Hameg HM 103-2 User manual

Instruments

Table of contents
Technical Data PI
Accessories Z1
Operating instructions
General Information Ml
Warranty Ml
Safety Ml
Operating Conditions M2
Use of Tilt Handle M2
First Time Operation M2
Probe Adjustment M3
Type of Signal M4
Amplitude Measurement M4
Time Measurement M5
Connection of Test Signal M6
Triggering and Timebase M7
X-Y Operation M8
Component Tester M9
Maintenance M10
Accessories M10
Test patterns (Component Tester) Mil
Short Instruction
and Front View K1
Test Instructions
General T1
Cathode-Ray Tube: Brightness and Focus,
Linearity, Raster Distortions T1
Astigmatism Check T1
Symmetry and Drift of the Vertical Amplifier ....T1
Calibration of the Vertical Amplifier T1
Transmission Performance
of the Vertical Amplifier T2
Triggering Checks T2
Timebase T3
X-Y Operation T3
Component Tester T3
Trace Alignment T3
Power Voltage Fluctuations T3
Service instructions
General SI
Mains/Line Voltage Change SI
Instrument Case Removal SI
Operating Voltages SI
Maximum and Minimum Brightness S2
Astigmatism Correction S2
Trigger Threshold S2
Trouble-Shooting the Instrument S2
Replacement of Components and Parts S3
Replacement of the Power Transformer S3
Adjustments S4
Oscilloscope
HM 103-2
Circuit Diagrams
Block Diagram S21
Power Supply, CRT, Unblanking,
Calibrator, Trace Rotation,
Component Locations TB-Board S22
Y-Input, Attenuator, Y-Preamplifier,
Trigger Pickoff S23
Component Locations YP-Board, Yl-Board S24
Y-Final Amplifier, Comp. Locations Y-Final Ampl. ..S24
Trigger Circuit, Comparator,
Timebase, X-Amplifier,
X-Final Amplifier, CT-Y-Preamplifier S25
Component Locations Main-Board S26
Component Locations FC-Board S26
Identification of Electrical Components S27
Adjusting Plan A1
Subject to change without notice 4.91 •103-2

OSCILLOSCOPE HM103-2
Specification
Vertical Deflection
Bandwidth: DC to 10MHz (-3dB),
AC to 15 MHz j-6dBI.
Risetime; approx. 35ns.
Overshoot: maximum 1%.
Deflection coefficient: 10 calibrated steps,
5mV/div. to 5V/div. in 1-2-5 sequence. ±3%.
variable control 1:2.5 to at least 12.5V/div.
YMAG.xS (calibrated) to 1mV/div. ±5%,
(frequency range DC to 3.5MHz, —3dB).
Input impedance; 1MQ II 25pF.
Input coupling; DC-AC-GND.
Input voltage; max. 400V (DC -h peak AC).
Trigger System
Automatic or normal
with manual level control.
Bandwidth; 2Hz up to at least 30 MHz.
Slope; px)sitive or negative.
Source: internal or external (BNC connector).
Coupling; AC. TV (frame) low-pass filter.
Threshold; internal 0.5div., external 0.4V.
Horizontal Deflection
Time coefficients; 18 calibrated steps.
0.2ns/div. to 01 s/div. in 1-2-5 sequence,
variable control 2.5:1 to min. 0.25 s/div.
Accuracy in calibrated position: ±5%.
Normal length of sweep line: approx lOdiv.
Bandwidth X-Ampi.; 2Hz to approx. 850kHz
Deflection coefficient; approx 045V/div.
Input; BNC connector (on front panel).
X-Y phase shift: <3* up to 70kHz
Component Tester
Test voKage; max. 7.5V rms (open circuit).
Test current: max. 23mA rms (shorted).
Test frequency. 50- 60 Hz (line frequency).
Test connection: 2banana jacks 4mm dia
One test lead is grounded (Safety Earth)
General Information
Cathode-ray tube; ER 100 (P43 phosphor),
rectangular screen, internal graticule 8x lOdiv.
Accelerating potential: 1950V.
Trace rotation: adjustable on front panel.
Calibrator, square-wave generator approx. 1kHz
for probe compensation and Ycalibration;
output (on front panel): 0.2V ±1 %.
Electronic regulation for all important
supply voltages including high voltage.
Protective system* Safety Class I(lEC 348)
Line voltages: 110, 125, 220, 240V AC.
Permissible line fluctuation: ±10%.
Line frequency range; 50 to 60 Hz.
Power consumption: approx. 21 Watt.
Weight: approx. 3.7 kg.
Cabinet (mm). W212. H114, D280.
Colour: techno-brown.
Lockable tilt handle
Subject to change.
Test Displays
using the Component Tester
Transistor Diode
10 MHz Compact-Oscilloscope
1Channel, max, 1mV/div. Sensitivity
Timebase: 0.25 s/div. to 0.2)is/div., triggering up to 30 MHz;
Built-in Component Tester.
The compact HM 103-2 was developed specifically for field service, tech-
nical vocational schools and the advanced hobbyist. It has an impressive
1mV/div. vertical input sensitivity, and input signals as small as 0.5div. are
enough to trigger the timebase at frequencies up to 30 MHz The HM 103-2 of-
fers the user two trigger modes: Automatic or Normal. In the Normal mode,
triggering is controlled by the Level control. ATV low-pass filter is astandard
feature, which permits the display of video signals at the frame frequency.
Acomponent tester is also provided as astandard feature of the
HM 103-2. This allows the user to perform quick tests of electronic compo-
nents including resistors, diodes, ICs, capacitors, inductors, and transistors,
either in or out of circuit. Asingle pushbutton switches from oscilloscope oper-
ation to component tester mode,
Abright, sharply-focused, fully-shielded CRT with internal graticule
ensures parallax-free viewing -essential for avariety of maintenance and
monitoring tasks. All critical supply voltages are electronically regulated. The
display will remain stable even under conditions of wide-range voltage fluctu-
ations. A0.2 Vsquarewave signal is provided at the front panel for setting
probe compensation and checking vertical gain calibration.
The HM 103-2 offers exceptional feature content for a10 MHz oscillo-
scope. particularly in comparison with other oscilloscopes in this class. Com-
pact design, light weight, rugged construction, ease of operation and long-
term reliability make the HM 103-2 an indispensable instrument for shop, field
service, and school application.
Accessories supplied
10:1 Probe, Line cord. Operators Manual.

