination with signal generators double screened cables (RG223/U, RG214/U) must be used.

3. Influence on measuring instruments.

Under the presence of strong high frequency electric or magnetic fields, even with careful setup of
the measuring equipment an influence of such signals is unavoidable.
This will not cause damage or put the instrument out of operation. Small deviations of the measuring
value (reading) exceeding the instruments specifications may result from such conditions in individual
cases.

December 1995

HAMEG GmbH

KONFORMITÄTSERKLÄRUNG
DECLARATION OF CONFORMITY
DECLARATION DE CONFORMITE

Name und Adresse des Herstellers HAMEG GmbH
Manufacturer´s name and address Kelsterbacherstraße 15-19
Nom et adresse du fabricant D - 60528 Frankfurt

HAMEG S.a.r.l.
5, av de la République
F - 94800 Villejuif

Die HAMEG GmbH / HAMEG S.a.r.l bescheinigt die Konformität für das Produkt
The HAMEG GmbH / HAMEG S.a.r.l herewith declares conformity of the product
HAMEG GmbH / HAMEG S.a.r.l déclare la conformite du produit

®

Instruments

Bezeichnung / Product name / Designation:
Typ / Type / Type:
mit / with / avec:
Optionen / Options / Options:

mit den folgenden Bestimmungen / with applicable regulations / avec les directives suivantes

EMV Richtlinie 89/336/EWG ergänzt durch 91/263/EWG, 92/31/EWG
EMC Directive 89/336/EEC amended by 91/263/EWG, 92/31/EEC
Directive EMC 89/336/CEE amendée par 91/263/EWG, 92/31/CEE

Niederspannungsrichtlinie 73/23/EWG ergänzt durch 93/68/EWG
Low-Voltage Equipment Directive 73/23/EEC amended by 93/68/EEC
Directive des equipements basse tension 73/23/CEE amendée par 93/68/CEE

Angewendete harmonisierte Normen / Harmonized standards applied / Normes harmonisées utilisées

Sicherheit / Safety / Sécurité

EN 61010-1: 1993 / IEC (CEI) 1010-1: 1990 A 1: 1992 / VDE 0411: 1994
Überspannungskategorie / Overvoltage category / Catégorie de surtension: II
Verschmutzungsgrad / Degree of pollution / Degré de pollution: 2

Elektromagnetische Verträglichkeit / Electromagnetic compatibility / Compatibilité électromagnétique

Oszilloskop/Oscilloscope/Oscilloscope

HM604-3

-

-

EN 50082-2: 1995 / VDE 0839 T82-2

ENV 50140: 1993 / IEC (CEI) 1004-4-3: 1995 / VDE 0847 T3
ENV 50141: 1993 / IEC (CEI) 1000-4-6 / VDE 0843 / 6

EN 61000-4-2: 1995 / IEC (CEI) 1000-4-2: 1995 / VDE 0847 T4-2: Prüfschärfe / Level / Niveau = 2
EN 61000-4-4: 1995 / IEC (CEI) 1000-4-4: 1995 / VDE 0847 T4-4: Prüfschärfe / Level / Niveau = 3
EN 50081-1: 1992 / EN 55011: 1991 / CISPR11: 1991 / VDE0875 T11: 1992

Gruppe / group / groupe = 1, Klasse / Class / Classe = B

Datum /Date /Date Unterschrift / Signature /Signatur

14.12.1995

Dr. J. Herzog

Technical Manager

Directeur Technique

Specifications

Vertical Deflection

Operating modes: Channel I or II separate,

Channel I and II: alternate or chopped.
(0.5MHz chopper frequency, approx.)
Sum or difference with Ch. I and Ch. II
(both channels invertable).

XY-Mode: via channel I and channel II
Frequency range: 2xDC to 60MHz (-3dB)

Risetime: <5.9ns. Overshoot max. 1%.
Deflection coefficients: 14 calibrated steps
from 1mV/div. to 20V/div. (1-2-5 sequence)
with variable 2.5:1 up to 50V/div.

Accuracy in calibrated position:

1mV/div. to 2mV/div.: ±5% (0 to 10MHz (-3dB))

5mV/div. to 20V/div.: ±3%
Input impedance: 1MΩ II 20pF.
Input coupling: DC-AC-GD (ground).
Input voltage: max. 400V (DC + peak AC).

Delay line: approx. 90ns

Triggering

OSCILLOSCOPES

Automatic:
Normal with level control: DC-100MHz (≤0.5div.)

Slope: positive or negative,
ALT. Triggering; LED indicator for trigger action
Sources: Channel I or II, CH. I alternating CH II,

Coupling: AC (10Hz to 100MHz), DC (0
Active TV-Sync-Separator (pos. and neg.)

External: ≥0.3Vpp from DC to 60MHz
2nd triggering (Del. Trig.): normal with level

(peak to peak) <20Hz-100MHz (≤ 0.5div.)

line and external
HF (1.5kHz to100MHz), LF (0 to 1.5kHz)

control DC to 100 MHz

to

100MHz),

Horizontal Deflection

Time coefficients: 22 calibrated steps

from 0.5s/div. to 50ns/div. in 1-2-5 sequence
Accuracy in calibrated position: ±3%.
variable 2.5:1 up to 1.25s/div.,
with X-Mag. x10: 5ns/div. ±5%

Holdoff time: variable to approx. 10:1
Delay: 50ms - 100ns, variable 6:1 up to 300ms
Bandwidth X-amplifier: 0-3MHz (-3dB).

Input X-Amplifier via Channel II,
(sensitivity see Channel II specification)
X-Y phase shift: <3° below 120kHz.

Operation / Control

Auto Set (automatic parameter selection)
Manual (Front Panel switches)
Memory for 6 user-defined parameter settings
Remote control with built-in RS-232 interface

Component Tester

Test voltage: approx. 8.5V

Test current: approx. 7mA
Test frequency: approx. 50Hz
Test connection: 2 banana jacks 4mmØ
One test lead is grounded (Safety Earth)

(open circuit).

rms

(shorted).

rms

General Information

CRT: D14-372GH, rectangular screen (8x10div.)

internal graticule

Acceleration voltage: approx 14kV
Trace rotation: adjustable on front panel
Calibrator: square-wave generator (tr <4ns)
≈1kHz/1MHz; Output: 0.2V ±1% and 2V
Line voltage: 100-240V AC ±10%, 50/60Hz
Power consumption: approx. 40 Watt at 50Hz.

Min./Max. ambient temperature: -10°C...+40°C
Protective system: Safety class I (IEC1010-1)
Weight: approx. 5.6kg (12.4lbs), color:
Cabinet: W 285, H 125, D 380 mm
Lockable tilt handle

Subject to change without notice. 10/95

techno-brown

(11.1x4.9x14.8 inches)

60MHz Multi-Function Oscilloscope HM 604

-3

with Auto-Set, Save and Recall (6 Setup Memories)
Remote control via built-in RS-232 Interface

Vertical: 2 Channels, 1 mV/div. - 20 V/div., Comp.-Tester, 1MHz Calibrator
Time Base: 0.5 s/div. to 5 ns/div.; Trigger-after-delay; Alternate Trigger
Triggering: DC to 100 MHz; Automatic Peak to Peak; TV-Sync-Separator

The HM604-3 is HAMEG‘s 60 MHz microprocessor controlled analog oscil-
loscope. The internal microprocessor has the capability of automatically
configuring the oscilloscope parameters, when used in the "Auto Set"
mode, so as to present a display of three cycles of the input signal, with all
of the proper control settings automatically configured: a single trace will
be displayed with 4 to 6 divisions amplitude, while each signal will be 3 to 4
divisions high in dual trace mode. At a touch of the controls, the user can
over-ride the automatic settings. Manual control is simple with easy to see
indicators denoting uncalibrated operation by blinking. Switch/parameter
settings are easily visible as bright LED scale value indications.
One powerful feature is the ability to store user-defined test scenarios, that
can be called up on demand for repeated measurement tasks. A total of
6 setups can be saved and recalled as many times as required. Additional
setup information is possible via the RS-232 port, which can be controlled
from the serial port of a PC.
Although the instrument‘s vertical bandwidth is specified as 60 MHz, signals
to 100 MHz can be displayed and triggered. Signal expansion up to a factor
of 1,000 times can be obtained in the "Delay" and "Trigger after Delay"
modes. A switching mode power supply minimises power and results in a
lightweight unit weighing only 12.4 pounds (5.6kg).
The scope is ideal for fast troubleshooting. The Auto Set feature permits the
rapid inspection of test points, without the need to constantly adjust the
scope for each new test mode. The ability to Save/Recall facilitates the use
of this unit for final inspections, where multiple, repeated scope settings are
required. These capabilities result in labor saving operations which translate
to more efficiency and cost savings to the customer.

Accessories supplied: Line Cord, Operators Manual, 2 Probes 10:1

4

Subject to change without notice

General Information

This oscilloscope is easy to operate. The logical arrangement
of the controls allows anyone to quickly become familiar with
the operation of the instrument, 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.

Symbols

ATTENTION - refer to manual
Danger - High voltage

contains important information and warnings which have to
be followed by the user to ensure safe operation and to retain
the oscilloscope in a 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 Class 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.

The mains/line plug should be inserted before
connections are made to measuring circuits.

Protective ground (earth) terminal

Use of tilt handle

To view the screen from the best angle, there are three dif­ferent positions (C, D, E) for setting up the instrument. If the
instrument is set down on the floor after being carried, the
handle automatically remains in the upright carrying position
(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 (10° inclination), the handle
should be turned to the opposite direction of the carrying
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 carrying
by turning it to the upper side to lock in the B position. At the
same time, the instrument must be lifted, because otherwise
the handle will jump back.

The grounded accessible metal parts (case, sockets, jacks)
and the mains/line supply contacts (line/live, neutral) of the
instrument have been tested against insulation breakdown
with 2200V DC.

Under certain conditions, 50Hz 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
device being investigated.

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

equivalent rate falls far below the maximum permissible
value of 36pA/kg (0.5mR/h).

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 likely to be
impaired if, for example, the instrument

• shows visible damage,

• fails to perform the intended measurements,

• has been subjected to prolonged storage under
unfavourable conditions (e.g. in the open or in moist
environments),

Safety

This instrument has been designed and tested in accordance
with IEC Publication 1010-1 (overvoltage category II, pollution
degree 2), Safety requirements for electrical equipment for
measurement, control, and laboratory use. The CENELEC
regulations EN 61010-1 correspond to this standard. It has
left the factory in a safe condition. This instruction manual

Subject to change without notice

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

Operating conditions

The instrument has been designed for indoor use. The
permissible ambient temperature range during operation is
+10°C (+50°F) ... +40°C (+104°F). It may occasionally be
subjected to temperatures between +10°C (+50°F) and ­10°C (+14°F) without degrading its safety. The permissible
ambient temperature range for storage or transportation is

-40°C (-40°F) ... +70°C (+158°F).

The maximum operating altitude is up to 2200m (non­operating 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
environments. The oscilloscope can be operated in any
position, but the convection cooling must not be impaired.
The ventilation holes may not be covered. For continuous

5

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 30minutes at an
ambient temperature between +15°C (+59°F) and +30°C
(+86°F). Values without tolerances are typical for an
average instrument.

removed with a moistened cloth (99% water +1% 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.

Protective Switch-Off

EMC

This instrument conforms to the European standards
regarding the electromagnetic compatibility. The applied
standards are: Generic immunity standard EN50082-2:1995
(for industrial environment) Generic emission standard
EN50081-1:1992 ( for residential, commercial und light
industry environment).
This means that the instrument has been tested to the highest
standards.
Please note that under the influence of strong
electromagnetic fields, such signals may be superimposed
on the measured signals. Under certain conditions this is
unavoidable due to the instrument‘s high input sensitivity,
high input impedance and bandwidth. Shielded measuring
cables, shielding and earthing of the device under test may
reduce or eliminate those effect‘s.

Warranty

HAMEG warrants to its Customers that the products it
manufactures and sells will be free from defects in materials
and workmaship for a period of 2 years. This warranty shall
not apply to any defect, failure or damage caused by improper
use or inadequate maintenance and care. HAMEG shall not
obliged to provide service under this warranty to repair
damage resulting from attempts by personnel other than
HAMEG represantatives to install, repair, service or modify
these products.
In order to obtain service under this warranty, Customers
must contact and notify the distributor who has sold the
product.
Each instrument is subjected to a quality test with 10 hour
burn-in before leaving the production. Practically all early
failures are detected by this method. In the case of shipments
by post, rail or carrier it is recommended 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.

This instrument is equipped with a switch mode power supply.
It has both overvoltage and overload protection, which will
cause the switch mode supply to limit power consumption
to a minimum.
In this case a ticking noise may be heard.

Power supply

The oscilloscope operates on mains/line voltages between
100VAC and 240VAC. No means of switching to different
input voltages has therefore been provided.

The power input fuses are externally accessible. The
fuseholder is located above the 3-pole power connector.
The power input fuses are externally accessible, if the rubber
conector is removed. The fuseholder can be released by
pressing its plastic retainers with the aid of a small
screwdriver. The retainers are located on the right and left
side of the holder and must be pressed towards the center.
The fuse(s) can then be replaced and pressed in until locked
on both sides.

Use of patched fuses or short-circuiting of the fuseholder is
not permissible; HAMEG assumes no liability whatsoever for
any damage caused as a result, and all warranty claims
become null and void.

Fuse type:
Size 5x20mm; 0.8A, 250V AC fuse;
must meet IEC specification 127,
Sheet III (or DIN 41 662
or DIN 41 571, sheet 3).
Time characteristic: time-lag (T).

Attention!
There is a fuse located inside the instrument within
the switch mode power supply:

Size 5x20mm; 0.5A, 250V AC fuse;
must meet IEC specification 127,
Sheet III (or DIN 41 662
or DIN 41 571, sheet 3).
Time characteristic: fast (F).

This fuse must not be replaced by the operator!

Maintenance

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 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

6

Subject to change without notice

Type of signal voltage

With the HM604-3, most repetitive signals in the frequency
range up to at least 60MHz (-3dB) can be examined.

Sinewave signals of 100MHz are displayed with a height of
approx. 50% (-6dB). However when examining square or
pulse type waveforms, attention must be paid to the harmonic
content of such signals. The repetition frequency (fundamen­tal frequency) of the signal must therefore be significantly
smaller than the upper limit frequency of the vertical amplifier.

Displaying composite signals can be difficult, especially if they
contain no repetitive higher amplitude content which can be
used for triggering. This is the case with bursts, for instance.
To obtain a well-triggered display in this case, the assistance
of the variable holdoff and/or delay function may be required.
Television video signals are relatively easy to trigger using
the built-in TV-Sync-Separator (TV).

For optional operation as a DC or AC voltage amplifier, the
vertical amplifier input is provided with a DC/AC switch. The
DC position should only be used with a series-connected
attenuator probe or at very low frequencies or if the
measurement of the DC voltage content of the signal is
absolutely necessary.

The minimum signal voltage which must be applied to the Y
input for a trace of 1div. height is 1mVpp when the 1mV LED
is lit and the vernier is set to CAL by turning the fine
adjustment knob within the VOLTS/DIV. section fully
clockwise. However, smaller signals than this may also be
displayed. The deflection coefficients on the input attenuators
are indicated in mV/div. or V/div. (peak-to-peak value).
The magnitude of the applied voltage is ascertained by
multiplying the selected deflection coefficient by the vertical
display height in div. If an attenuator probe x10 is used, a
further multiplication by a factor of 10 is required to ascertain
the correct voltage value.

For exact amplitude measurements, the variable control
( VAR. 2.5:1) must be set to its calibrated detent CAL
position. When turning the variable control ccw, the

deflection coefficient LED will start to blink and the sensitivity
will be reduced until a maximum factor of 2.5 is reached.
Therefore any intermediate value is possible within the 1-2-5
sequence.

With direct connection to the vertical input, signals
up to 400Vpp may be displayed (attenuator set to 20V/
div., variable control to left stop).

With the designations

When displaying very low frequency pulses, the flat tops may
be sloping with AC coupling of the vertical amplifier (AC limit
frequency approx. 1.6 Hz for 3dB). In this case, DC operation
is preferred, provided the signal voltage is not superimposed
on a too high DC level. Otherwise a capacitor of adequate
capacitance must be connected to the input of the vertical
amplifier with DC coupling. This capacitor must have a
sufficiently high breakdown voltage rating. DC coupling is
also recommended for the display of logic and pulse signals,
especially if the pulse duty factor changes constantly.
Otherwise the display will move upwards or downwards at
each change. Pure direct voltages can only be measured with
DC-coupling.

Amplitude Measurements

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-peak
voltage (Vpp) value is applied. The latter corresponds to the
real potential difference between the most positive and most
negative points of a signal waveform.

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 = 2.83.
Conversely, it should be observed that sinusoidal voltages
indicated in Vrms (Veff) have 2.83 times the potential
difference in Vpp. The relationship between the different
voltage magnitudes can be seen from the following figure.

H = display height in div.,
U= signal voltage in Vpp at the vertical input,
D = deflection coefficient in V/div. at attenuator switch,

the required value can be calculated from the two given
quantities:

⋅

However, these three values are not freely selectable. They
have to be within the following limits (trigger threshold,
accuracy of reading):

H between 0.5 and 8div., if possible 3.2 to 8div.,
U between 1mVpp and 160Vpp,
D between 1mV/div. and 20V/div. in 1-2-5 sequence.

Examples:

Set deflection coefficient D = 50mV/div. 0.05V/div.,
observed display height H = 4.6div.,
required voltage U = 0.05x4.6 = 0.23Vpp.

Input voltage U = 5Vpp,
set deflection coefficient D = 1V/div.,
required display height H = 5:1 = 5div.

Signal voltage U = 230Vrmsx2√2 = 651Vpp
(voltage > 160Vpp, with probe 10:1: U = 65.1Vpp),
desired display height H = min. 3.2div., max. 8div.,
max. deflection coefficient D = 65.1:3.2 = 20.3V/div.,
min. deflection coefficient D = 65.1:8 = 8.1V/div.,
adjusted deflection coefficient D = 10V/div.

Voltage values of a sine curve

Vrms = effective value; Vp = simple peak or crest value;
Vpp = peak-to-peak value; Vmom = momentary value.

Subject to change without notice

The input voltage must not exceed 400V, independent
from the polarity.

If an AC voltage which is superimposed on a DC voltage is
applied, the maximum peak value of both voltages must not
exceed + or -400V. So for AC voltages with a mean value of
zero volt the maximum peak to peak value is 800Vpp.

If attenuator probes with higher limits are used, the
probes limits are valid only if the oscilloscope is set to

7

DC input coupling. If DC voltages are applied under AC input

coupling conditions the oscilloscope maximum input voltage
value remains 400V. The attenuator consists of a resistor in
the probe and the 1MΩ input resistor of the oscilloscope,
which are disabled by the AC input coupling capacity when
AC coupling is selected. This also applies to DC voltages with
superimposed AC voltages. It also must be noted that due
to the capacitive resistance of the AC input coupling capacitor,
the attenuation ratio depends on the signal frequency. For
sinewave signals with frequencies higher than 40Hz this
influence is negligible.

In the GD (ground coupling) setting, the signal path is
interrupted directly beyond the input. This causes the
attenuator to be disabled again, but now for both DC and AC
voltages.

With the above listed exceptions HAMEG 10:1 probes can
be used for DC measurements up to 600V or AC voltages
(with a mean value of zero volt) of 1200Vpp. The 100:1 pro­be HZ53 allows for 1200V DC or 2400Vpp for AC.

It should be noted that its ACpeak value is derated at higher
frequencies. If a normal x10 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 oscilloscope, a normal x10 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.

Total value of input voltage

The duration of a signal period or a part of it is
determined by multiplying the relevant time (horizon­tal distance in div.) by the time coefficient indicated
on the TIME/DIV. LED scales.

The variable time control (identified with an arrow
knob cap) must be in its calibrated position CAL. (arrow
pointing horizontally to the right). For exact time
measurements, the variable control ( VAR. 2.5:1) must
be set to its calibrated detent CAL position. When
turning the variable control ccw, the time coefficient
indicator LED starts blinking and the timebase speed
will be reduced until a maximum factor of 2.5 is
reached. Therefore any intermediate value is possible
within the 1-2-5 sequence.

With the designations

L = displayed wave length in div. of one period,
T = time in seconds for one period,
F = recurrence frequency in Hz of the signal,
Tc = time coefficient in s/div. on timebase switch and

the relation F = 1/T, the following equations can be stated:

= ⋅

=

=

=

⋅

⋅

=

=

⋅

With active X-MAG (x10) indicated by the x10 LED lit, the Tc
value must be divided by 10.

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

The dotted line shows a voltage alternating at zero volt level.
If superimposed on a DC voltage, the addition of the positive
peak and the DC voltage results in the max. voltage (DC +
ACpeak).

With Y-POS. control (input coupling to GD) it is possible to
use a horizontal graticule line as reference line for ground
potential before the measurement. It can lie below or above
the horizontal central line according to whether positive and/
or negative deviations from the ground potential are to be
measured.

Time Measurements

As a rule, most signals to be displayed are periodically
repeating processes, also called periods. The number of
periods per second is the repetition frequency. Depending
on the time base setting indicated by one of the TIME/DIV.
LED‘s, one or several signal periods or only a part of a period
can be displayed. The time coefficients are stated in s/div.
when the red sec-LED and the 0.5 or 0.2 LED (ms/div scale)
are lit. The ms/div. or µs/div. time coefficients are indicated
by one of the LED‘s on the ms or µs scale.

L between 0.2 and 10div., if possible 4 to 10div.,
T between 0.01µs and 5s,
F between 0.5Hz and 35MHz,
Tc between 0.05µs/div. and 0.5s/div. in 1-2-5 sequence

(with X-MAG. (x10) inactive), and

Tc between 5ns/div. and 20ms/div. in 1-2-5 sequence

(with X-MAG. (x10) active).

Examples:

Displayed wavelength L = 7div.,
set time coefficient Tc = 0.1µs/div.,
required period T = 7x0.1x10
required rec. freq. F = 1:(0.7x10

-6

= 0.7µs

-6

) = 1.428MHz.

Signal period T = 1s,
set time coefficient Tc = 0.2s/div.,
required wavelength L = 1:0.2 = 5div..

Displayed ripple wavelength L = 1div.,
set time coefficient Tc = 10ms/div.,
required ripple freq. F = 1:(1x10x10

-3

) = 100Hz.

TV-line frequency F = 15625Hz,
set time coefficient Tc = 10µs/div.,
required wavelength L = 1:(15 625x10-5) = 6.4div..

Sine wavelength L = min. 4div., max. 10div.,
Frequency F = 1kHz,
max. time coefficient Tc = 1:(4x10

3

) = 0.25ms/div.,
min. time coefficient Tc = 1:(10x103) = 0.1ms/div.,
set time coefficient Tc = 0.2ms/div.,
required wavelength L = 1:(10

3

x0.2x10-3) = 5div.

8

Subject to change without notice

Displayed wavelength L = 0.8div.,
set time coefficient Tc = 0.5µs/div.,
pressed X-MAG. (x10) button: Tc = 0.05µs/div.,
required rec. freq. F = 1:(0.8x0.05x10
required period T = 1:(25x10

6

) = 40ns.

-6

) = 25MHz,

If the time is relatively short as compared with the complete
signal period, an expanded time scale should always be
applied (X-MAG. (x10) active). In this case, the ascertained
time values have to be divided by 10. The time interval of
interest can be shifted to the screen center using the X-POS.
control.

When investigating pulse or square waveforms, the critical
feature is the risetime of the voltage step. To ensure that
transients, ramp-offs, and bandwidth limits do not unduly
influence the measuring accuracy, the risetime is generally
measured between 10% and 90% of the vertical pulse height.
For measurement, adjust the Y deflection coefficient with
its variable control together with the Y-POS. control so that
the pulse height is precisely aligned with the 0% and 100%
lines of the internal graticule. The 10% and 90% points of
the signal will now coincide with the 10% and 90% graticule
lines. The risetime is given by the product of the horizontal
distance in div. between these two coincident points and the
time coefficient setting. If X x10 magnification is used, this
product must be divided by 10. The fall time of a pulse can
also be measured by using this method.

The following figure shows correct positioning of the
oscilloscope trace for accurate risetime measurement.

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

.

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

particularly simple in this way. In principle it is possible to
measure in any display position and at any signal amplitude.
It is only important that the full height of the signal edge of
interest is visible in its full length at not too great steepness
and that the horizontal distance at 10% and 90% of the
amplitude is measured. If the edge shows rounding or
overshooting, the 100% should not be related to the peak
values but to the mean pulse heights. Breaks or peaks
(glitches) next to the edge are also not taken into account.
With very severe transient distortions, the rise and fall time
measurement has little meaning. For amplifiers with
approximately constant group delay (therefore good pulse
transmission performance) the following numerical
relationship between rise time tr (in ns) and bandwidth B

(in MHz) applies:

Connection of Test Signal

Caution: When connecting unknown signals to the
oscilloscope input, always use automatic triggering
and set the DC-AC input coupling switch to AC (DC
not lit). The attenuator should initially be set to 20V/
div.

Sometimes the trace will disappear after an input signal has
been applied. The attenuator must be switched to a higher
deflection coefficient by pressing the left (<) arrow pushbutton
in the VOLTS/DIV. section constantly or step by step, until
the vertical signal height is only 3-8div. With a signal amplitude
greater than 160Vpp, an attenuator probe must be inserted
before the vertical input. If, after applying the signal, the trace
is nearly blanked, the period of the signal is probably
substantially longer than the set value on the TIME/DIV. scale.
It should be switched to an adequately larger time coefficient
by pressing the left (<) arrow pushbutton in the TIME/DIV
section by pressing it constantly or step by step. In most
cases the easiest way to adapt the instruments settings to
the input signal is to depress the AUTO SET pushbutton for
automatic instrument settings.

With a time coefficient of 0.05µs/div. and X x10 magnification,
the example shown in the above figure results in a total
measured risetime of

= 1.6div x 0.05µs/div. : 10 = 8ns

t

tot

When very fast risetimes are being measured, the risetimes
of the oscilloscope amplifier and of the attenuator probe has
to be deducted from the measured time value. The risetime
of the signal can be calculated using the following formula.

=√

In this t
of the oscilloscope amplifier (approx. 12ns), and t
of the probe (e.g. = 2ns). If t
can be taken as the risetime of the pulse, and calculation is

is the total measured risetime, t

tot

is greater than 100ns, then t

tot

unnecessary.
Calculation of the example in the figure above results in a

signal risetime

is the risetime

osc

the risetime

p

=√ − =

The measurement of the rise or fall time is not limited to the
trace dimensions shown in the above diagram. It is only

The signal to be displayed can be connected directly to the Y ­input of the oscilloscope with a shielded test cable such as
HZ32 or HZ34, or reduced through a x10 or x100 attenuator
probe. The use of test cables with high impedance circuits is
only recommended for relatively low frequencies (up to
approx. 50kHz). For higher frequencies, the signal source
must be of low impedance, i.e. matched to the characteristic
resistance of the cable (as a rule 50Ω). Especially when
transmitting square and pulse signals, a resistor equal to the
characteristic impedance of the cable must also be connected
across the cable directly at the Y-input of the oscilloscope.
When using a 50Ω cable such as the HZ34, a 50Ω through
termination type HZ22 is available from HAMEG. When
transmitting square signals with short rise times, transient
phenomena on the edges and top of the signal may become
visible if the correct termination is not used. A terminating
resistance is sometimes recommended with sine signals as
well. Certain amplifiers, generators or their attenuators

tot

maintain the nominal output voltage independent of frequency
only if their connection cable is terminated with the prescribed
resistance. Here it must be noted that the terminating resistor
HZ22 will only dissipate a maximum of 2Watts. This power
is reached with 10Vrms or at 28.3Vpp with sine signal.

If a x10 or x100 attenuator probe is used, no termination is
necessary. In this case, the connecting cable is matched
directly to the high impedance input of the oscilloscope. When
using attenuators probes, even high internal impedance

Subject to change without notice

9

sources are only slightly loaded (approx. 10MΩ II 16pF or
100MΩ II 9pF with HZ53). Therefore, if the voltage loss due
to the attenuation of the probe can be compensated by a higher
amplitude setting, the probe should always be used. The series
impedance of the probe provides a certain amount of protection
for the input of the vertical amplifier. Because of their separa­te manufacture, all attenuator probes are only partially
compensated, therefore accurate compensation must be
performed on the oscilloscope (see Probe compensation ).