OSCILLOSCOPE ACCESSORIES
Test Cable Banana -BNC HZ32
Coaxial test cable; length 1.15 m, characteristic impedance 500.
Cable capacitance 120pF. Input voltage max 500Vp.
Modular Probes
The clear advantage over ordinary probes are field replaceable
parts and the HF-compensation feature on the 10:1 attenuator pro-
bes. For the first time, probes in this price range allow adjustments
of their HF-characteristics to match individually the input imped-
ance of each scope. This is particularly important for scopes with
higher bandwidths (>50MHz), as otherwise strong overshoot or
rounding may occur, when measuring fast-rising square waves.
An exact HF-compensation. however, is only possible with square-
wave generators having arisetime <5ns. Most HAMEG scopes
already feature such acalibration generator. For other oscillo-
scopes, it is available as accessory item HZ60-2. At present the
following Modular Probes are available (H236 without HF-com-
pensation):
Type HZ36
selectable
HZ51 HZ52 HZ53 HZ54
selectable
Attenuation Ratio 1:1/10:1 10:1 10;1(HF) 100:1 1:1/10:1
Bandwidth min (MHz) 10/ 100 150 250 150 10/150
Risetime (ns) 35/3.5 <2 <14 <2 35/<2
Inp. Capacitance (pF) 47/18 16 16 6,5 40/18
Inp Resistance (Mil) 1/10 10 10 100 1/10
Inp Voltage max (Vp) 600 600 600 1200 600
Cable Lertgth (m) 1.5 1.2 1.5 1.5 1.2
Spare Cable for HZ36 HZ39
Spare Cable for HZ51. HZ 54 HZ57
Sparepan Kit (2 sprung hooks, 2screw tips, 1ground cable) HZ40
Demodulator Probe HZ55
Special probe for AM-demodulation and wobbulator measure-
ments. HF-Bandwidth 100kHz- 500MHz (±ldB). AC Input Volt-
age 250mV -50V,^g. DC Isolation Voltage 200V DC including
peak AC. Cable length 1.2m.
High Voltage Probe HZ58
For measurement of voltages up to 15kVpp. Input resistance
approx. 500mQ Recommended load resistance! MQ/10MQ
(switchable). Attenuation ratio 1000:1. Bandwidth 1MHz. Cable
length 1.5 m. BNC connector.
Test Cable BNC- BNC HZ34
Coaxial test cable; length 1m, characteristic impedance 5011.
Cable capacitance 126pF, Input voltage max. 500Vp.
Adapter Banana -BNC HZ20
Two 4mm binding posts (1 9mm between centers) to standard BNC
male plug. Input voltage max. 500Vp.
500 Through -Termination HZ22
For terminating systems with 50 Qcharacteristic impedance.
Maximum load 2W. Max. voltage lOV,^,.
Carrying Cases
For HM 103 HZ95
For HM203. HM204, HM205, HM208, HM408, HM604,
HM605 and HM 1005 HZ96
Viewing Hood HZ47
For HM203, HM204, HM205, HM208, HM408, HM604, HM605
and HM 1005
Scope-Tester HZ60-2
For Checking the Yamplifier, timebase. and compensation of all
probes, the HZ60 2is acrystal-controlled, fast rising (typ. 3ns)
square-wave generator with switchable frequencies of DC, 1-10-
100Hz, 1-10- 100kHz, and 1MHz. Three BNC outputs provide sig-
nals of 25mVppinto50Q, 0.25Vpp and 2.5 Vpp (open circuit for 1Ox and
lOOx probes); accuracy ±1%. Battery-powered.
Component-Tester HZ65
Indispensable for trouble-shooting in electronic circuits. Single
component and in-circuit tests are both possible. The HZ65 oper-
ates with all scopes, which can be switched to X-Y operation (ext.
horizontal deflection). Non-destructive tests can be carried out on
almost all semiconductors, resistors, capacitors, and coils. Two
sockets provide for quick testing of the 3junction areas in any small
power transistor. Other components are connected by using 2
banana jacks. Test leads supplied.
Examples of Test Displays:
Sf>ort circuit Capacitor 33mF Junction E-C Z-DKxJe<8V
Printed in West Germany 5^0 Z1

Operating Instructions
General Information
The new HM 103-2 is as easy to use as all HAMEG instru-
ments. Technologically it represents the latest state of en-
gineering in this price range. This is particularly illustrated by
the increased use of monolithic integrated circuits. The log-
ical arrangement of the controls and connectors on the front
panel ensures that the user will quickly become familiar
with the operation of the instrument. However, even ex-
perienced operators are advised to read the following in-
structions thoroughly, as they include important informa-
tion relating to the use of the HM 103-2.
The front panel is subdivided into three sections according
to the various functions. The INTENS. (intensity), FOCUS,
and TR (trace rotation) controls are arranged directly below
the screen of the cathode-ray tube (CRT). Also the calibrator
output (CAL. 0.2V) is located in this section.
The Y-Section, located on the right of the screen, contains
the red POWER pushbutton and indicating LED, the vertical
input BNC connector with its input coupling pushbutton
(AC/DC), the GD (ground) pushbutton, and the CT (Compo-
nent Tester) pushbutton with two banana jacks. Further-
more, the Y-Section contains the Y-AMPL. input attenuator
switch with its variable control, Y-POS. (position) control,
and the Y-MAG.x5 pushbutton.
All operating controls for TIMEBASE, triggering, and X-
POS. are arranged on the right side of the front panel in the
X-Section. This section contains five pushbuttons and two
input BNC connectors for external triggering and external
horizontal deflection.
The instrument is so designed that even incorrect operation
will not cause serious damage. The pushbuttons control
only minor functions, and it is recommended that before
commencement of operation all pushbuttons are in the
"out" position. After this the pusbuttons can be operated
depending upon the mode of operation required. For a bet-
ter understanding of these Operating Instructions the front
panel picture at the end of these instructions can be un-
folded for reference alongside the text.
The HM 103-2 accept all signals from DC (direct voltage) up
to afrequency of at least 10MHz (-3dB). For sinewave volt-
ages the upper frequency limit will be 20-25 MHz. How-
ever, in this higher frequency range the vertical display
height on the screen is limited to approx. 2div. In addition,
problems of time resolution also arise. For example, with
10 MHz and the fastest adjustable sweep rate (200ns/div.),
one cycle will be displayed every O.Bdiv. The tolerance on
indicated values amounts to ±3% in the vertical and ±5%
in the horizontal deflection direction. Ail values to be mea-
sured can therefore be determined reatively accurately.
However, from approximately 3MHz upwards the measur-
ing error will increase as aresult of loss of gain. At 8 MHz
this reduction is about 10%. Thus, approximately 11%
should be added to the measured voltage at this frequency.
As the bandwidth of the amplifiers differ (normally between
10 and 15 MHz), the measured values in the upper limit
range cannot be dffined exactly. Additionally, as already
mentioned, for frequencies above 10MHz 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.
Warranty
Before being shipped each instrument must pass a10hour
quality control test. Almost every early failure can be de-
tected by means of intermittent operation during this test.
Nevertheless, acomponent may fail but only after alonger
period of operation. Therefore, all HAMEG instruments
are under warranty for aperiod of two years, provided
that the instrument has not undergone any modifications.
HAMEG will repair or replace products which prove to be
defective during the warranty period. No other warranty is
expressed or implied. HAMEG is not liable for consequen-
tial damages. It is recommended that the instrument be re-
packaged in the original manner for maximum protection.
We regret that transportation damage due to poor packag-
ing is not covered by this warranty.
In case of any complaint, attach atag to the instrument with
adescription of the fault observed. Please supply name and
department, address and telephone numberto ensure rapid
service.
Safety
This instrument is designed and tested according to interna-
tional safety standards (e.g. IEC348: Safetyrequirements
for electric measuring apparatus). The instrument has
left the factory in perfect safety condition. To preserve this
state and to ensure operation without danger, the user
must observe all advises and warning remarks in these
Operating, Test, and Service Instructions. The case, chas-
sis, and all measuring terminals are connected to the
Safety Earth conductor. The specification of the instru-
ment corresponds to Safety Class I(three-conductor AC
power cable). The grounded accessible metal parts (case,
sockets, jacks) and the power line circuit of the HM 103-2 are
tested against one another with 2000V50 Hz. Under certain
conditions, 50 Hz or 60 Hz hum voltages can occur in the
Printed in Germany (1991) Ml 103-2