Standard attenuator probes on the oscilloscope normally
reduce its bandwidth and increase the rise time. In all cases
where the oscilloscope bandwidth must be fully utilized (e.g.
for pulses with steep edges) we strongly advise using the
probes HZ51 (x10) HZ52 (x10 HF) and HZ54 (x1 and x10).
This can save the purchase of an oscilloscope with larger
bandwidth.

The probes mentioned have a HF-calibration in addition to
low frequency calibration adjustment. Thus a group delay
correction to the upper limit frequency of the oscilloscope is
possible with the aid of an 1MHz calibrator, e.g. HZ60.

where a trace appears on the screen if the INTENS. knob is
in center position, all LED‘s should remain unlit. The trace,
displaying one baseline or the shorter COMP TESTER
baseline, should be visible after a short warm-up period of
approx. 10 seconds. If the COMP TESTER mode is active,
depress the COMP TESTER pushbutton once to switch to
XY or Yt mode. In XY mode the XY LED in the TIME/DIV
section is lit, in this case depress the XY pushbutton once to
switch over to Yt mode. Adjust Y-POS.I and X-POS. controls
to center the baseline. Adjust INTENS. (intensity) and FOCUS
controls for medium brightness and optimum sharpness of
the trace. The oscilloscope is now ready for use.

• Rotate the variable controls with arrows, i.e. TIME/DIV.
variable control, CH.I and CH.II attenuator variable
controls, and HOLD OFF control to their calibrated detent.

• Set all controls with marker lines to their midrange position
(marker lines pointing vertically).

••

• Depress the upper NORM. pushbutton until the AC

••
symbol on the trigger coupling scale is lit.

• Both GD input coupling pushbutton switches for CH.I and
CH.II in the Y-field should be set to the GD position (GD lit).

In fact the bandwidth and rise time of the oscilloscope are
not noticably changed with these probe types and the
waveform reproduction fidelity can even be improved because
the probe can be matched to the oscilloscopes individual pulse
response.

If a x10 or x100 attenuator probe is used, DC input
coupling must always be used at voltages above 400V .
With AC coupling of low frequency signals, the
attenuation is no longer independent of frequency,
pulses can show pulse tilts. Direct voltages are
suppressed but load the oscilloscope input coupling
capacitor concerned. Its voltage rating is max. 400 V
(DC + peak AC). DC input coupling is therefore of quite
special importance with a x100 attenuation probe
which usually has a voltage rating of max. 1200 V (DC
+ peak AC). A capacitor of corresponding capacitance
and voltage rating may be connected in series with
the attenuator probe input for blocking DC voltage (e.g.
for hum voltage measurement).

With all attenuator probes, the maximum AC input voltage
must be derated with frequency usually above 20kHz.
Therefore the derating curve of the attenuator probe type
concerned must be taken into account.

The selection of the ground point on the test object is
important when displaying small signal voltages. It should
always be as close as possible to the measuring point. If this
is not done, serious signal distortion may result from spurious
currents through the ground leads or chassis parts. The
ground leads on attenuator probes are also particularly critical.
They should be as short and thick as possible. When the
attenuator probe is connected to a BNC-socket, a BNC­adapter, should be used. In this way ground and matching
problems are eliminated. Hum or interference appearing in
the measuring circuit (especially when a small deflection
coefficient is used) is possibly caused by multiple grounding
because equalizing currents can flow in the shielding of the
test cables (voltage drop between the protective conductor
connections, caused by external equipment connected to the
mains/line, e.g. signal generators with interference protection
capacitors).

If only a spot appears (CAUTION! CRT phosphor can be
damaged), reduce the intensity immediately and check that
the XY mode is not selected (XY LED dark). If the trace is
not visible, check the correct positions of all knobs and modes
(particularly NM LED - normal triggering - LED on).

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.

The instrument is so designed that even incorrect operation
will not cause serious damage.

The HM604-3 accepts all signals from DC (direct voltage) up
to a frequency of at least 60MHz (-3dB). For sinewave
voltages the upper frequency limit will be 100MHz (-6dB).
However, in this higher frequency range the vertical display
height on the screen is limited to approx. 4-5div. The time
resolution poses no problem. For example, with 100MHz and
the fastest adjustable sweep rate (5ns/div.), one cycle will
be displayed every 2div. The tolerance on indicated values
amounts to ±3% in both deflection directions. All values to
be measured can therefore be determined relatively
accurately.

However, from approximately 10MHz upwards the measuring
error will increase as a result of loss of gain. At 18MHz this
reduction is about 10%. Thus, approximately 11% should be
added to the measured voltage at this frequency. As the
bandwidth of the amplifiers may differ slightly (normally
between 60 and 78MHz), the measured values in the upper
frequency range cannot be defined exactly. Additionally, as
already mentioned, for frequencies above 60MHz the 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.

First Time Operation

Switch on the oscilloscope by depressing the red POWER
pushbutton. The instrument will revert to its last used
operating mode. Except in the case of COMP. TESTER mode,

10

Trace Rotation TR

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

Subject to change without notice

of the oscilloscope on the place of work. A centred trace
may not align exactly with the horizontal center line of the
graticule. A few degrees of misalignment can be corrected
by a potentiometer accessible through an opening on the
front panel marked TR.

Probe compensation and use

trimmer can be found in the probe information sheet. Adjust
the trimmer with the insulated screw driver provided, until
the tops of the square wave signal are exactly parallel to the
horizontal graticule lines (see 1kHz diagram). The signal height
should then be 4div. ± 0.16div. (= 4 % (oscilloscope 3% and
probe 1%). During this adjustment, the signal edges will
remain invisible.

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

For this purpose a square wave signal with a very fast rise
time and minimum overshoot should be used, as the
sinusoidal contents cover a wide frequency range. The
frequency accuracy and the pulse duty factor are not of such
importance.

The built-in calibration generator provides a square wave signal
with a very fast risetime (<4ns), and switch-selectable
frequencies of approx. 1kHz and 1MHz from two output
sockets below the CRT screen.

As the squarewave signals are used for probe compensation
adjustments, neither the frequency accuracy nor the pulse
duty factor are of importance and therefore not specified.
One output provides 0.2Vpp ±1% (tr <4ns) for 10:1 probes,
and the other 2Vpp for 100:1 probes. When the Y deflection
coefficients are set to 5mV/div., these calibration voltages
correspond to a screen amplitude of 4div.

The output sockets have an internal diameter of 4.9mm to
accommodate the internationally accepted shielding tube
diameter of modern Probes and F-series slimline probes. Only
this type of construction ensures the extremly short ground
connections which are essential for an undistorted waveform
reproduction of non-sinusoidal high frequency signals.

Adjustment at 1kHz

The C-trimmer adjustment (low frequency) compensates the
capacitive loading on the oscilloscope input (approx. 20pF
for the HM604-3). By this adjustment, the capacitive division
assumes the same ratio as the ohmic voltage divider to ensure
the same division ratio for high and low frequencies, as for
DC. (For 1:1 probes or switchable probes set to 1:1, this
adjustment is neither required nor possible). A baseline par­allel to the horizontal graticule lines is essential for accurate
probe adjustments. (See also

Connect the probes (Types HZ51, 52, 53, 54, or HZ36) to the
CH.I input. One deflection coefficient in the VOLTS/DIV
section of channel I must lit. If this is not the case depress
the CHI pushbutton once and switch off channel II by
depressing the CHII pushbutton once. Set input coupling CH
I to DC (LED illuminates) and check that GD is switched off.
The CHI deflection coefficient must be 5mV/div., and TIME/

DIV. should be set to 0.2ms/div., and all variable controls to
CAL. position. Plug the the probe tip into the appropriate

calibrator output socket, i.e. 10:1 probes into the 0.2V socket,
100:1 probes into the 2V socket.

incorrect correct incorrect

Approximately 2 complete waveform periods are displayed
on the CRT screen. The compensation trimmer should be
adjusted. The location of the low frequency compensation

„Trace rotation TR“

).

Adjustment at 1MHz

Probes HZ51, 52 and 54 can also be HF-compensated. They
incorporate resonance de-emphasing networks (R-trimmer
in conjunction with inductances and capacitors) which per­mit probe compensation in the range of the upper frequency
limit of the vertical oscilloscope 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 leading 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
HM604-3 can be utilized without risk of unwanted waveform
distortion.

Prerequisite for this HF compensation is a square wave
generator with fast risetime (typically 4ns), and low output
impedance (approx. 50Ω), providing 0.2V and 2V at a
frequency of approx. 1MHz. The calibrator output of the
HM604-3 meets these requirements when the CAL.
pushbutton is depressed.

Connect the probe to CH.I input. Depress the CAL.
pushbutton for 1MHz. Operate the oscilloscope as described
under 1kHz but select for 0.2µs/div TIME/DIV. setting.

Insert the probe tip into the output socket marked 0.2V. A
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 rising
edge as well as the upper left corner of the pulse top. The
location of the high frequency compensation trimmer(s) can
also be found in the probe information sheet. These R­trimmer(s) have to be adjusted such that the beginning of
the pulse is as straight as possible. Overshoot or excessive
rounding are unacceptable. The adjustment is relatively easy
if only one adjusting point is present. In case of several
adjusting points the adjustment is slightly more difficult, but
causes a better result. The rising edge should be as steep as
possible, with a pulse top remaining as straight and horizon­tal as possible.

incorrect correct incorrect

After completion of the HF-adjustment, the signal amplitude
displayed on the CRT screen should have the same value as
during the 1kHz 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 HM604-3. Furthermore, the HF-adjustment feature
is nearly always missing so that waveform distortion can not
be entirely excluded.

Subject to change without notice

11

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

Prerequisites for precise and easy probe adjustments, as well
as checks of deflection coefficients, are straight horizontal
pulse tops, calibrated pulse amplitude, and zero-potential at
the pulse base. Frequency and duty cycle are relatively
uncritical. For interpretation of transient response, fast pulse
risetimes and low-impedance generator outputs are of
particular importance.

Providing these essential features, as well as switch­selectable output-frequencies, the calibrator of the HM604­3 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.-
outputs via a suitable probe.

The voltage provided at a high-impedance input (1MΩ II 15­30pF) will correspond to the division ratio of the probe used
(10:1 = 20mVpp, 100:1 = also 20mVpp from 2V output).
Suitable probes are HZ51, 52, 53, and 54.

Operating modes of the vertical
amplifiers in Yt mode.

The vertical amplifier is set to the desired operating mode by
using the 2 pushbuttons CH I and CH II (for CH I, CH II,
DUAL and ADD mode) in the Y field of the front panel. The
different modes are indicated by LED‘s in the channel I and
channel II VOLTS/DIV sections and the ADD LED in ADD
mode.
If only CH II is active to switch to CH I mode, first press the
CH I pushbutton to switch on channel I. Now the oscilloscope
is in DUAL mode where LED‘s in both VOLTS/DIV sectors
are lit. Then the CH II pushbutton must be depressed once
to switch off channel II. It is not possible to operate the
oscilloscope with both channels switched off. That is why
the required channel must first be switched on and then the
unwanted channel must be switched off.
To switch from CH I to CH II mode, first switch on CH II and
then switch off CH I. If internal triggering is selected (EXT
LED near the TRIG. INP. socket extinguished), the trigger
source indicator LED‘s (TR I and TR II) will be switched over
simultaneously.

DUAL mode is selected if a LED is lit in each VOLTS/DIV
sectors. As mentioned before, one channel is always present
and so the other channel must be switched on for DUAL
mode operation.
In DUAL mode both channels are working. Two signals can
be displayed together in alternate or chopped mode. The
alternate mode is not suitable for displaying very slow-running
processes. The display then flickers or appears to jump.
Therefore the instrument automatically switches over from
alternate to chopped mode if TIME/DIV settings from 0.5ms/
div to 0.5s/div are used. If in chopped DUAL mode, both
channels are switched over constantly at a high frequency
within a sweep period. Low frequency signals below 1kHz,
or with periods longer than 1ms are then displayed without
flicker. Conversely in DUAL alternate mode, the displayed
channel switches over from channell I to channel II and vice
versa after each sweep period.
In DUAL mode the internal trigger source can be switched
over from channel I to channel II and vice versa if the TRIG.
pushbutton is depressed for a short time. Depressing the
TRIG. pushbutton in DUAL mode for a longer time switches

over to alternate triggering and consequently both TR I and
TR II LED‘s are lit. As alternate triggering is not possible in
combination with DUAL chopped mode, the instrument
automatically switches over to the alternate mode if DUAL
chopped mode was active before. Alternate triggering can
be switched off by depressing the TRIG. pushbutton for a
short time. Then just one TR LED is lit.

DUAL chopped mode is also automatically switched off when
TV-F (television frame triggering) is selected to avoid
interference.
In combination with delay and triggered delay mode, DUAL
chopped mode can also be switched to DUAL alternate mode
by simultaniously depressing both pushbuttons marked with
< and > arrows in the TIME/DIV sector. Any change in the
delay mode time base setting reverts to the DUAL chopped
mode.

ADD mode is selected by simultaneously depressing both
CH I and CH II pushbuttons which causes the ADD LED
between both pushbuttons to light.
In ADD mode the signals of both channels are algebraically
added (±I ±II) and displayed as one signal. Whether the
resulting display shows the sum or difference is dependent
on the phase relationship or the polarity of the signals and on
the invert function indicated by the INV LED‘s for each
channel. To quit the ADD mode, depress the pushbutton for
the required channel or depress both CH I and CH II
pushbuttons for a short time to switch back to DUAL mode.
As alternate triggering is not available in ADD mode, the
instrument switches over from ADD mode to alternate DUAL
mode if the TRIG pushbutton is depressed for a longer time.

In ADD mode the following combinations are possible for
In-phase input voltages:

• Both INV (invert) function CH.I and
INV (invert) function CH.II active

• released or depressed = sum.

• Only one INV (invert) function active = difference.

Antiphase input voltages:

• Both INV (invert) function active
or inactive = difference.

• INV (invert) function CH.I or INV
(invert) function CH.II active = sum.

In the ADD mode the vertical display position is dependent
upon the Y-POS. setting of both channels. The same Y
deflection coefficient is normally used for both channels with
algebraic addition.

Please note that the Y-POS. settings are also added
but are not affected by the INV setting.

Differential measurement techniques allow direct
measurement of the voltage drop across floating components
(both ends above ground). Two identical probes should be
used for both vertical inputs. In order to avoid ground loops,
use a separate ground connection and do not use the probe
ground leads or cable shields.