measuring circuit due to interconnection with other mains/
line powered instruments or devices. This can be avoided
by using aprotective isolating transformer between the
mains/line outlet and power plug of the HM 103-2. Without
an isolating transformer, the instrument's power cable
must be plugged into an approved three-contact electrical
outlet, which meets International Electrotechnical Commis-
sion (lEC) safety standards.
Warning!
Any interruption of the protective conductor inside or
outside the instrument or disconnection of the protec-
tive earth terminal is likely to make the instrument
dangerous. Intentional interruption is prohibited.
If aprotective isolating transformer is used for the dis-
play of signals with high zero potential, it should be
noted that these voltages are also connected to the os-
cilloscope's case andotheraccessible metalparts. Volt-
ages up to 42 Vare not dangerous. Higher voltages,
however, involve ashock hazard. In this case, special
safety measures mustbe taken andmustbesupervised
by qualified personnel.
As with most electron tubes, the cathode-ray tube develops
X-rays. With the HM 103-2 the dose equivalent rate falls
far below the maximum permissible value of36pA/kg.
Operating Conditions
Admissible ambient temperature range during operation:
-M0°C... -I-40°C. Admissible ambient temperature range
for storage or transportation: -40°C... -t-70°C. If con-
densed water exists in the instrument it should not be
turned on before acclimatization is achieved. In some cases
(an extremely cold oscilloscope) about two hours should be
allowed before putting the instrument into operation. The
instrument should be placed in aclean and dry room. In
other words, the instrurhent may not be put into operation
in explosive, corrosive, dusty, or moist environments. The
instrument may be operated in any position, however, the
convection cooling must not be impaired. Therefore, when
the instrument is in continuous operation it should be used
in the horizontal position preferably on its tilt stand.
-after along storage under unfavourable
circumstances (e. g. out of doors or in moist
environments),
-after excessive transportation stress (e. g. in poor
packaging).
Use of the Tilt Handle
The handle of the oscilloscope can be fixed in three posi-
tions, one for use as acarrying handle and two positions as
atilt stand. With the tilt handle the instrument can be in-
clined 12° or 24° to the horizontal.
Handling is as follows:
-Place the HM 103-2 on its rear feet. The front drop-in
pins in the hinges will fall back into the front groove of
the notched discs (fixed on the cabinet).
-Pull the handle only about 5mm out of its locking posi-
tion and turn it towards the lower edge of the front panel.
—Lock the handle into the required position by pushing it
back towards the hinges.
—Place the instrument in its work area.
[
tl [T
Handle in carrying position
First Tims Operation
Check that the instrument is set to the correct mains/
tine voltage.
The instrument must be disconnected and secured against
unintentional operation if there is any presumption that safe
operation is not possible. This supposition is qualified
-if the instrument has visible damage,
-if the instrument has loose parts,
-if the instrument does not function.
On delivery, the instrument is set to AC 220V ±10% (50-
60 Hz) mains/line voltage. The power plug-in unit at the rear
contains the three-pin power connector. For this athree
wire power cord with triple-contact connector and three-
pole power plug is required. The appliance inlet also con-
tains the power fuse, whis is interchangeable for the diffe-
rent mains/line voltages. The fuse holder with its square top
M2 103-2

plate can be pulled out, and changing of the mains/line
voltage is possible by turning this plate 90 degrees for each
of the four voltages marked on the plate. The fuse holder
should then be plugged in again in the desired position (see
triangle), which should be the closest value of the mea-
sured mains/line voltage In our area. The set value is al-
ways readable. The power fuse must correspond to the
voltage selected and when necessary should be replaced.
The type and rated current are given on the rear panel and
in the Service Instructions.
Before applying power to the oscilloscope, it is recom-
mended that the following simple procedures are per-
formed:
-Check that all pushbuttons are in the out position, i.e. re-
leased.
-Rotate the two variable controls with arrows, i.e.
TIMEBASE variable control and Y-AMPL. attenuator
variable control, fully clockwise in their calibrated detent.
-Set the control knobs with marker lines to their midrange
position (marker lines pointing vertically).
-The AT/NORM, pushbutton in the X-Section should be
in out position (AT).
-The GD button in the Y-Section should be depressed.
the orientation ofthe oscilloscope on the place ofwork.
Acentered trace may not align exactly with the hori-
zontal centerline ofthe graticule. Afewdegrees ofmis-
alignment can be corrected byapotentiometeraccessi-
ble through an opening on the front panel markedTR.
Probe Adjustment
To achieve the undistorted display of signals when using an
X10or X100 attenuator probe, the probe must be compen-
sated to match the input impedance of the vertical
amplifier. This can be easily achieved as the HM 103-2 has
abuilt-in square-wave generator with arepetition frequency
of approx. 1kHz and an output voltage of0.2Vpp ±1%.
The method employed is as follows. The probe tip with its
sprung hook is connected to the output eyelet designated
by CAL. (calibrator) on the front panel of the instrument. The
probe trimmer is then adjusted by using the trimming tool
supplied. The correct display is shown in the following fi-
gure.
Switch on the oscilloscope by depressing the red POWER
pushbutton. An LED will illuminate to indicate the working
order. The trace, displaying abaseline, should be visible
after ashort warm-up period of 30 seconds. Adjust Y-POS.
and X-POS. controls to center the baseline. Adjust IN-
TENS. (intensity) and FOCUS controls for medium bright-
ness and optimum sharpness of the trace. The oscilloscope
is now ready for use.
r~ r~
r~
incorrect correct incorrect
If only aspot appears (CAUTION! CRT phosphor can be
damaged.), reduce the intensity immediately and check
that the X-Y pushbutton is in the released (out) position. If
the trace is not visible, check the correct positions of all
knobs and switches (particularly AT/NORM, button in out
position).
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 asingle spot is dis-
played. as avery high intensity setting may cause damage
to the fluorescent screen of the CRT. Switching the oscillo-
scope off and on at short intervals stresses the cathode of
the CRT and should therefore be avoided.
In spite of Mumetal-shielding of the CRT, effects of the
earth's magnetic field on the horizontal trace position
cannot be completely avoided. This is dependent upon
The TIMEBASE switch should be in the 0.2ms/div. posi-
tion. The input coupling is set to DC (AC/DC button de-
pressed). If the attenuator sensitivity is set to 5mV/div.
(variable control to CAL.), the display will have aheight of
4div. when ax10 probe is being compensated. As aat-
tenuator probe is constantly subjected to considerable
stresses, the compensation should be frequently checked.
It should be noted that the frequency of the square-wave
generator is unsuitable for the time calibration. Further-
more, the pulse duty factor has not the 1:1 value. Finally,
the rise and fall times of the square signal are so fast that
the edges —even with maximum intensity -are visible
only with difficulty. This is not aflaw, but actually the pre-
condition for asimple and exact probe compensation (or a
deflection coefficient check) like horizontal pulse tops, cali-
brated pulse amplitude, and zero potential on the negative
pulse top.
M3 103-2