X-Y Operation

For X-Y operation, the pushbutton in the X field marked XY
must be depressed. Then the XY LED in the TIME/DIV sector
is lit and the time coefficient indication is switched off. The X
signal is then derived from the INPUT CH II (X). The
calibration of the X signal during X-Y operation is determined
by the setting of the Channel II Y deflection coefficient and
variable control.
This means that the sensitivity ranges and input impedances

12

Subject to change without notice

are identical for both the X and Y axes. However , the Y-POS.II
control is disconnected in this mode. Its function is taken
over by the X-POS. control. It is important to note that the
X-MAG. (x10) facility, normally used for expanding the
sweep, is inoperative in the X-Y mode. It should also be noted
that the bandwidth of the X amplifier is ≤ 2.5MHz (-3dB), and
therefore an increase in phase difference between both axes
is noticeable from 50kHz upwards.

The inversion of the X-input signal using the INV CH.II button
is not possible.

Lissajous figures can be displayed in the X-Y mode for certain
measuring tasks:

• Comparing two signals of different frequency or bringing
one frequency up to the frequency of the other signal.
This also applies for whole number multiples or fractions
of the one signal frequency.

• Phase comparison between two signals of the same
frequency.

Phase comparison with Lissajous figures

The following diagrams show two sine signals of the same
frequency and amplitude with different phase angles.

Should both input voltages be missing or fail in the X­Y mode, a very bright light dot is displayed on the
screen. This dot can burn into the phosphor at a too
high brightness setting (INTENS. knob) which causes
either a lasting loss of brightness, or in the extreme
case, complete destruction of the phosphor at this
point.

Phase difference measurement
in DUAL mode

A larger phase difference between two input signals of the
same frequency and shape can be measured very simply on
the screen in Dual mode. The time base should be triggered
by the reference signal (phase position 0). The other signal
can then have a leading or lagging phase angle.

For greatest accuracy adjust slightly over one period and
approximately the same height of both signals on the screen.
The variable controls for amplitude and time base and the
TRIG. LEVEL knob can also be used for this adjustment
without influence on the result. Both base lines are set onto
the horizontal graticule center line with the Y-POS. knobs
before the measurement. With sinusoidal signals, observe
the zero (crossover point) transitions; the sine peaks are less
accurate. If a sine signal is noticeably distorted by even
harmonics, or if a DC voltage is present, AC coupling is
recommended for both channels. If it is a question of pulses
of the same shape, read off at steep edges.
It must be noted that the phase difference cannot be
determined if alternate triggering (TR I and TR II lit) is selected.

Calculation of the phase angle or the phase shift between
the X and Y input voltages (after measuring the distances a
and b on the screen) is quite simple with the following
formula, and a pocket calculator with trigonometric functions.
Apart from the reading accuracy, the signal height has no
influence on the result.

ϕ=

ϕ=√

ϕ=

The following must be noted here:

• Because of the periodic nature of the trigonometric
functions, the calculation should be limited to angles ≤90°
However here is the advantage of the method.

• Do not use a too high test frequency. The phase shift of
the two oscilloscope amplifiers of the HM604-3 in the X­Y mode can exceed an angle of 3° above 120kHz.

• It cannot be seen as a matter of course from the screen
display if the test voltage leads or lags the reference
voltage. A CR network before the test voltage input of
the oscilloscope can help here. The 1 MΩ input resistance
can equally serve as R here, so that only a suitable
capacitor C needs to be connected in series. If the
aperture width of the ellipse is increased (compared with
C short-circuited), then the test voltage leads the
reference voltage and vice versa. This applies only in the
region up to 90° phase shift. Therefore C should be
sufficiently large and produce only a relatively small just
observable phase shift.

Phase difference measurement in DUAL mode

t = horizontal spacing of the zero transitions in div.
T = horizontal spacing for one period in div.

In the example illustrated, t = 3div. and T = 10div. The phase
difference in degrees is calculated from

ϕ

ϕ π π

Relatively small phase angles at not too high frequencies can
be measured more accurately in the X-Y mode with Lissajous
figures.

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

Subject to change without notice

13

Ω Ω ω Ω ω

where

= unmodulated carrier amplitude

U

T

ΩΩ

Ω = 2πF = angular carrier frequency

ΩΩ
ωω

ω = 2πf = modulation angular frequency

ωω

m = modulation factor (i.a. œ 1 100%).

The lower side frequency F-f and the upper side frequency
F+f arise because of the modulation apart from the carrier
frequency F.

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

The display of the amplitude-modulated HF oscillation can be
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 (NM LED lit) button
depressed) using a suitable TRIG. LEVEL setting and possibly
also using the time variable adjustment.

Oscilloscope setting for a signal according to figure 2:

• Y: CH. I; 20mV/div.; AC.

• TIME/DIV.: 0.2ms/div.

• Triggering: Normal (NM LED lit); with LEVEL-setting;
internal (or external) triggering.

Figure 2
Amplitude modulated oscillaton: F = 1 MHz; f = 1 kHz;
m = 50 %; UT = 28.3 mVrms.

If the two values a and b are read from the screen, the
modulation factor is calculated from

where a = UT (1+m) and b = UT (1-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 time base

Time related amplitude changes on a measuring signal (AC
voltage) are displayable in Yt-mode. In this mode the signal
voltage deflects the beam in vertical direction while the

timebase generator moves the beam from the left to the
right of the screen (time deflection).

Normally there are periodically repeating waveforms to be
displayed. Therefore the time base must repeat the time
deflection periodically too. To produce a stationary display,
the time base must only be triggered if the signal height and
slope condition coincide with the former time base start
conditions. A DC voltage signal can not be triggered as it is a
constant signal with no slope.

Triggering can be performed by the measuring signal itself
(internal triggering) or by an external supplied but synchronous
voltage (external triggering).

The trigger voltage should have a certain minimum amplitude.
This value is called the trigger threshold. It is measured with
a sine signal. Except when external trigger is used the trigger
threshold can be stated as vertical display height in div.,
through which the time base generator starts, the display is
stable, and the trigger LED (located in the X field above the
trigger coupling scale) lights.

The internal trigger threshold of the HM604-3 is given as ≤
5div. When the trigger voltage is externally supplied, it can
be measured in Vpp at the TRIG. INP. socket. Normally, the
trigger threshold may be exceeded up to a maximum factor
of 20.

The HM604-3 has two trigger modes, which are characterized
in the following.

Automatic Peak-Triggering

The triggerring mode is indicated by the NM LED beside the
NORM pushbuttons on the X field of the front panel.

Automatic triggering is selected if the NM LED is unlit,
otherwise simultaneously depress both NORM pushbuttons
to select automatic triggering. Then the sweep generator
will be running without test signal or external trigger voltage.
A base line will always be displayed even with no signal.
With an applied AC signal the peak value triggering enables
the user to select the voltage point on the trigger signal, by
the adjustment of the TRIG. LEVEL control. The TRIG. LEVEL
control range depends on the peak to peak value of the signal.
This trigger mode is therefore called Automatic Peak (Value)­Triggering. Operation of the scope needs only correct
amplitude and timebase settings, for a constantly visible trace.
Automatic mode is recommended for all uncomplicated
measuring tasks. However, automatic triggering is also the
appropriate operation mode for the „entry“ into difficult
measuring problems, e.g. when the test signal is unknown
relating to amplitude, frequency or shape. Presetting of all
parameters is now possible with automatic triggering; the
change to normal triggering can follow thereafter . AUTO SET
therefore sets the instrument to automatic peak-triggering
mode in combination with AC trigger coupling.

The automatic triggering works above 20Hz. The failure of
automatic triggering at frequencies below 20Hz is abrupt.
However, it is not signified by the trigger indicator LED (above
TRIG.) this is still blinking. Break down of triggering is best
recognizable at the left screen edge (the start of the trace in
differing display height).

The automatic peak triggering operates over all variations or
fluctuations of the test signal above 20Hz. However, if the
pulse duty factor of a square-wave signal exceeds a ratio of
100:1, switching over to normal triggering will be necessary.
As the peak value detection makes no sense in combination
with DC signals, it is switched off automatically in DC trigger

14

Subject to change without notice

coupling mode. In this case the automatic is still present, but
a wrong TRIG. LEVEL setting causes an untriggered display.
Automatic triggering is practicable with internal and external
trigger voltage.

In alternate triggering mode (TR I and TR II lit) the peak value
detection is switched off.

Normal Triggering

With normal triggering (both NORM pushbuttons depressed
until the NM LED is lit) and TRIG. LEVEL adjustment, the
sweep can be started by AC signals within the frequency
range defined by the TRIG. coupling setting. In the absence
of an adequate trigger signal or when the trigger controls
(particularly the TRIG. LEVEL control) are misadjusted, no
trace is visible, i.e. the screen blanked completely.

When using the internal normal triggering mode, it is possible
to trigger at any amplitude point of a signal edge, even with
very complex signal shapes, by adjusting the TRIG. LEVEL
control. Its adjusting range is directly dependent on the display
height, which should be at least 0.5div. If it is smaller than
1div., the TRIG. LEVEL adjustment needs to be operated with
a sensitive touch. In the external normal triggering mode,
the same applies to approx. 0.3Vpp external trigger voltage
amplitude.
Other measures for triggering of very complex signals are
the use of the time base variable control and HOLDOFF time
control, hereinafter mentioned.

Slope

The time base generator can be triggered by a rising or falling
edge of the test signal. The ± pushbutton marking selects
the slope polarity. If the LED above the pushbutton is lit, the
( - ) falling edge is used for triggering. This is valid with
automatic and normal triggering. The positive (+) slope
direction (LED dark) means an edge going from a negative
potential and rising to a positive potential. This has nothing
to do with zero or ground potential and absolute voltage
values. The positive slope may also lie in a negative part of a
signal. A falling ( - ) edge will trigger the timebase when the
minus symbol is lit.

However the trigger point may be varied within certain limits
on the chosen edge using the LEVEL control. The slope
direction is always related to the input signal and the non
inverted display.

Trigger coupling

The coupling mode and accordingly the frequency range of
the trigger signal can be changed using the upper or lower
NORM pushbutton. The selected coupling mode is indicated
on the LED scale above.

AC:Trigger range <20Hz to 100MHz .

This is the most frequently used trigger mode. The trigger
threshold is increasing below 20Hz and above 100MHz.

The AUTO SET function always selects AC trigger
coupling.

DC: Trigger range DC to 100MHz.

DC triggering is recommended, if the signal is to be
triggered with quite slow processes or if pulse signals
with constantly changing pulse duty factors have to be
displayed.

With DC- or LF-trigger coupling, always work with nor­mal triggering (NM) and TRIG.LEVEL adjustment. If

automatic (peak-value) triggering was in use, the peak

value detection is then switched off automatically.

LF: Trigger range DC to 1.5kHz (low-pass filter).

The LF coupling is often more suited for low-frequency
signals than the DC coupling, because the (white) noise
in the trigger voltage is strongly suppressed. So jitter or
double-triggering of complex signals is avoidable or at
least reduced, in particular with very low input voltages.
The trigger threshold increases above 1.5kHz.

TV-L / TV-F: The built-in active TV-Sync-Separator provides

the separation of sync pulses from the video signal.Even
distorted video signals are triggered and displayed in a
stable manner.

Video signals are triggered in the automatic mode (NM LED
dark). The internal triggering is virtually independent of the
display height, but the sync pulse must exceed 0.5div. height.
TV-L is for line sync pulse separation and triggering, while
TV-F is for field sync pulse separation and triggering.
The slope of the leading edge of the synchronization pulse is
critical for the SLOPE selection. If the displayed sync pulses
are above the picture (field) contents (leading edge positive
going), then the positive going SLOPE (+) must be chosen.
In the case of sync pulses below the field/line, the leading
edge is negative and - (minus) symbol above the ± pushbutton
must lit. Since the INV (invert) function may cause a
misleading display, it must not be activated (INV LED dark).

On the 2ms/div setting and field TV triggering (TV-F) selected
1 field is visible if a 50 fields/s signal is applied. If the hold off
control is in fully ccw position, it triggers without line
interlacing affects caused by the consecutive field. More
details in the video signal become visible if in delayed trigger
mode the timebase speed is increased (see DELAY / AFTER
DELA Y TRIGGERING). The X-MAG. (x10) expansion may also
be used (x10 LED lit). The influence of the integrating network
which forms a trigger pulse from the vertical sync pulses
may become visible under certain conditions. Due to the
integrating network time constant not all vertical sync pulses
starting the trace are visible.

Disconnecting the trigger circuit (e.g. by double depressing
and releasing the EXT. button next to the TRIG. INP.
BNC socket in the Y field) can usually result in triggering the
consecutive (odd or even) field.
On the 10µs/div setting and line TV triggering (TV-L) selected,
approx. 1½ lines are visible. Those lines originate from the
odd and even fields at random.

The sync-separator-circuit also operates with external
triggering. It is important that the voltage range (0.3Vpp to
3Vpp) for external triggering should be noted. Again the
correct slope setting is critical, because the external trigger
signal may not have the same polarity or pulse edge as the
test signal displayed on the CRT. This can be checked, if the
external trigger voltage itself is displayed first (with internal
triggering).

In most cases, the composite video signal has a high DC
content. With constant video information (e.g. test pattern
or color bar generator), the DC content can be suppressed
easily by AC input coupling of the oscilloscope amplifier .With
a changing picture content (e.g. normal program), DC input
coupling is recommended, because the display varies its
vertical position on screen with AC input coupling at each
change of the picture content. The DC content can be
compensated using the Y-POS. control so that the signal
display lies in the graticule area. Then the composite video
signal should not exceed a vertical height of 6div.

Subject to change without notice

15

Line triggering (~)

A voltage originating from mains/line (50 to 60Hz) is used for
triggering purposes if the trigger coupling (TRIG.) is set to ~.
This trigger mode is independent of amplitude and frequency
of the Y signal and is recommended for all mains/line
synchronous signals. This also applies within certain limits,
to whole number multiples or fractions of the line frequency.
Line triggering can also be useful to display signals below
the trigger threshold (less than 0.5div). It is therefore
particularly suitable for measuring small ripple voltages of
mains/line rectifiers or stray magnetic field in a circuit. In this
trigger mode the ± (SLOPE) pushbutton selects the positive
or negative portion of the line sinewave. The TRIG. LEVEL
control can be used for trigger point adjustment.

Magnetic leakage (e.g. from a power transformer) can be
investigated for direction and amplitude using a search or
pick-up coil. The coil should be wound on a small former
with a maximum of turns of a thin lacquered wire and
connected to a BNC connector (for scope input) via a shielded
cable. Between cable and BNC center conductor a resistor
of at least 100Ω should be series-connected (RF decoupling).
Often it is advisable to shield statically the surface of the
coil. However, no shorted turns are permissible. Maximum,
minimum, and direction to the magnetic source are detectable
at the measuring point by turning and shifting the coil.

Alternate triggering

With alternate triggering (TR I and TR II LED´s lit) it is possible
to trigger two signals which are different in frequency
(asynchronous). In this case the oscilloscope must be
operated in DUAL alternate mode and internal triggering each
input signal must be of sufficient height to enable trigger. To
select for alternate triggering the TRIG. pushbutton must be
held depressed until both TR I and TR II LED‘s are illuminated.
To avoid trigger problems due to different DC voltage
components, AC input coupling for both channels is
recommended.

The internal trigger source is switched in alternate trigger
mode in the same way as the channel switching system in
DUAL alternate mode, i.e. after each time base sweep. If a
timebase range (TIME/DIV) is chosen where the chopper
generator is automatically activated, switching to alternate
trigger will automatically switch off the chopper generator,
and activate DUAL alternate mode. This measure is required
as the chopper generator chops randomly without
synchronization to the time base. Phase difference
measurement is not possible in this trigger mode as the
trigger level and slope setting are equal for both signals. Even
with 180° phase difference between both signals, they appear
with the same slope direction.

External triggering

When in internal trigger mode the EXT LED in the Y field is
dark. Depressing the pushbutton below the EXT indicator
switches the EXT LED on. Now the internal triggering is
disconnected and the timebase can be triggered externally
via the TRIG. INP. socket using a 0.3Vpp to 3Vpp voltage,
which is in synchronism with the test signal.
This trigger voltage may have a completely different form
from the test signal voltage. Triggering is even possible in
certain limits with whole number multiples or fractions of
the test frequency, but only with synchronous signals.

The input impedance of the TRIG. INP. socket is approx.
100kΩ II 10pF.

The maximum input voltage of the input circuit is 100V
(DC+peak AC).

It must be noted that a different phase angle between the
measuring and the triggering signal may cause a display not
coinciding with the slope pushbutton setting.
The trigger coupling selection can also be used in external
triggering mode.

Trigger indicator

An LED on condition (above the TRIG. symbol) indicates that
the trigger signal has a sufficient amplitude and the TRIG.
LEVEL control setting is correct. This is valid with automatic
and with normal triggering. By observing the trigger LED,
sensitive TRIG. LEVEL adjustment is possible when normal
triggering is used, particularly at very low signal frequencies.
The indication pulses are of only 100ms duration.

Thus for fast signals the LED appears to glow continuously,
for low repetition rate signals, the LED flashes at the repetition
rate or at a display of several signal periods not only at the
start of the sweep at the left screen edge, but also at each
signal period.

In automatic triggering mode the sweep generator starts
repeatedly without test signal or external trigger voltage. If
the trigger signal frequency is <20Hz the sweep generator
starts without awaiting the trigger pulse. This causes an
untriggered display and a flashing trigger LED.

Holdoff-time adjustment

If it is found that a trigger point cannot be found on extremely
complex signals, even after careful adjustment of the TRIG.
LEVEL control, a stable display may often be obtained using
the HOLD OFF control (in the X-field). This facility varies the
holdoff time between two sweep periods approx. up to the
ratio 10:1. 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 delayed until
the optimum or required time. Another way to trigger such
signals, is to operate the instrument in DELAY mode. The
function of this control is again to delay the sweep start but
the delay time is then visible on the screen as the delay
position (DEL. POS.). See DELAY/After DELAY Triggering.

A very noisy signal or a signal with a higher interfering
frequency is at times displayed double. It is possible
that LEVEL adjustment only controls the mutual phase
shift, but not the double display. The stable single
display of the signal, required for evaluation, is easily
obtainable by expanding the hold off time. T o this end
the HOLD OFF knob is slowly turned to the right, until
one signal is displayed.

A double display is possible with certain pulse signals, where
the pulses alternately show a small difference of the peak
amplitudes. Only a very exact TRIG. LEVEL adjustment
makes a single display possible. The use of the HOLD OFF
knob simplifies the right adjustment.

After specific use the HOLD OFF control should be reset
into its calibration detent (fully ccw), otherwise the brightness
of the display is reduced drastically. The function is shown in
the following figures.

16

Subject to change without notice

Fig. 1 shows a case where the HOLD OFF knob is in the
minimum position (x1) and various different waveforms are
overlapped on the screen, making the signal observation
unsuccessful.
Fig. 2 shows a case where only the desired parts of the signal
are stably displayed.

Delay / After Delay Triggering

As mentioned before, triggering starts the time base sweep
and unblanks the beam. After the maximum X deflection to
the right, the beam is blanked and flies back to the (left) start
position. After the hold off period the sweep is started
automatically by the automatic trigger or the next trigger
signal. In normal triggering mode the automatic trigger is
switched off and will only start on receipt of a trigger signal.

Photo 1 (composite video signal)

MODE: undelayed
TIME/DIV: 5ms/div
Trigger coupling: TV-F
Trigger slope: falling ( - )

Depressing the DELAY pushbutton once for a short time,
lights the SEA (SEARCH) LED on the DELAY scale. In all
delay modes, the DEL. POS. knob assumes the function of
DEL. POS. (delay position), and the hold off time defaults to
x1. Now the function of this knob (DEL. POS.) is to adjust the
delay time, indicated as a blanked part of the screen. The length
of the blanked sector depends on the DEL. POS. setting and
can be set between approx. one and six division after the nor­mal trace start position. As the trace right end is not effected,
the visible trace length is reduced. In delay (DEL) mode, the
trace will start from the normal left end where the blanking
starts. If the maximum delay is not sufficient, the time
coefficient must be increased (TIME/DIV left arrow pushbutton)
and the DEL. POS. knob set to the later starting point. To
return to normal (undelayed operation), depress the DELAY
pushbutton for a longer time or step through the different
DELAY functions until no LED on the DELAY scale is lit.

Photo 2

As the trigger point is always at the trace start position, trace
expansion in X direction with the aid of the timebase is limited
to the display on the left of the trace. Parts of the signal to
be expanded which are displayed near the trace end (right
side of the screen) are lost when the timebase speed is
increased (time coefficient reduced).

The delay function delays the trace start by a variable time
from the trigger point. This allows the sweep to begin on
any portion of a signal. The timebase speed can then be
increased to expand the display in X direction. With higher
expansion rates, the intensity reduces and within certain limits
this can be compensated by the INTENS knob setting.

If the display shows jitter, it is possible to select for (second)
triggering after the elapsed delay time (DTR).
As mentioned before, it is possible to display video signals
using the frame sync pulses for triggering (TV-F). After t he
delay time set by the operator, the next line sync pulse or
the line content may be used for triggering. So data lines and
test lines can be displayed separately.

Operation of the delay function is relatively simple. Without
delay function (no LED on the DELAY scale in the X field lit)
set the time coefficient setting (TIME/DIV) until 1 to 3 signal
periods are displayed. Display of less the one period should
be avoided as it limits the selection of the signal section to
be expanded, and may cause trigger problems.

The X MAG (x10) function should be switched off and the
time variable control should be in CAL position. The signal must
be triggered and stable. The following explanation assumes
that the trace starts on the left vertical graticule line.

MODE: SEA (SEARCH)
TIME/DIV: 5ms/div
Trigger coupling: TV-F
Delay time:
4div x 5ms = 20ms

Photo 2 shows that the delay time can be measured. It is
identical with the delayed position of the trace start and can
be calculated by multiplying the delay length measured in
div. and the actual calibrated time coefficient.
If in search (SEA) mode the next short depression of the
DELAY pushbutton switches over to DEL (LED lit).
The blanked period indicating the delay time is switched off
and the trace has its normal - unreduced-, lenght.
The trace starts on its previous X position (without DELAY
mode), beginning with the signal part first visible in search
(SEA) mode after the delay time. When the delay (DEL) mode
is in operation, it might even maximum intensity may not be
sufficient. In this case the timebase speed should be reduced
by increasing the time coefficient (TIME/DIV), to a slower
speed.

As mentioned before, the main purpose of the delay mode is
to make signal magnification in X direction possible.
This is the reason why the time coefficient in DEL mode
cannot be set to higher values than used during SEA (search)
operation. DEL mode speeds must always be faster.

Please note that the previous time coefficient chosen in DEL
and DTR mode is stored and automatically set after activating
one of those modes. If the stored time coefficient in DEL or

Subject to change without notice

17

DTR mode was higher than the actual value in SEA (search)

mode, the time coefficient in DEL or DTR mode is
automatically set to the value used during SEA (search)
operation.

Photo 3

MODE: DEL (DELAY)
TIME/DIV: 5ms/div
Trigger coupling: TV-F
Trigger slope: falling ( - )
Delay time: 20ms

Reducing the time coefficient (increasing the time base speed)
now expands the signal. If the signal start position is not set
to the optimum, it can still be shifted in the X direction by
turning the DEL. POS. knob. Photo 4 shows a 50 fold X
magnification caused by setting the time coefficient to 0.1ms/
div (5ms/div : 0.1ms/div = 50). The reading accuracy also
increases with higher X magnification. As already mentioned,
the time variable control must be in CAL position when
measurements are taken.

no LED on the DELAY scale is lit.
automatically to the operating conditions used before
switching over to DEL.

Please note: If the instrument is operated in Dual mode
under conditions where DUAL chopped mode is active, this
display mode is not switched off when time coefficients are
being reduced ( 0.2ms/div to 0.05µs/div ) for signal expansion
in DEL and DTR mode. Under certain conditions depending
on the signal frequency and the expansion rate, the unblanking
during the channel switching may become visible. The
chopper generator can be switched off under these conditions
by simultaneously depressing both arrow pushbuttons in the
TIME/DIV. sector. Any timebase change after this procedure
will switch the chopper generator on again. The chopper
generator then can be deactivated in the same way.

The instrument then is set

AUTO SET

As mentioned most of the controls and their settings are
electronically selected. The exceptions are the POWER and
the calibrator frequency pushbuttons, as well as the DEL.
POS./HOLD OFF, INTENS, FOCUS and TR (trace rotation)
controls. Thus automatic signal related instrument set up in
Yt (timebase) mode is possible.
In most cases no additional manual instrument setting is
required.

Photo 4

MODE: DEL (DELAY)
TIME/DIV: 0.1ms/div
Trigger coupling: TV-F
Trigger slope: falling ( - )
Delay time: 20ms

It is possible to trigger after the deleay time on the next
suitable slope. This avoids jitter which may occur when high
X magnification rates are used. Depressing the DELAY
pushbutton for a short time switches over from delay (DEL)
mode to triggered delay mode and the DTR LED lights. The
trigger settings ( automatic peak / normal triggering, trigger
coupling, TRIG. LEVEL and slope) already selected do not
change. In after delay triggering mode (DTR) the instrument
is automatically set to normal triggering (NM) and DC trigger
coupling (DC). Neither setting can be changed (NM, DC) and
the indicator LED‘s remain lit. Only the trigger level (TRIG.
LEVEL) and the trigger slope direction (±) can be used, for
selecting the signal part which should be used for triggering.
If the signal height is to small or the TRIG. LEVEL setting is
unsuitable, no trace appears, and the screen is dark.
Under these DELAY conditions a X position shift is possible
by varying the delay time (DEL. POS.) if the settings are
suitable. Unlike the untriggered delay mode (DEL) where a
continous shift is the result, in trigger after delay mode (DTR)
the signal jumps from one signal slope to the next with a
simple, repetitive signal, this may not be apparent in DTR
mode. In the case of TV trigger mode, triggering is possible
on line pulses and on continously repeating slopes in the
picture content.

The X magnification is limited by the decreasing trace
intensity. The 50 fold X magnification which was used for
the screen photos is just an example.

Depressing the delay pushbutton in DTR mode once again
switches back to the normal operating conditions where

Brief depressing of the AUTO SET pushbutton causes the
instrument to switch over to the last Yt mode settings
regarding CH I, CH II and DUAL. If the instrument was
operated in Yt mode, the actual setting will not be affected
with the exception of ADD mode which will be switched off.
At the same time the attenuator(s) (VOLTS/DIV) are
automatically set for a signal display height of approx. 6 div.
in mono channel mode or if in DUAL mode for approx. 4 div
height for each channel. This and the following explanation
regarding the automatic time coefficient setting assumes that
the pulse duty factor is approx. 1:1.

The time deflection coefficient is also set automatically for a
display of approx. 2 signal periods. The time base setting
occurs randomly if complex signals consisting several
frequencies e.g. video signals are present.

AUTO SET sets the instrument automatically to the following
operating conditions:

• AC input coupling

• Internal triggering

• Automatic peak (value) triggering

• Trigger level (TRIG. LEVEL) electrical midrange position
(the mechanical position may deviate)

• Y deflection coefficient(s) calibrated
(the fine control knob may not be in CAL position)

• Time deflection coefficient calibrated
(the fine control knob may not be in CAL position)

• AC trigger coupling

• DELAY mode switched off

• X x10 magnifier switched off

• Automatic X und Y position settings
(the mechanical knob position may deviate)

The automatically set operating conditions in AUTO SET
mode are taken over by the instrument regardless whether
the mechanical knob settings coincide or not. If a knob is not
in its calibrated detent (CAL), the LED stops blinking. Turning
the knob reverts to the actual mechanical setting.

The 1mV/div. and 2mV/div. deflection coefficient will not be
set by AUTO SET as the bandwidth is reduced in these
settings. This is indicated by red LED‘s on the scale.

18

Subject to change without notice

SA VE/RECALL

The instrument contains a non volatile memory in which the
actual instruments settings are stored when the instrument is
switched off. After switching on the oscilloscope and a short
internal check routine the last settings become active again.

The memory mentioned before can also be used by the
operator to save 6 different instrument settings and to recall
them. This relates to all settings with the exception off
INTENS, FOCUS, TR (trace rotation), DEL. POS./HOLD OFF
and the calibrator frequency pushbutton.