Type of Signal
All types of signals whose frequency spectrum is below
10MHz can be displayed on the HM 103-2. The display of
simple electrical processes such as sinusoidal RF and AF
signals or ripple poses no problems. However, when
square or pulse-shaped signals are displayed, it must be re-
membered that their harmonic content must also be
transmitted. In this case, the bandwidth on the vertical
amplifier must be considerably higher than the repetition
frequency of the signal. In view of this, accurate evaluation
of such signals with the HM 103-2 is only possible up to a
maximum repetition rate of 1MHz. Operating problems can
sometimes occur when composite signals are to be dis-
played, especially if they do not contain any suitable level
components and repetition frequency which can be used
for triggering. This occurs, for example, with burst signals.
To obtain astably triggered display in these cases, it may be
necessary to use Normal Triggering and/or TIMEBASE var-
iable control. Television video signals are relatively easy
to trigger. However, when investigating signals at frame
rate, the TV pushbutton in the X-Section has to be de-
pressed (low-pass filter). In this mode, the more rapid line
pulses are attenuated so that, with appropriate level adjust-
ment, triggering can easily be carried out on the leading or
trailing edge of the frame synchronizing pulse.
For optional operation as aDC or AC voltage amplifier, the
vertical input is provided with an AC/DC coupling switch.
The DC position should only be used with an attenuator
probe or at very low frequencies or if the determination of
DC voltage content of the signal is absolutely necessary.
However, when investigating very low-frequency pulses,
misleading ramp-offs may occur with AC coupling. In this
case, DC operation is to be preferred if the signal voltage is
not superimposed on atoo high DC voltage level. Other-
wise, acapacitor of adequate capacitance must be con-
nected before the input of the vertical amplifier (switched to
DC coupling). It should be remembered that this capacitor
must have asufficiently high breakdown voltage. DC opera-
tion is also recommended for the display of logic and pulse
signals, particularly if their pulse duty factor changes perma-
nently during operation. Otherwise, the display will move
up and down with any change. DC voltages can only be
measured in the DC position.
Amplitude Measurements
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 the signal waveform.
If asinusoidal 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 volt-
ages indicated in V^ms (Vetf) have 2.83 times the potential dif-
ference in Vpp. The relationship between the different volt-
age magnitudes can be seen from the following figure.
Voltage values of a sine curve
Vrms =effective value; Vp =simple peak or crest value;
Vpp =peak-to-peak value; V^om =momentary value.
The minimum signal voltage required at the vertical
amplifier input for adisplay of 1div. is ImVpp. This is
achieved with the Y-AMPL. attenuator control set at 5mV/
div., and its variable control in the fully clockwise posi-
tion, and the Y-MAG.x5 pushbutton depressed (in). How-
ever, smaller signals than this may also be displayed. The
deflection coefficients on the input attenuators are indi-
cated in mV/div. or V/div. (peak-to-peak value).
For exact amplitude measurements the variable con-
trol on the attenuator switch must be set to its calibra-
ted detent CAL.
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, afurther multiplica-
tion by afactor of 10 is required to ascertain the correct
voltage value.
With direct connection to the vertical input, signals up to
100Vpp may be displayed.
With the designations
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 quantity can be calculated from the two given
quantities:
U=DH H=^D=if
D H
M4 103-2

However, these three values are not freely selectable. They
have to be within the following limits (trigger threshold, ac-
curacy of reading):
Hbetween 0.3 and 8div., if possible 2.5 to 6div.,
Ubetween 1.5mVpp and 40Vpp,
Dbetween 5mV/div. and 5V/div. in 1-2-5 sequence.
Examples:
Set deflection coefficient D=50mV/div. ^0.05 V/div.,
observed display height H=4.6 div.,
required voltage U=0.05 -4.6 =0.23 Vpp.
Input voltage U=5Vpp,
set deflection coefficient D=1V/div.,
required display height H=5; 1=5div.
Signal voltage U=220 •2•V~2 =622 Vpp
(voltage >40Vpp, with probe x100 :U=6.22 Vpp),
desired display height H=min. 3.2div., max. 8div.,
max. deflection coefficient D=6.22 :3.2 =1.94 V/div.,
min. deflection coefficient D=6.22 :8=0.78V/div.,
adjusted deflection coefficient D=1V/div.
If the applied signal is superimposed on aDC (direct
voltage) level the total value (DC +peak value ofthe al-
ternating voltage) of the signal across the Y-input must
not exceed ±400 V. This same limit applies to normal at-
tenuator probes xIO, the attenuation ratio of which allows
signal voltages up to approximately 600V (DC-f- ACpeak) to
be evaluated. Voltages of up to approximately 1,200V
(DC -I- ACpeak) i^ay be measured by using the HZ53 high
voltage probe which has an attenuation ratio of 100:1. It
should be noted that its V^^s value is derated at higher fre-
quencies (see page M6: Connection of Test Signal). If anor-
mal X10probe 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 re-
sidual ripple of ahigh voltage is to be displayed on the oscil-
loscope, anormal x10probe is sufficient. In this case, an ap-
propriate high voltage capacitor (approx. 22-68 nF) must be
connected in series with the input tip of the probe.
It is very important that the oscilloscope input coupling is
set to DC, if an attenuator probe is used for voltages higher
than 400V (see page M6: Connection of Test Signal).
With input coupling switched to GD and with the Y-POS.
control, ahorizontal graticule line can be adjusted as arefer-
ence axis for ground potential. It can be placed under-
neath, on, or above the horizontal center line, as the case
may be to measure positive and/or negative deviations from
ground potential. Some switchable probes have abuilt-in re-
ference switch position for the same application.
Time Measurements
As arule, all signals to be displayed are periodically repeat-
ing processes and can also be designated as periods. The
number of periods per second is the recurrence frequency
or repetition rate. One or more signal periods or even part of
aperiod may be shown as afunction of the adjustment of
the TIMEBASE switch. The time coefficients on the
TIMEBASE switch are indicated in ms/div. and [xs/div.. Ac-
cordingly, the dial is subdivided into two sectors.
The duration ofasignalperiod or a portion ofthe wave-
form is ascertained by multiplying the relevant time
(horizontal distance in div.) by the time coefficient
selected on the TIMEBASE switch.
The time variable control (small knob on t/ie TIMEBASE
switch) must be in its calibrated detent (CAL.) for accu-
rate measurement (arrow horizontal and pointing to the
right).
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
:
T= LTc L=TTc =
F-11—
Tc
1
L
T—^
LTc FTc 'LF
However, these four values are not freely selectable.
They have to be within the following limits:
Lbetween 0.2 and lOdiv., if possible 1to lOdiv.,
Tbetween 0.1 fxs and 0.5 s,
Fbetween 2Hz and 10 MHz,
Tc between 0.2^s/div. and 0.1 s/div. in 1-2-5 sequence
Examples:
Displayed wavelength L=7div.,
set time coefficient Tc =0.5|xs/div.,
required period T=7•0.5 •10“® =3.5 jxs
required rec. freq. F=1:(3.5 -10“®) =286 kHz.
Signal period T=0.5s,
set time coefficient Tc =0.1 s/div.,
required wavelength L=0.5 :0.1 =5div.
Displayed ripple wavelength L=1div.,
set time coefficient Tc =10ms/div.,
required ripple freq. F=1:(1-10 -10“^) =100Hz.
M5 103-2