To

SAVE

a particular front panel set up:

RECALL

a front panel set up:

Press SAVE/RECALL pushbutton briefly. Now the trigger
coupling scale has the function of a memory location
indicator . The memory location number is indicated on the
left side of the scale below the S/R marking. After the
SAVE/RECALL pushbutton was briefly depressed for the
first time the S/R 1 (DC) LED will blink. The memory
location can now be chosen, selecting it by depressing
one of the NORM (up / down) pushbuttons; this causes
no change in the trigger coupling setting. SAVE the front
panel setting by depressing the SA VE/RECALL pushbutton
until LED stops blinking. The trigger coupling active before
starting the SAVE/RECALL procedure (and was saved)
then becomes active again.

To

Press SAVE/RECALL pushbutton briefly. Now the trigger
coupling scale has the function of a memory location
indicator . The memory location number is indicated on the
left side of the scale below the S/R marking. After the
SAVE/RECALL pushbutton was briefly depressed for the
first time the S/R 1 (DC) LED will blink. The memory
location can now be chosen, selecting it by depressing
one of the NORM (up / down) pushbuttons; this causes
no change in the trigger coupling setting. RECALL the front
panel setting by depressing the SA VE/RECALL pushbutton
briefly. The LED will stop blinking and the selected set up
is enabled. The LED display will now show the recalled
trigger coupling mode.

The test principle is fascinatingly simple. A built-in generator
delivers a sine voltage, which is 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 current-voltage characteristic of the test
object.

Since this circuit operates with a frequency of 50Hz (±10%)
and a voltage of approx. 7V max. (open circuit), the indicating
range of the component tester is limited. The impedance of
the component under test is limited to a range from 20Ω to

4.7kΩ. Below and above these values, the test pattern shows
only short-circuit or open-circuit. For the interpretation of the
displayed test pattern, these limits should always be borne
in mind. However , most electronic components can normally
be tested without any restriction.

Using the Component Tester

The instrument can be switched to component tester mode
by depressing COMP. TESTER pushbutton once. This is
completely independent from Yt or XY mode. In component
tester mode, only the X MAG. x10 LED may be lit if it was
previously enabled. Then the X trace length is expanded 10
fold. All other LED‘s are unlit.

The following description concerns the operation without X
MAG. x10, with a horizontal trace length of approx. 8 di v.
when the component tester input‘s are not connected. The
COMP. TESTER mode can be exited by depressing the COMP.
TESTER pushbutton again, setting the instrument back to
the previous mode and settings. The COMP. TESTER mode
can be saved and recalled as mentioned under SAVE/RECALL.

In component tester mode, the vertical preamplifier 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 COMP. TESTER mode, the only controls which
can be operated are INTENS., FOCUS, X-POS. and X MAG.
x10. All other controls except the X MAG. x10 have no
influence on the test operation.

The recalled operating conditions are taken over by the
instrument regardless of whether the mechanical knob
settings coincide or not. If a knob is not in its calibrated
detent (CAL), the LED stops blinking. Turning the knob
then reverts to the actual mechanical setting.

To interrupt a

If the SAVE/RECALL pushbutton was depressed
inadvertently, the procedure can be interrupted by
depressing any electronic selection pushbutton with the
exception of the SAVE/RECALL and NORM pushbuttons.

SAVE or RECALL

procedure:

Component Tester

The HM604-3 has a built-in electronic Component Tester
(COMP. TESTER), which is used for instant display of a test
pattern to indicate whether or not components are faulty.
The COMP. TESTER 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.

Subject to change without notice

For the component connection, two simple test leads with
4mm Ø banana plugs, and with test prod, alligator clip or
sprung hook, are required. The test leads are connected to
the insulated socket and the adjacent ground socket beneath
the screen. The component can be connected to the test
leads either way round.

Test Procedure

Caution! Do not test any component in live circuitry ­remove all grounds, power and signals connected to
the component under test. Set up Component Tester
as stated above. Connect test leads across component
to be tested. Observe oscilloscope display.

Only discharged capacitors should be tested!

Test Pattern Displays

In the following typical test patterns show various
components under test.

• Open circuit is indicated by a straight horizontal line.

• Short circuit is shown by a straight vertical line.

19

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 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.
Values of resistance from
evaluated. The determination of actual values will come with
experience, or by direct comparison with a component of a
known value.

2020

4.7k4.7k

20Ω to

4.7k Ω can be approximately

2020

4.7k4.7k

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 50Hz) 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 relatively
large capacitance or a relatively small inductance.

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

7V, their Z-breakdown, forms a second knee in the opposite
direction. A Z-breakdown voltage of more than 6.8V can not
be displayed.

Type: Normal Diode High Voltage Diode Z-Diode 6.8V
Terminals: Cathode-Anode Cathode-Anode Cathode-Anode

Connections: (CT-GD) (CT-GD) (CT-GD)

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-emitter,
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 T ransistor

The values of capacitance of normal or electrolytic capacitors

0.10.1

FF

10001000

from

0.1µ

F to

0.10.1
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 50Hz) of an inductor in
the range from 20Ω to 4.7kΩ can easily be obtained or
compared.

FF

FF

1000µ

F can be displayed and approximate

10001000

FF

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 conducting
state. It should be noted that both the forward and the reverse
characteristic are displayed simultaneously. This is a two­terminal test, therefore testing of transistor amplification is
not possible, but testing of a single junction is easily and
quickly possible. Since the test voltage applied is only very
low, 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
diodes. Possibly only a small portion of the knee is visible. Z­diodes always show their forward knee and, up to approx.

Terminals: b-e b-c e-c
Connections: (CT-GD) (CT-GD) (CT-GD)

P-N-P Transistor

Terminals: b-e b-c e-c
Connections: (CT-GD) (CT-GD) (CT-GD)

For a transistor the figures b-e and b-c are important. The
figure e-c can vary; but a vertcal 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 COMP. TESTER, the distinction between a
P-N-P to an N-P-N transistor is discenible. In case of doubt,
comparison with a known type is helpful. It should be noted
that the same socket connection (COMP. TESTER or 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.

In-Circuit Tests

Caution! During in-circuit tests 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 both COMP. TESTER leads are
not isolated against the circuit under test.

20

Subject to change without notice

In-circuit tests are possible in many cases. However, they
are not well defined. This is caused by a shunt connection of
real or complex impedances - especially if they are of relatively
low impedance at 50Hz - 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
COMP. TESTER socket avoiding hum distortion of the test
pattern.

Ω

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 cir cuit), which
is not defective. The test patterns show some typical displays
for in-circuit tests.

µ

Ω

Ω Ω

Subject to change without notice

µ Ω

21

22

Subject to change without notice

Test Instructions
General

These Test Instructions are intended as an aid for checking
the most important characteristics of the HM604-3 at regular
intervals without the need for expensive test equipment.
Resulting corrections and readjustments inside the
instrument, indicated by the following tests, are described in
the Service Instructions or on the Adjusting Plan. They should
only be undertaken by qualified personnel.

As with the First T ime Operation instructions, care should be
taken that all knobs with arrows are set to their calibrated
positions. Depress AUTO SET for default settings. It is
recommended to switch on the instrument for about 20
minutes prior to the commencement of any check.

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

Normally, the CRT of the HM604-3 has very good brightness.
Any reduction of this brightness can only be judged visually.
However, decreased brightness may be the result of wrong
settings or reduced high voltage. The latter is easily
recognized by the greatly increased sensitivity of the vertical
amplifier. Correct setting means, that the HOLD OFF control
should be turned to the left stop; the X-MAG. x10 function
should be switched off; a medium time coefficient should be
selected; line triggering (~ indicated) should be used only
with a suitable TIME/DIV. setting (e.g. 2ms/div.). 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 INTENS. control (particularly when in
XY mode), while with the control at the right hand stop the
focus and the line width are just acceptable.

With maximum intensity the timebase fly-back must on no
account be visible. Visible trace fault without input signal:
bright dot on the left side or decreasing brightness from left
to right or shortening of the baseline. (Cause: Incorrect
Unblanking Pulse.)
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
regulation circuitry for the high voltage supply. The presetting
pots for the high voltage circuit, minimum and maximum
intensity, are only accessible inside the instrument.

A 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-linearity
and the raster distortion in the marginal zone of the screen in
accordance with international standards (see CRT data book).
These limit values are strictly supervised by HAMEG. The
selection of a cathode-ray tube without any tolerances is
practically impossible.

Astigmatism Check

Check whether the horizontal and vertical sharpness of the
display are equal. This is best seen by displaying a square­wave signal with the repetition rate of approximately 1MHz.
Focus the horizontal tops of the square-wave signal 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 astigmatism
control is necessary. A potentiometer of 47kΩ is provided
inside the instrument for the correction of astigmatism. A
certain loss of marginal sharpness of the CRT is unavoidable;
this is due to the manufacturing process of the CRT.

Symmetry and Drift of the Vertical Amplifier

Both of these characteristics are substantially determined
by the input stages of the amplifiers.

The symmetry of both channels and the vertical final amplifier
can be checked by inverting Channel I and II (depress the
corresponding INV pushbutton). The vertical position of the
trace should not change by more than 0.5div. However, a
change of 1div. 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 Y-POS. controls. A sine­wave signal of 10-100kHz is applied to the amplifier input. When
the Y-POS. control is then turned fully in both directions from
stop to stop with a display height of approximately 8div., the
upper and lower positions of the trace that are visible should
be approximately of the same height. Differences of up to
1div. are permissible (input coupling should be set to AC).

Checking the drift is relatively simple. 20minutes after
switching on the instrument, set the baseline exactly on the
horizontal center line of the graticule. The beam position must
not change by more than 0.5div. during the following hour.

Calibration of the Vertical Amplifier

Two square-wave voltages of 0.2Vpp ±1% and 2Vpp are
present at the output sockets of the calibrator (CAL.) If a
direct connection is made between the 0.2V output and the
input of the vertical amplifier (e.g. using a x1 probe), the
displayed signal in the 50mV/div. position (variable control to
CAL.) should be 4div. high (DC input coupling). Maximum
deviations of 0.12div. (3%) are permissible. If a x10 probe is
connected between the 2V output and Y input, the same
display 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 in the attenuator sector fully counter­clockwise, the input sensitivity is decreased at least by the
factor 2.5 in each position. In the 50mV/div. position, the
displayed calibrator signal height should vary from 4div. to at
least 1.6div.

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 risetime (max. 5ns). The signal coaxial 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 100Hz, 1kHz, 10kHz, 100kHz and 1MHz, the
deflection coefficient should be set at 5mV/div. with DC 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 1MHz
and a display height of 4-5div.. At the same time, the leading
top corner of the pulse must not be rounded. In general, no
great changes occur after the instrument has left the factory,
and it is left to the operators discretion whether this test is
undertaken or not. A suited generator for this test is HZ60
from HAMEG.

Subject to change without notice

23

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
frequency-compensated in each position. Even small
capacitive changes can reduce the transmission performance.
Faults of this kind are as a rule most easily detected with a
square-wave signal with a low repetition rate (e.g. 1kHz). If a
suitable generator with max. output of 40Vpp is available, it
is advisable to check at regular intervals the deflection
coefficients on all positions of the input 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 1MΩ ±1% resistor and, in parallel with it, a
trimmer 3-15pF in parallel with approx. 12pF. One side of
this parallel circuit is connected directly to the input connector
of CH.I or CH.II 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 5mV/div. position (variable control
to CAL., DC input coupling; square tops exactly horizontal;
no ramp-off is permitted). This is achieved by adjusting the
trimmer located in the 2:1 attenuator . The shape of the square­wave should then be the same in each input attenuator
position.

Operating Modes: CH.I/II, DUAL, ADD,
CHOP., INVERT and X-Y Operation

In DUAL mode two traces must appear immediately. On
actuation of the Y-POS. controls, the trace positions should
have minimal 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

0.5mm.
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 TIME/DIV. switch to 0.5ms/
div., 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
+2div., the other to a -2div. vertical position from the hori­zontal center line of the graticule.

Do not try to synchronize (with the time variable control) the
chop frequency (0.5MHz)! Check for negligible trace widening
and periodic shadowing when switching between 0.5ms/div
and 0.2ms/div.

It is important to note that in the I+II add mode (ADD LED
lights) or the I-II difference mode (one INV LED lights) the
vertical position of the trace can be adjusted by using both
the Channel I and Channel II Y-POS. controls.

In X-Y Operation (XY LED in TIME/DIV sector lights), 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
4div. when the deflection coefficient is set to 50mV/div.
position (variable control set to its CAL. position). The check
of the mono channel display is unnecessary; it is contained
indirectly in the tests above stated.

It should be approx. 0.3-0.5div. for the HM604-3. An increased
trigger sensitivity creates the risk of response to the noise
level in the trigger circuit. 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
50Hz and 1MHz. The instrument should be in automatic peak
(value) triggering (NM LED dark) and the TRIG. LEVEL knob
in midrange position. It should be ascertained whether the
same trigger sensitivity is also present with Normal Triggering
(NM LED lights). In this trigger mode, TRIG. LEVEL
adjustment is absolutely necessary.

The checks should show the same trigger threshold with
the same frequency. On depressing the ± (SLOPE) button,
the start of the sweep changes from the positive-going to
the negative-going edge of the trigger signal.

As described in the Operating Instructions, the trigger
frequency range is dependent on the trigger coupling
selected. For lower frequencies the LF coupling mode can
be selected. In this mode, triggering up to at least 1.5kHz
(sine-wave) is possible. Internally the HM604-3 should trigger
perfectly at a display height of approx. 0.5div., when the
appropriate trigger coupling mode is set.

For external triggering (EXT LED lights), the TRIG. INP.
connector requires a signal voltage of at least 0.3Vpp, which
is in synchronism with the Y input signal. The voltage value
is dependent on the frequency and the trigger coupling mode
(AC-DC-HF-LF).

Checking of the TV triggering is possible with a video signal
of any given polarity.

Use the TV-L or TV-F setting for video sync pulse separation.
With the ± (SLOPE) button the correct slope of the sync
pulse (front edge) must be selected and a suited TIME/DIV
setting must be chosen. The slope is then valid for both sync
frequencies.

Perfect TV triggering is achieved, when in both display modes
the amplitude of the complete TV signal (from white level to
the top of the line sync pulse) is limited between 0.8 and
6div and sync pulses of more then 0.5 div. height. The display
should not shift horizontally during a change of the trigger
coupling from AC to DC when displaying a sine-wave signal
without DC offset.

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 switching from
TRIG I to TRIG II or when the trigger coupling is changed
from AC to DC.

Checking of the line/mains frequency triggering (50-60Hz) is
possible, when the input signal is time-related (multiple or
submultiple) to the power line frequency ( ~ LED lights). There
is no trigger threshold visible in this trigger mode. Even very
small input signals are triggered stably (e.g. ripple voltage).
For this check, use an input of approx. 1V. The displayed
signal height can then be varied by turning the respective
input attenuator switch and its variable control.

Timebase

Triggering Checks

The internal trigger threshold is important as it determines
the display height from which a signal will be stably displayed.

24

Before checking the timebase it should be ascertained that
the trace length is approx. 10div. in all time ranges. If not, it
can be corrected with the potentiometer X x1. This
adjustment should be made with the TIME/DIV. switch in a

Subject to change without notice

mid position (i.e. 20µs/div.). Prior to the commencement of
any check set the time variable control to CAL. The X-MAG.
x10 LED should not light. This condition should be maintained
until the variation ranges of these controls are checked.
Check that the sweep runs from the left to the right side of
the screen (TIME/DIV. setting to 0.1s/div.; X-POS. control in
mid-range). This check is only necessary after changing the
cathode-ray tube.
If a precise marker signal is not available for checking the
Timebase time coefficients, then an accurate sine-wave
generator may be used. Its frequency tolerance should not
be greater than ±1%. The timebase accuracy of the HM604­3 is given as ±3%, but it is considerably better than this. For
the simultaneous checking of timebase linearity and accuracy
at least 10 oscillations, i.e. 1 cycle every div., should always
be displayed. For precise determination, 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.
If a precise Time Mark Generator is used for checking, Nor­mal Triggering (NM LED lights) and TRIG. LEVEL control
adjustment is recommended.

The following table shows which frequencies are required
for the particular ranges.

0.5s/div. - 2Hz 0.1ms/div. - 10kHz

0.2s/div. - 5Hz 50µs/div. - 20kHz

0.1s/div. - 10Hz 20µs/div. - 50kHz
50ms/div. - 20Hz 10µs/div. - 100kHz
20ms/div. - 50Hz 5µs/div. - 200kHz
10ms/div. - 100Hz 2µs/div. - 500kHz
5ms/div. - 200Hz 1µs/div. - 1MHz
2ms/div. - 500Hz 0.5µs/div. - 2MHz
1ms/div. - 1kHz 0.2µs/div. - 5MHz

0.5ms/div.- 2kHz 0.1µs/div. - 10MHz

0.2ms/div.- 5kHz 0.05µs/div. - 20MHz

When the X-MAG. x10 function is active, a marker or cycle
peak will be displayed every 10div. ±5% (with variable control
in CAL. position; measurement in the 5µs/div. range). The
tolerance is better measurable in the 50µs/div. range (one
cycle every 1div.).

Holdoff time

The variation of the holdoff time while turning the HOLD OFF
knob can not be tested without opening the instrument.
However , a visual check can be made if the instrument is not
operated in DELAY mode.
Without an input signal, set TIME/DIV . to 0.05µs/div and time
variable control cw, use automatic peak (value) triggering. At
the left hand stop of the HOLDOFF knob, the trace should
be bright. It should noticeably darken at the right hand stop
of the HOLDOFF knob.

Component Tester

After selecting component tester mode by pressing the
COMP. TESTER button, a horizontal straight line should
appear immediately, when the COMP. TESTER socket is open.
The length of this trace should be approx. 8div if the X MAG.
x10 LED is dark. With connection of the COMP. TESTER
socket to the ground jack in the Y-Section, a vertical straight
line with approx. 6div. height should be displayed. The above
stated measurements have some tolerances.

Trace Alignment

The CRT has an admissible angular deviation ±5° between
the X deflection plane D1-D2 and the horizontal center line of

the internal graticule. This deviation, due to tube production
tolerances (and only important after changing the CRT), and
also the influence of the earths magnetic field, which is
dependent on the instruments North orientation, are
corrected 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 HM604-3 in its closed case, an angle of
rotation ±0.57° (0.1div. difference in elevation per 10div.
graticule length) is sufficient for the compensation of the
earths magnetic field.

Service Instructions
General

The following instructions are intended as an aid for the
electronic technician, who is carrying out readjustments on
the HM604-3, 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 for service or
repair (see also Warranty).

Instrument Case Removal

The rear cover can be taken off after unplugging the power
cords triple-contact connector and after two nuts the washers
have been removed. If a cross recessed pan head screw is
present on the bottom of the instrument, it must be removed
too. 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 -2025V and +12kV and to the operating
voltages for both final amplifier stages 115V and 66V . Poten­tials of these voltages are on the PS-Board, the CRT-PCB, on
the upper and lower PCBs. Such potentials are moreover on
the checkpoint strips on the upper and lower horizontal PCBs.
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 and the
opto-coupler. For the same reason it is very risky to connect
capacitors to these points while the instrument is on.

Capacitors in the instrument may still be charged, even when
the instrument is disconnected from all voltage sources.
Normally, the capacitors are discharged approx. 6 seconds
after switching off. However, with a defective instrument an
interruption of the load is not impossible. Therefore, after
switching off, it is recommended to connect one by one all
terminals of the check strips on the upper PCB across 1kΩ
to ground (chassis) for a period of 1 second.

Subject to change without notice

25

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).

The complete instrument (with case closed and POWER
button depressed) is after each intervention undergo a
voltage test with 2200V, DC, between accessible parts to
both mains/line supply terminals. This test is dangerous and
requires an adequately trained specialist.

Operating Voltages

All operating voltages ( +12V, -12V, +115V, +66V, -2025V)
are stabilized by the switch mode power supply. The +12V
supply is further stabilized and used as a reference voltage
for -12V stabilisation. These different operating voltages are
fixed voltages, except the +12V, which can be adjusted. The
variation of the fixed voltages greater than 5% from the no­minal value indicates a fault. Measurements of the high
voltage may only be accomplished by the use of a sufficient
highly resistive voltmeter (>10MΩ). Y ou must make absolutely
sure that the electric strength of the voltmeter is sufficiently
high. It is recommended to check the ripple and also the
interaction from other possible sources. Excessive values
might be very often the reason for incomprehensible faults.

Maximum and Minimum Brightness

Two variable resistors (470kΩ), located on the switch mode
power supply PCB, are used for these adjustment procedures.
They may only be touched by a properly insulating screwdriver

Caution! High voltage!

(
to be repeated, because the functions of both variable
resistors are dependent on each other. Correct adjustment
is achieved, when the trace can be blanked in XY mode and,
in addition, when the requirement described in the Test
Instructions are met.

). The adjustments may possibly have

Astigmatism control

The ratio of vertical and horizontal sharpness can be adjusted
by the variable resistor of 47kΩ, located on the CRT PCB. As
a precaution however, the voltage for the vertical deflecting
plates (approx. +42V when the trace is in center position)
should firstly be checked, because this voltage will affect
the astigmastism correction. While the adjustment is being
carried out (with medium brightness and a 1MHz square­wave signal), the upper horizontal square-wave tops are firstly
focussed with the FOCUS control. Then the sharpness of
the vertical lines are corrected with the 47kΩ Astigm. pot.
The correction should be repeated several times in this
sequence. The adjustment is optimised, when the FOCUS
knob exclusively brings no improvement of the sharpness in
both directions.

Trigger Threshold

The internal trigger threshold should be in the range 0.3 to

0.5div. display height. It is strongly dependent on the
comparator IC. If there are compelling reasons to replace
this comparator, it may be that triggering becomes too sen­sitive or too insensitive caused by the IC gain tolerances (see
Test Instructions: „Triggering Checks“). In extreme cases,
the hysteresis resistor of the comparator should be changed.
Generally, max. halving or doubling of this resistance value
should be sufficient. A too small trigger threshold cause
double-triggering or premature trigger action due to
interference pulses or random noise. A too high trigger
threshold prevents the display of very small display heights.

Trouble-Shooting the Instrument

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 voltages 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 discolored components (caused by overheating).
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 PCBs, to front
chassis parts, to CRT PCB, to trace rotation coil (inside of
CRTs shielding), and to the control potentiometers and
switches on top of and beneath the PCBs. 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 important step

- after checking the power fuses - will be to measure the
deflecting plate voltages of the CRT. In almost any case, the
faulty section can be located. The sections represent:

1. Vertical deflection. 2. Horizontal deflection.

3. CRT circuit. 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 approx.
42V and X approx 60V). 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.

Adjustments

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 Plan. 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 determined. 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.

26

Subject to change without notice

RS232 Interface - Remote Control

Command definition

The oscilloscope is supplied with a serial interface for
control purposes. The interface connector (9 pole D- SUB
female) is located on the rear of the instrument. Via this
bidirectional port, the instrument parameter settings can
be transmitted to a PC or received from a PC. The
attached disk contains example programs.

The maximum connecting cable length must not exceed
3 meters and must contain 9 lines connected 1:1.

The pin connection of the RS232 interface (9 pole D­SUB female) is determined as follows:

Pin

2 Tx data (data from oscilloscope to external device)
3 Rx data (data from external device to oscilloscope)
5 Ground (reference potential - connected via the

oscilloscope‘s power cord with protective earth)

The maximum voltage swing at pin 2 resp. pin 3 is ± 12
volt. The RS232 parameter are:

N-8-2 ( no parity bit, 8 data bits, 2 stop bits, XON/XOFF
protocol)

Baud-Rate Setting

After the first POWER UP ( switching on of the
oscilloscope ) and the first command CR (0D hex) sent
from the PC, the baud rate is recognized and set
automatically between 110 baud and 19200 baud. Then
the oscilloscope transmits the RETURNCODE: 0 CR LF
to the PC. The oscilloscope is then switched over to
REMOTE control mode. In this status all settings (with
the exception of INTENS, FOCUS, TR and CAL
frequency) can be controlled by the PC only.

The only ways to quit this status are:

• Switching the oscilloscope off,

• depressing the AUTO SET ( LOCAL ) pushbutton or
transmitting the command

• RM= 0 from the PC to the oscilloscope.

If at the beginning no CR command is recognizable, the
oscilloscope pulls the TxD line low for approx. 0.2ms
and causes a break on the PC.

Data Communication

After successfully being set to remote control mode,
the oscilloscope is prepared for command reception. The
following commands are available:

Query ? asks for parameter
Allocation = sets parameter
Status : declares actual parameter
Binary data [ b ]
ASCII data [ a ] data field consists of ASCII data
ASCII number [ n ] integer ASCII parameter
Binary data [ array ] data field consists of binary data
Terminator ( CR LF) carriage return and/or line feed
Return code [ R ] ASCII parameter

data field consists of 1 byte binary data

Kommand: Rückgabe Beschreibung

→→

PC

→Scope Scope

→→

ID? ID:Daten(CR LF) data consits of: instrument
(CR) [R](CR LF) remote status and baud rate
TRSTA? TRST A:[b](CR LF)

TRSTA=[b] [R](CR LF) reset Trigger
RM? RM: [a](CR LF) query for remote status
RM=[a](CR LF) [R](CR LF) change remote status
LK? LK=[a](CR LF) interlock request: LK:

LK=[a](CR LF) [R](CR LF) interlock setting for LOCAL
VER? VER:[a](CR LF) query for software version

HELP? HELP: [a](CR LF) query for command listing
DDF? DDF:[array] query for instrument data field
DDF=[array] [R](CR LF) transmits new data field to the

SA VEDF=[n] [R](CR LF) stores instrument data field in
RECDF=[nl [R](CR LF) recall‘s instrument data field
POSY 1? POSY1: [b] query for CH I position setting

POSY1=[b] [R](CR LF) sets CH I Y-position
POSY2? POSY1: [b] query for CH II position setting
POSY2=[b] [R](CR LF) sets CH II Y-position
VA RY 1? VARY1: [b] query for CH I VAR 2.5:1 setting
VAR Y1=[b] [R](CR LF) sets CH I VAR 2.5:1
VA RY2? VARY2: [b]
VAR Y2=[b] [R](CR LF) sets CH II VAR 2.5:1
VAR TBA VARTBV[b]
VAR TB1=[b] [R](CR LF) sets TBI TIME-VAR
TRLEV? TRLEV:[b]
TRLEV=[b] [R](CR LF) sets Trigger -Level
XPOS? XPOS:[b]
XPOS=[b] [R](CR LF) sets X-Position
CH1? CH1:[b] query CH I settings (deflection

CH1=[b] [R](CR LF) sets CH I (deflection
CH2? CH1:[b] query CH II settings (deflection
CH2=[b] [R](CR LF) sets CH II (deflection
MODE? MODE:[b] query for oscilloscope mode
MODE=[b] 1[R](CR LF) sets oscilloscope mode (Yt, XY,
TB1? TB1: [b] query for timebase setting

TB1=[b] [R](CR LF) set timebase
TB2? TB2:[b] query for timebase setting in

TB2=[b] [R](CR LF)
TRIG? TRIG: [b] query for trigger parameter
TRIG=[b] [R](CR LF) set trigger parameter
TRVAL TR V AL: [array] query for signal amplitude at

→→

→PC

→→

type, manufacturer
acceptance

query for trigger status (data bit 0)

1 → locked
0 → unlocked

(Auto Set) pushbutton

scope
instrument memory n (1-6)
from instrument memory n (1-6)

query for CH II V AR 2.5:1 setting
query

TB1 TIME-VAR
query for
query

coefficient, INV , GD, AC/DC)
coefficient, INV , GD, AC/DC)
coefficient, INV , GD, AC/DC)
coefficient, INV , GD, AC/DC)
setting (Yt, XY , COMP. TESTER)
COMP. TESTER)

T rigger-Level

X-Position

DELand DTR mode
set timebase in DEL and DTR mode

trigger amplifier output,INTEGER
1st word = positive peak value
2nd word = negative peak value
3rd word = peak to peak value
3rd word = peak to peak value
4th word = reference potential
for positive and negative peak
values
Rating: approx. 20mV/LSB and
250mV/div.