TV-line frequency F=15625 Hz,
set time coefficient Tg =lOpis/div.,
required wavelength L=1:(15 625-10 =6.4div..
Sine wavelength L=min. 2.8div., max. 7div.,
Frequency F=1kHz,
max. time coefficient Tc =1:(2.8-10^) =0.357 ms/div.,
min. time coefficient Tc =1:(7-10^) =0.1 43 ms/div.,
set time coefficient =0.2 ms/div.,
required wavelength L=1:(10^-0.2 -10~^) =5div..
ment. It is only important that the horizontal time distance is
measured between 10% and 90% of the pulse height and
that the time variable control is in the calibrated CAL. posi-
tion. For accuracy reasons, the display height should not be
too steep (too small sweep speed).
When very fast risetimes are being measured, the risetime
of the oscilloscope amplifier has to be deducted from the
measured time value. The risetime of the signal can be cal-
culated using the following formula.
When investigating pulse or square waveforms, the critical
feature is the risetime of the voitage 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.
Example: Apeak-to-peak pulse amplitude of Sdiv. vertical
height is symmetrically adjusted to the horizontal center
line using the Y-AMPL. switch and its variable control and
Y-POS. control. Use asweep speed setting that displays
one or max. three cycles (if possible) and be sure the
TIMEBASE variable control is in the calibrated detent. The
desired rising edge of the signal now intersects both the
—2div. (10%) and the -t-2div. (90%) horizontal graticule
line. Measure the horizontal distance in div. between
the 10% and 90% points and multiply this distance by
the setting of the time coefficient on the TIMEBASE
switch. Similarly, the falltime is measured between the
90% and 10% points on the trailing edge of the waveform.
The following figure shows correct positioning of the oscil-
loscope trace for accurate risetime measurement.
100%
90%
10%
0
With aset time coefficient on the TIMEBASE switch of
20 [xs/div., the example in the above figure would result in a
measured total risetime of
ttot =1-6div. •20|xs/div. =32^is
The above is, of course, only an example, as different set-
tings for the displayed pulse amplitude are possible. Note:
All settings in the Y-Section do not affect the time measure-
t=Vf2_4.2
r'•tot •osc
In this ttot is the total measured risetime, lose is the risetime
of the oscilloscope amplifier (approx. 35 ns with HM 103-2).
If ttot is greater than 250 ns, then t^t can be taken as the
risetime of the pulse, and calculation is unnecessary (error
smaller than 1%).
Connection of Test Signal
The signal to be displayed should be fed to the vertical input
of the oscilloscope by means of ashielded test cable, e.g.
the HZ32 or HZ34, or by ax10or x100 attenuator probe.
The use of these shielded cables with high impedance cir-
cuits is only recommended for relatively low frequencies
(up to approx. 50 kHz), for higher frequencies, and when the
signal source is of low impedance, acable of matched
characteristic impedance (usually 50 Q) is recommended.
In addition, and especially when investigating square
orpulse waveforms, aresistor equivalent to the charac-
teristic impedance ofthe cable must also be connected
to the cable directly at the input of the oscilloscope.
When using a50 Qcable, such as the HZ34, a50 Qthrough-
termination type HZ22 is available from HAMEG. When in-
vestigating square or pulse waveforms with fast risetimes,
transient phenomena on both the edge and top of the signal
may become visible if the correct termination is not used. It
must be remembered that the 50 Qthrough-termination
will only dissipate amaximum of 2watts. This power con-
sumption is reached with 10Vrms or with 28Vpp sine signal.
If aX10attenuator probe (e.g. HZ36) 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 attenuator probes, even high internal imped-
ance sources are only slightly beaded (by approximately
10MQ 1112 pF). Therefore, when the voltage loss due to the
attenuation of the probe can be compensated by ahigher
sensitivity setting on the HM 103-2, the probe should al-
ways be used. Also it should be remembered that the series
impedance of the probe provides acertain amount of pro-
tection for the input of the oscilloscope amplifier. It should
be noted that all attenuator probes must be compensated in
conjunction with the oscilloscope (see: Probe Adjustment,
page M3).
M6 103-2

If aX10 or X100 attenuator probe is used, the DC input
coupling must always be set. With AC coupling, the at-
tenuation is frequency-dependent, the pulses displayed can
exhibit ramp-off, DC-voltage contents are suppressed -
but loads the respective input coupling capacitor of the os-
cilloscope. The electric strength of which is maximum 400V
(DC +peak AC). For the suppression of unwanted DC volt-
ages, acapacitor of adequate capacitance and electric
strength may be connected before the input tip of the
probe (e.g. for ripple measurements).
Sometimes the trace will disappear after an input signal has
been applied. The attenuator switch must then be turned
back to the left, until the vertical signal height is only 2.4-
6div. with asignal amplitude greater than 40Vpp, an at-
tenuator probe must be inserted before the oscilloscope's
vertical input, if, after applying the signal, the trace is nearly
blanked, the period of the signal is probably substantially
longer than the set value on the TIMEBASE switch. It
should be turned to the left on an adequately greater time
coefficient.
With the FIZ53 xlOO probe, the permissible AC input volt-
age is frequency-dependent limited:
below20kHz (TV line frequency!) up to
max. 1,200 Vp ^2,400 Vpp ^851
above 20kHz (with fin MFIz) up to
Caution: When connecting unknown signals to the oscillo-
scope input, always use Automatic Triggering and set the
AC/DC input coupling to AC The Y-AMPL. attenuator
switch should initially be set to 5V/div..
212
fT Vp 424 „^150
It is important to remember that when low voltage signals
are being investigated the position of the ground point on
the test circuit can be critical. This ground point should al-
ways be located as close as possible to the measuring
point. If this is not done, serious signal deformation may re-
sult from any spurious currents through the ground leads or
test chassis parts. This comment also applies to the ground
leads on attenuator probes which ideally should be as short
and as thick as possible. For connection of a probe to aBNC
socket, aBNC-adapter should be used. It forms often apart
of the probe accessory. Grounding and matching problems
are then eliminated.
The location and quantitative measurement of amagnetic
leakage (e.g. from power transformer) into acircuit is possi-
ble using apick-up coil. If the coil has many windings, it
should be shielded against static fields (non-magetic shield
without short-circuited turn). Also the interconnection be-
tween coil and oscilloscope vertical input should be made
by ashielded cable with BNC male connector at one end. A
resistor of approx. 100 Qshould be connected in series be-
tween cable core and connector core. This resistor at-
tenuates radio-frequency excitation. The shieldings prevent
any undesired capacitive couplings.
Flum or interference voltage appearing in the measuring cir-
cuit (especially with asmall deflection coefficient) is possi-
bly caused by multiple grounding, because equalizing cur-
rents can flow in the shielding of the measuring cables (volt-
age drop between non-fused earthed conductors of other
line powered devices, which are connected to the oscillo-
scope or test object, e.g. signal generators with anti-inter-
ference capacitors).
Triggering and Timebase
In order to obtain asatisfactory stable display, the timebase
must be triggered synchronously with the test signal. The
trigger signal can be derived from the test signal itself,
when internal triggering is selected, or from afrequency re-
lated signal applied to the external trigger input. Note that
the trigger voltage is always AC coupled.
If the AT/NORM, pushbutton in the X-Section is in the out
position AT(Automatic Triggering), the sweep generator
will be triggered automatically. In the AT position and with
proper trigger control settings, the sweep can be started by
virtually all uncomplicated signals with repetition rates
above about 30 FIz and within the frequency range selected
by the trigger coupling switch, provided that the displayed
signal height is at least 0.5div. (trigger threshold for internal
triggering). In the absence of an adequate trigger signal or
when the trigger controls are misadjusted, the sweep free-
runs and produces abaseline (time axis) as areference
trace. Automatic Triggering takes place without operat-
ing the LEVEL control. The trigger mode operates in princi-
ple also with external triggering via the TRIG. EXT. connec-
tor. However, the (synchronous) trigger voltage required for
it should be approximately in the 0.4-4Vpp range.
With Normal Triggering (AT/NORM, button depressed)
and LEVEL adjustment, the sweep can be started by sig-
nals within the frequency range from 2Hz up to 30 MHz. In
the absence of an adequate trigger signal or when the trig-
ger controls (particularly the LEVEL control) are misad-
justed, no trace is visible, i.e. the screen is blanked com-
pletely. When using the internal Normal Triggering mode, it
is possible to trigger at any amplitude point of asignal edge,
even with very complex signal shapes, by adjusting the
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 LEVEL adjustment needs to be oper-
M7 103-2

ated with asensitive touch. In the external Normal Trigger-
ing mode, the same applies to the external trigger voltage
amplitude.
Triggering can be selected on either the rising or falling
edge of the trigger signal depending on whether the +/—
slope pushbutton is in the out or in position. In the out posi-
tion, triggering from the positive-going edge is selected.
The correct slope setting is important in obtaining adisplay
when only aportion of acycle is being displayed.
For external triggering, the TRIG. EXT. pushbutton in the
X-Section must be depressed. The sync, signal (0.4-4Vpp)
must then be fed to the TRIG. EXT. input connector.
In the TVcoupling mode, alow-pass filter is switched into
the trigger circuit. This filter cuts off any amplifier noise and
the frequency range above 1kHz of the trigger signal.
If the video signal of atelevision set is to be displayed at
frame frequency, triggering is generally difficult due to the
presence of the higher line frequency pulses can be at-
tenuated by depressing the TV pushbutton in the X-Section.
With Normal Triggering and correct setting of the +/-
slope button, it will now be found that the trigger LEVEL con-
trol can be adjusted to trigger from either the leading or trail-
ing edge of the frame pulse. This setting is advantageous for
triggering from other signals that have arecurrence fre-
quency of 800 Hz or less, as high frequency harmonics or
noise in the signal are suppressed by the presence of the low-
pass filter. However, TVtriggering at line frequency needs
AC coupling (TV button in out position). In both cases, always
Normal Triggering \N\th LEVEL adjustment should be used.
As already mentioned, simple signals may be triggered au-
tomatically in the automatic trigger mode (AT/NORM, button
in out position). The repetition rate may also vary in such
cases. However, if the pulse duty factor on square-wave or
pulse signals changes drastically or deforms to aneedle
pulse, the Normal Triggering mode with LEVEL adjustment
may well become necessary. With composite signals, the
trigger facility is dependent on the occurrence of certain
periodically recurring levels. The LEVEL adjustment of these
signals will require some care.
If it is found that atrigger point cannot be located on ex-
tremely complex signals even after repeated and careful ad-
justment of the LEVEL control in the Normal Triggering
mode, astable display may be obtained using the TIMEBASE
variable control.
The time coefficient settings on the TIMEBASE switch are
calibrated when the variable control (small knob on the
TIMEBASE switch) is set in the CAL. position. When this
control is set fully counter clockwise, the sweep speed is
decreased by afactor of at least 2.5. This factor is not pre-
cisely calibrated. When both the TIMEBASE switch and its
variable control are set fully counter clockwise, aminimum
sweep rate of approximately 0.25s/div. is obtained. The
choice of the optimum time coefficient depends on the re-
petition rate of the signal being measured. The number of
cycles displayed will increase with the time coefficient (by
turning the TIMEBASE switch counterclockwise).
X-Y Operation
For X-Y operation, the HOR. EXT. pushbutton has to be de-
pressed. The Xsignal must then be fed to the HOR. EXT.
input. The sensitivity of the Xamplifier is not adjustable. It is
approximately 0.45Vpp/div. Therefore, the maximum per-
missible voltage on this connector should not exceed
4.5Vpp. Higher voltages should be attenuated before con-
necting. The horizontal input is capacitively coupled; there-
fore, only AC voltages can be used for external horizontal
deflection. The bandwidth of the Xamplifier ranges from
2Hz to 850 kHz (-3dB). It should be noted that there is an in-
crease in phase difference between Xand Yabove 20 kHz,
which exceeds 3° at approx. 70 kHz.
if the voltages applied to the Xand Yinput connectors fail,
abright spot is displayed on the screen. With too high inten-
sity setting, this spot may cause phosphor burning, giving a
permanent loss of efficiency or, in extreme cases, com-
plete damage of the phosphor at this point.
In the X-Y operation mode, Lissajous figures can be used for
phase comparison between two signals of the same fre-
quency or for comparison of two signals with different fre-
quencies.
Examples of Lissajous figures:
Two sine signals of the same frequency (and amplitude)
with different phase angles.
Calculation of the phase angle (independent of both deflec-
tion amplitudes)
sin (p =I
cos q) -yr
a
q) =arc sin g
M8 103-2