Command Chart:

Commands cause the instrument to reply with parameter or
a RETURN CODE transmission. You must then wait for the
end of transmission before the next command is sent from

Subject to change without notice

27

the PC to the oscilloscope, otherwise it results in a buffer
overflow. The setting of the oscilloscope is made via the In­strument Data Field (Device Data Field = DDF) as a binary
array. Each byte of the data field can also be called-up by a
single command. The following chart shows the structure
and the appertaining single commands:

Instrument Data Field with Single Commands

Kommand: D7 D6 D5 D4 D3 D2 D1 D0
CH1 GND AC INV1 ON VALUE Counter 0-13
CH2 GND AC INV2 ON VALUE Counter 0-13

MODE CT XY A-TR CHOP ADD 0

TB1 x10 0 0 TB-A TIME Counter 1-26

TB2 0 DEL-MODE TB-B TIME Counter 1-26

off = 00
SEA = 01
DEL = 10 50ns/DIV = 00 bis
DTR = 11 50ms/DIV = 12hex

TRIG ± 0 P-P NORM 0 COUPLING 0-6

TRLEV 8-BIT
VAR TB1 8-BIT
VARY 2 8-BIT
VARY 1 8-BIT
XPOS B-BIT
POSY2 8-BIT
POSY1 8-BIT

mv/DIV = 0000
20V/DIV = 1101

TR-SOURCE
00=Y1
01=Y2
1x=EXT

50ns/DIV = 00 bis
0,5s/DIV = 15hex

AC=00, DC=01
HF=02, LF=03
LINE=04
TV-F =05
TV-L =06

The data field is internally checked for logical errors which
are protocolled in the RETURN CODE.
The following RETURN CODES are implemented:

0 = no error 1 = syntax error 2 = data error
3 = buffer overflow 4 = bad data set

28

Subject to change without notice

Short instruction for HM604-3

Switching on and initial setting

Case, chassis and all measuring terminals are connected to the safety earth conductor (Safety Class I).
Connect instrument to power outlet, depress red POWER button. LED‘s indicating operating condition.
Instrument is set as it was before switching off.
Adjust trace intensity for medium brightness.
If no trace is visible, depress AUTO SET to switch to Yt mode.
Focus trace using FOCUS.

Vertical amplifier mode

Channel I: If no LED lit on the CH I VOLTS/DIV scale, depress pushbutton CH I. If a LED on the CH II
VOLTS/DIV. is lit too, depress pushbutton CH II to switch it off.
Channel II: If no LED lit on the CH II VOLTS/DIV scale, depress pushbutton CH II. If a LED on the CH I
VOLTS/DIV. is lit too, depress pushbutton CH I to switch it off.
DUAL (channel I and channel II): Depress the CH I or CH II pushbutton so that a LED is lit on both channel I and
II VOLT/DIV scales.

Addition (ADD): Depress both CH I and CH II pushbuttons simultaneously until the ADD LED lights.
Addition (sum): With both input signals in phase switch both INV LED‘s on or both off.
Addition (difference): With both input signals in phase switch only one INV LED on.
Addition mode can be exited by depressing both CH I and CH II pushbuttons simultaneously until the ADD LED is dark.

Triggering mode

Select trigger mode by depressing both NORM pushbuttons simultaneously:
NM LED dark = automatic peak (value) triggering < 20 Hz - 100 MHz. TRIG. LEVEL active.
NM LED lit = normal triggering. TRIG. LEVEL active.

Trigger edge direction: select with ± pushbutton. - LED lit = falling slope, dark = rising slope.
Internal triggering: In CH I and CH II mode automatically set and indicated by TR I and TR II LED‘s.
In DUAL and ADD mode briefly depress the TRIG. pushbutton for switching over.
Internal alternate triggering: IN DUAL mode depress and hold the TRIG. pushbutton until both TR I and TR II are lit.
Switch off this mode by briefly depressing the TRIG. pushbutton.
External triggering: Depress the EXT pushbutton next to the TRIG. INP. BNC socket to light the EXT LED.
T rigger Signal 0.3Vpp - 3Vpp at TRIG. INP. Return to internal triggering by depressing the EXT. pushbutton again (EXT LED dark).
Line triggering: Select the ~ symbol on the trigger coupling scale depressing one of the NORM pushbuttons (up / down).
Trigger coupling: Choose AC/DC/HF/LF/TV-L/TV-F by depressing one of the NORM pushbuttons.
Frequency ranges: AC 10 Hz - 100 MHz; DC 0 Hz - 100MHz; HF 1.5kHz - 100 MHz; LF 0 Hz - 1.5 kHz.
TV-L to trigger on line sync. pulses; T V-F to trigger on separated frame sync. pulses. Select ± (SLOPE) for the
leading slope. Sync pulse above picture content = + ( - LED dark ), below = - ( - LED lit ).
Pay attention to trigger indicator: LED above TRIG.

Measurements

Apply test signal(s) to the vertical input connectors of CH I and/or CH II .
Before use, compensate attenuator probe with built-in square wave generator CAL.
Depress AUTO SET for automatic instrument set up or:
Select AC or DC ( LED lit) input coupling (GD LED dark).
Adjust signal to desired display height with < > arrow pushbutton(s) in VOLTS/DIV. sector.
Amplitude measurement with Y fine control (VAR. 2.5:1) at right stop.
Adjust signal to desired number of displayed periods with < > arrow pushbutton(s) in TIME/DIV. sector.
Time measurement with time fine control (VAR. 2.5:1) at right stop.
Time expansion with x10 LED lit.
Set trigger point with TRIG. LEVEL knob in automatic peak (value) and normal (NM LED lit) triggering.
Select automatic peak (value) or normal triggering by depressing both NORM pushbuttons simultaneously.
Improve complex or aperiodic signal stability with longer HOLD OFF-time or in DELAY mode (DEL or DTR).
For the expansion of signal portions, use delay (DEL) or after delay trigger mode (DTR) with reduced

time coefficient (TIME/DIV).
Normal undelayed mode = no DELAY LED (SEA/DEL/DTR) lights.
Depress DELAY pushbutton once (SEA - search - LED lights) and adjust the timebase start position using

DEL. POS. knob and TIME/DIV < > pushbutton(s).
Brief depress DELAY pushbutton to switch over to delay mode (DEL lights). Now the timebase starts (DEL lit)

with the selected start point and the trace length has full length. For start point and expansion rate corrections use
DEL. POS. and TIME/DIV settings.
Depressing the DELAY pushbutton once again switches over to triggered delay mode (DTR lights) and

automatically to DC trigger coupling (DC LED on TRIG scale lights) and normal triggering (NM LED lights).
± (SLOPE) and TRIG. LEVEL are active and set in their priviously used settings.
Depress the DELAY pushbutton again to switch to normal mode. Then all LED‘s on the DELAY scale are dark.
SEA and DEL can be exited without stepping through the modes by depressing and holding the DELAY

pushbutton until all LED‘s are dark.

Component tester mode

Depress COMP. TESTER pushbutton.
COMP. TESTER mode is active if all LED‘s are dark (exception X MAG. x10).

In-circuit-test: Circuit under test must be disconnected from battery or power (pull out power plug), signals and

ground (earth). Remove all signal connections to the instrument (cable, probe), then start testing.

Subject to change without notice

29

Front Panel Elements HM 604-3 (Brief Description - Front View)

Element Function

POWER Turns scope on and off.
(pushbutton) I = ON; O = OFF

FOCUS Focus control for trace sharpness (mechanical).
(knob)

TR Trace rotation (mechanical). To align trace with

horzontal field.(potentiometer; graticule line.
Compensates adjustment with influence of Earth’s
magnetic screwdriver)

INTENS. Intensity control for trace brightness.
(knob) (mechanical)

X-POS. Controls horizontal position of trace.
(knob)

AUTO SET Automatic signal related instrument setting. If in XY
(pushbutton) or COMP . TESTER mode, the instrument switches
(RS232/Local) over to Yt (DUAL or MONO) mode. The electrical

settings are taken over independent from the
mechanical knob settings. Turning the knob reverts
to the actual mechanical knob setting.

X-MAG. x10 10:1 expansion in the X direction (LED lit). direction
(pushbutton (LED lit). Max. resolution 5ns/div.
+ LED)

XY Selects X-Y operation, stops sweep and reverse.
(pushbutton X signal via CH. II.Caution! Phosphor burn-in
+ LED (15)) without X signal.

ElementElement

Element

ElementElement

Trigger Coupling

(LED scale)

+/- (SLOPE) Selects the slope of the trigger signal. LED dark =
(pushbutton rising edge. LED lit ( - ) = falling edge.
+ LED )

TRIG. LEVEL Adjustment of trigger level (knob) in automatic peak
(knob) (value) and normal triggering.

DEL. POS. Controls holdoff-time between sweeps. Normal
HOLD OFF HOLD OFF position = full ccw (x1). In DELAY mode

(knob) for delay time adjustment; hold off defaults to x1.

NORM Depressing both pushbuttons simultaneously swit­(pushbuttons ches over from automatic peak (value) triggering
+ „NM“ LED) (NM LED dark) to normal triggering (NM LED lit)

CAL. 1kHz/1MHz

(pushbutton switch)

0.2Vpp - 2Vpp Calibrator square wave output, 0,2Vpp or 2Vpp.
(test sockets)

FunctionFunction

Function

FunctionFunction

Indicates trigger coupling:
AC: <20Hz - 100MHz DC: 0 - 100MHz
HF: 1.5kHz - 100MHz LF: 0 - 1.5kHz
~ : Internal line triggering TV-L: Triggering for TV-line
TV-F: Triggering for TV-frame. Selectable by
buttons (22).

and reverse.

Selects calibrator frequency.
Button released: approx. 1kHz,
Button depressed: approx. 1MHz. (mechanical)

NORM

DELA Y Selects DELAY mode and reverse. SEA = search,
(pushbutton) DEL= delay and DTR = after delay trigger. Delay

DELA Y Indicates the delay mode. Dark = off, SEA = select
(LED scale) delay time, DEL = delayed display and DTR =

SAVE/RECALLBriefly depressing calls the set-up memories;
(pushbutton) LED(18) blinks. Memory location selection (S/R

TIME/DIV. Selects time coefficients of timebase, from 0.5s/
(< > pushbuttons)

TIME/DIV. Indicates time coefficient. Blinking indicates uncali­(LED scale) brated setting of (14). In seconds ranges the sec

VAR. 2.5:1 V ariable adjustment of (knob) timebase. Decreases

XY Indicates XY mode. Dark in Yt (LED) and COMP.
(LED) TESTER mode.

S/R 1-6 Memory location indicator . Blinking indicates SA VE/

(scale) RECALL (scale) mode and memory location.

time settig by DEL. POS. (21) and time coefficient
(TIME/DIV. (12)).

triggered display after delay.

scale (16)) by NORM buttons (22). Briefly press
SAVE/RECALL for RECALL. Press SA VE/RECALL
until LED stops blinking to SAVE.

div. to 0.05µs/div. < pushbutton increases >
pushbutton decreases time coefficient. In SEA
(search) DELAY mode, selects for coarse setting
of delay time.

LED is also lit.

X deflection speed at least 2.5 fold at left stop. For
time measurements turn to right hand stop.

COMP . TESTER

(4mm jacks)

COMP . TESTER

(pushbutton) component tester mode and reverse.

Y-POS.I Controls vertical position of channel I display.
(knob)

INV Inversion of CH. I display (INV LED lit) and reverse.
(pushbutton In combination with ADD button = difference CH. II
+ LED) CH. I.

INPUT CH I Channel I signal input. Input impedance 1MΩII20pF.
(BNC connector)

AC-DC Selects input coupling of CH. I vertical amplifier.
(pushbutton DC = direct coupling (LED lit) AC = coupling via
+ „DC“ LED) capacitor (LED dark).

GD GD (LED lit) = signal disconnected from input, Y
(pushbutton + LED)

VOLTS/DIV. Channel I input attenuator.
(pushbuttons <> pushbuttons select Y input sensitivity in mV/div.
LED scale) or V/div . in 1-2-5 sequence. Deflection coefficient

VAR. 2.5:1 Fine adjustment of Y amplitude CH. I. Increases
(knob) attenuation factor min. by 2.5 (left hand stop). For

Connectors for test leads of the Component tester.

Switch to convert oscilloscope from Yt or XY to

amplifier input grounded.

LED blinking = uncalibrated.

amplitude measurement must be in CAL. position
(right hand stop).

30

TRIG.

LED above indicates trigger (LED) action (sweep triggered).

Subject to change without notice

Element Function Element Function

CH I & CH II Pushbuttons for Mono CH I and CH II, DUAL and
(pushbuttons + ADD selection. Mode indication by LED(s) deflecti­„ADD“ LED) on coefficient coefficient scale. In Yt mode at least

one LED on a scale lit. T o switch over to the other
channel activate that channel (pressing CH I or CH
II) causing DUAL mode. Then switch off the
previous channel by depressing the respective
channel pushbutton. In combination with internal
triggering the triggersource follows the mono
channel setting. For algebr. addition depress CH
and CH II simultaneously (ADD LED lit). Depressing
both pushbuttons simultaneously again reverts to
the previous setting.

TRIG. Triggersource selection in internal trigger mode.
(pushbutton Depressing in DUAL mode causes the switch over
+ LED‘s) from trigger source channel I (TR I) to trigger source

channel II (TR II) and reverse. Depressing the
pushbutton untilboth TR I and TR II LED‘s lit,
switches over to alternate triggering if DUAL mode
is active. Depress again to quit alternate triggering.
Not available in combination with ext. triggering, XY
or COMP . TESTER modes.

INPUT CH II Channel II signal input.
(BNC connector)

Input impedance 1MΩ II 20pF .

AC-DC Selects input coupling of CH. II vertical amplifier.
(pushbutton + DC = direct coupling (LED lit)
„DC“ LED) AC = coupling via capacitor (LED dark).

GD GD (LED lit) = signal disconnected from input,
(pushbutton Y amplifier input grounded.
+ LED)

VOLTS/DIV. Channel II input attenuator. <> pushbuttons select
(pushbuttons Y input sensitivity in mV/div. or V/div. in 1-2-5
+ LED scale) sequence. Deflection coefficient LED blinking =

uncalibrated.

VAR. 2.5:1 Fine adjustment of Y amplitude (knob) CH.II.

Increases attenuation factor min. by 2.5 (left hand
stop). For amplitude measurement must be in CAL.
position (right hand stop).

EXT Pushbutton selects between internal and external
(pushbutton trigger source. If the EXT LED lights the trigger
+LED) signal originates from the TRIG. INP. socket (44).

Y-POS.II Controls vertical position of channel II display.
(knob)

INV Inversion of CH. II (display LED lit) and reverse.
(pushbutton and reverse. In combination with ADD button =
+LED) difference CH. II CH. I.

TRIG. INP . External triggersignal input.
(BNC-connector)

Active if the EXT LED lit.

Subject to change without notice

60 MHz

HM604-3

Ω

Ω

31

32

Subject to change without notice