Component Tester
General
The HM 103-2 has abuilt-in electronic Component Tester (ab-
breviated C7), which is used for instant display of atest pat-
tern to indicate whether or not components are faulty. The CT
can be used for quick checks of semiconductors (e.g. diodes
and transistors), resistors, capacitors, and inductors. Certain
tests can also be made to integrated circuits. All these com-
ponents can be tested in and out of circuit.
The test principle is fascinatingly simple. The power
transformer of the HM 103-2 delivers asine voltage, which
is applied across the component under test and abuilt-in
fixed resistor. The sine voltage across the test object is
used for the horizontal deflection, and the voltage drop ac-
ross the resistor (i.e. current through test object) is used for
vertical deflection of the oscilloscope. The test pattern
shows acurrent-voltage characteristic of the test object.
Since this circuit operates with mains/line frequency (50 or
60 Hz) and avoltage of 8.5V max. (open circuit), the indicat-
ing range of the CTis limited. The impedance of the compo-
nent under test is limited to a range from 20Q to 4.7 kQ.
Below and above these values, the test pattern shows only
short-circuit or open-circuit. For the interpretation of the dis-
played test pattern, these limits should always be borne in
mind. However, most electronic components can normally
be tested without any restriction.
Using the Component Tester
The CTis switched on by depressing the CT pushbutton in
the Y-Section. This makes the vertical preamplifier and the
timebase generator inoperative. Ashortened 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 CTmode, the only controls which can be operated
are INTENS., FOCUS, and X-POS.. All other controls and set-
tings have no influence on the test operation.
For the component connection, two simple test leads with
4mm 0banana plugs, and with test prod, alligator clip or
sprung hook, are required. The test leads are connected to
the insulated CTsocket and the adjacent ground socket in
the Y-Section. The component can be connected to the test
leads either way round.
After use, to return the oscilloscope to normal operation, re-
lease the CT pushbutton.
Test Procedure
Caution! Do not test any component in live circuitry —
remove all grounds, power and signals connected to
the componentunder test. Setup Component Testeras
stated above. Connect test leads across component to
be tested. Observe oscilloscope display.
Test Pattern Displays
Page M11shows typical test patterns displayed by the var-
ious components under test.
-Open circuit is indicatedbyastraight horizontalline.
-Short circuit is shown by astraight vertical line.
Testing Resistors
If the test object has alinear ohmic resistance, both deflect-
ing voltages are in the same phase. The test pattern ex-
pected from aresistor is therefore asloping straight line.
The angle of slope is determined by the resistance of the re-
sistor 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 20Q to 4.7kQ can be approxi-
mately evaluated. The determination of actual values will
come with experience, or by direct comparison with acom-
ponent of aknown value.
Testing Capacitors and Inductors
Capacitors and inductors cause aphase difference between
current and voltage, and therefore between the Xand Yde-
flection, giving an ellipse-shaped display. The position and
opening width of the ellipse will vary according to the imped-
ance value (at 50 or 60 Hz) of the component under test.
Ahorizontal ellipse indicates ahigh impedance or arela-
tively small capacitance or arelatively high inductance.
Avertical ellipse indicates asmall impedance or arela-
tively large capacitance or arelatively small inductance.
Asloping ellipse means that the component has acon-
siderable ohmic resistance in addition to its reactance.
The values of capacitance of normal or electrolytic capacitors
from 0.1 \iF to 1000\iFcao be displayed and approximate val-
ues obtained. More precise measurement can be obtained in
asmaller range by comparing the capacitor under test with a
capacitor of known value. Inductive components (coils, trans-
formers) can also be tested. The determination of the value of
inductance needs some experience, because inductors have
usually ahigher ohmic series resistance. However, the im-
pedance value (at 50 or 60 Hz) of an inductor in the range from
20 Qto 4.7 kQ can easily be obtained or compared.
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 fi-
gures below.
The main characteristic displayed during semiconductor
testing is the voltage dependent knee caused by the junc-
tion changing from the conducting state to the non conduct-
ing state. It should be noted that both the forward and the
reverse characteristic are displayed simultaneously. This is
always atwo-terminal test, therefore testing of transistor
amplification is not possible, but testing of asingle junction
is easily and quickly possible. Since the CT test voltage
applied is only very low (max. 8.5Vrms)- 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 experi-
ence is most frequently needed.
M9 103-2

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 asmall portion of the knee is visible. Z-
diodes always show their forward knee and, up to approx.
10V, their Z-breakdown, forms asecond knee in the oppo-
site direction. AZ-breakdown voltage of more than 12Vcan
not be displayed.
I
I
Type:
Terminals:
Connections:
Normal Diode High Voltage Diode
Cathode-Anode Cathode-Anode
(CT-GD) (CT-GD)
Z-Diode12V
Cathode-Anode
(CT-GD)
The polarity of an unknown diode can be identified by com-
parison with aknown diode.
Testing Transistors
Three different tests can be made to transistors: base-emit-
ter, base-collector and emitter-collector. The resulting test
patterns are shown below.
The basic equivalent circuit of atransistor is aZ-diode be-
tween base and emitter and anormal diode with reverse po-
larity between base and collector in series connection.
There are three different test patterns:
III
N-P-N Transistor: |l || |i
I
Terminals:
Connections:
b-e
(CT-GD)
b-c
(CT-GD) (CT-GD)
P-N-P Transistor:
1
J'
1
1
1
1
ll
1r 1
'1
1
Terminals:
Connections:
b-e
(CT-GD) (C^D) (CT-GD)
For atransistor the figures b-e and b-c are important. The fi-
gure e-c can vary; but avertical line only shows short circuit
condition.
These transistor test patterns are valid in most cases, but
there are exceptions to the rule (e.g. Darlington, FETs). With
the CT, the distinction between aP-N-P to aN-P-N transis-
tor is discernible. In case of doubt, comparison with a
known type is helpful. It should be noted that the same
socket connection (CT or ground) for the same terminal is
then absolutely necessary. Aconnection inversion effects a
rotation of the test pattern by 180 degrees round about the
center point of the scope graticule.
Pay attention to the usual caution with single MOS-
components relating to static charge or frictional elec-
tricity!
In-Circuit Tests
Caution! During in-circuit tests make sure the circuit is
dead. No power from mains/line or battery and no sig-
nal inputs are permitted. Remove all ground connec-
tions including Safety Earth (pull out powerplug from
outlet). Remove all measuring cables including probes
between oscilloscope andcircuit under test. Otherwise
the connection of both CT test leads is not recom-
mended.
In-circuit tests are possible in many cases. However, they
are not so well-defined. This is caused by ashunt connec-
tion of real or complex impedances -especially if they are
of relatively low impedance at 50 or 60 Hz -to the compo-
nent 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 CTsocket avoiding hum distor-
tion of the test pattern.
Another way is atest pattern comparison to an identical cir-
cuit 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 ade-
fect can be determined quickly and easily. Possibly the de-
vice itself under test contains areference circuit (e.g. asec-
ond stereo channel, push-pull amplifier, symmetrical bridge
circuit), which is not defective.
The test patterns on page Mil show some typical displays
for in-circuit tests.
Maintenance
Within the context of maintenance, it is recommended that
the most important characteristics and criteria of the
HM 103-2 be periodically checked. The following Test In-
structions indicate only those tests, which can be per-
formed without the use of expensive ancillary instruments.
Accessories
Each HAMEG oscilloscope is supplied with an Instruction
Manual and a10: 1divider probe. However, awide range of
accessories, which include test cables and probes, are av-
ailable and should be ordered according to the particular ap-
plication.
M10 103-2

Test patterns
Single Components
Mains transformer prim.
Single Diodes
Z-diodeunder8V
Rectifier
Single Transistors
Resistor 51 OQ Junction B-C Junction B-E
Capacitor 33 Junction E-C FET
In-circuit Semiconductors
Z-diode beyond 12VDiode paraiieled by 680 Q2Diodes antiparaliel
Germanium diode
Thyristor G+ Atogether
Diode in series with 51
Q
B-E with 1(iF -i- 680 Q
B-E paraileied by 680 Q
Si-diode with 10|xF
Mil 103-2

TRCAL.
miMTENS.
oFOCUS
O
0.2 V
l-l«nEC3
OSCILLOSCOPE
HM 103-2

Short Instruction for HM 103-2
First Time Operation
Check mains/line voltage setting and fuse rating at appliance inlet on rear panel.
Connect the instrument to power outlet.
Depress POWER pushbutton. LED indicates operating condition.
Case, chassis, andall measuring connectors are connected to the SafetyEarth conductor (Safety Class 1).
No other button is depressed; ensure that AT/NORM, button in out position.
Adjust INTENS. control for average brightness.
Center trace on screen using X-POS. and Y-POS. controls.
Then focus trace using FOCUS control.
Trigger Modes
Automatic Triggerung: AT/NORM, pushbutton in out position. Trace always visible.
Normal Triggering: AT/NORM, button depressed. Trace visible when triggered.
Normal Triggering need manual operation of the LEVEL control.
Triggering from positive-going signal edge: +/—slope button in out position.
Triggering from negative-going signal edge: +/— s/ope depressed.
This is important when only aportion of acycle is being displayed.
Internal triggering: TRIG. EXT. button in out position.
External triggering: TRIG. EXT. button depressed. Input via TRIG. EXT. connector.
External trigger signal: 0.4-4 Vpp, time-related to vertical input signal.
The coupling mode for internal and external triggering is always ACcoupled.
Composite video triggered at frame rate: TV button depressed. Use Normal Triggering.
Composite video triggered at line rate: TV button in out position. Use Normal Triggering.
Measurement
Connect test signal to vertical input connector.
Compensate attenuator probe using CAL. square-wave signal.
Select AC or DC input coupling. (GD: Yamplifier is disconnected from input and grounded.)
Adjust required display heigth of signal with Y-AMPL. switch and variable control.
Select sweep speed with TIMEBASE switch and variable control.
Adjust trigger point with LEVEL control (only in Normal Trigger mode).
Calibrated amplitude measurement with Y-AMPL. The variable control must be in cal. position (CAL.).
Calibrated time measurement with TIMEBASE. The variable control must be in cal. position (CAL.).
X-Yoperation: HOR. EXT. button depressed. Xinput via HOR. EXT. connector.
Xdeflection coefficient: approx. 0.45Vpp/div. ACcoupling only.
Component Tester
Depress CT button. Connect component terminals to CTand ground jacks.
In-circuit test: The circuit under test must be disconnected from power, signals, and ground (earth).
Pull out power plug of the circuit under test. Remove all connections to HM 103-2 (cable, probe).
Then start testing.
K1 103-2

Test Instructions
General
These Test Instructions are intended as an aid for checking
the most important characteristics of the HM 103-2 at regu-
lar intervals without the need for expensive test equipment.
Resulting corrections and readjustments inside the instru-
ment, detected 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 Time Operation instructions, care should
be taken that all knobs with arrows are set to their calibrated
positions. None of the pushbuttons should be depressed;
ensure that AT/NORM, button is in out position, TIME/
DIV. switch in 50|is/div. and VOLTS/DIV. switch in 5mV/
div. position. It is recommended to switch on the instru-
ment for about 30 minutes prior to the commencement of
any check.
Cathode-Ray Tube: Brightness and Focus,
Linearity, Raster Distortions
Normally, the CRT of the HM 103-2 has very good bright-
ness. Any reduction of this brightness can only be judged
visually. However, decreased brightness may be the result
of reduced high voltage. This is easily recognized by the
greatly increased sensitivity of the vertical amplifier. The
control range for maximum and minimum brightness (inten-
sity) must be such that the beam just disappears before
reaching the left hand stop of the INTENS. control (particu-
larly when the X-Y button is depressed), while with the con-
trol 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.
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 afault in the regu-
lation circuitry for the high voltage supply. The presetting
pots for the high voltage circuit, minimum and maximum
intensity, are only accessible inside the instrument (see
Adjusting Plan and Service Instructions).
Acertain out-of-focus condition in the edge zone of the
screen must be accepted. It is limited by standards of the
CRT manufacturer. The same is valid for tolerances of the
orthogonality, the undeflected spot position, the non-linear-
ity 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 asquare-
wave 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 astig-
matism control is necessary. An alternative method is to
check the shape of the spot. Depress HOR. EXT. button in
the X-Section and depress GD button in the Y-Section. The
FOCUS control is then repeatedly varied around the
optimum focusing point. The shape of the spot (not its size),
whether round or oval or rectangular, must stay the same to
the right and left of the optimum focusing point. Apoten-
tiometer of lOOkQ (see Adjusting Plan) is provided inside
the instrument for the correction of astigmatism (see Ser-
vice Instructions). Acertain 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 stage of the amplifiers.
Acheck of the vertical amplifier symmetry is possible
by shifting the Y-POS. control. Asine-wave signal of 10-
100 kHz is applied to the amplifier input. When the Y-POS.
control is then turned fully in both directions from stop to
stop with adisplay height of approximately 8div.. the upper
and lower portions 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. Ten minutes 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 O.Sdiv. during the following
hour.
Fluctuations in drift are caused by offset current. The drift is
too high, if the vertical trace position drifts by more than
O.Sdiv. on turning the appropriate attenuator switch
through all 10 steps. Sometimes such effects occur after
long periods of operation.
Calibration of the Vertical Amplifier
Asquare-wave voltage of 200mVpp ±1% is present at the
output eyelet. If adirect connection is made between this
eyelet and the input of the vertical amplifier, the displayed
signal in the SOmV/div. position (variable control to CAL.)
should be 4div. high (DC input coupling). Maximum devia-
tions of 0.1 2div. (3%) are permissible. \i axIOprobe is con-
Subject to change without notice T1 103-2

nected between the output eyelet and Yinput, the same
display height should result in the 5mV/div. poisition. 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 coeffi-
cient set.
With variable control at the attenuator switch fully counter
clockwise, the input sensitivity is decreased at least by the
factor 2.5 in each position. In the 50mV/dlv. 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 genera-
tor with afast risetime (max. 5ns). The signal coaxial
cable (e.g. HZ34) must be terminated at the vertical input
of the oscilloscope with aresistor equal to the characteri-
stic impedance of the cable (e.g. with HZ22). Checks
should be made at 50 Hz, 500 kHz, 50 kHz, 50 kHz and
500 kHz, 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 aflat
top without ramp-off, spikes and glitches; no overshoot is
permitted, especially at 500 kHz and adisplay 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 operator's discretion whether this test is underta-
ken or not.
Of course, the quality of the transmission performance is
not only dependent on the vertical amplifier. The input
attenuators, located in the front of the amplifier, are fre-
quency-compensated in each position. Even small capa-
citive changes can reduce the transmission performance.
Faults of this kind are as arule most easily detected with a
square-wave signal with alow repetition rate (e.g. 1kHz). If
asuitable generator with max. output of lOVpp 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. Acompensated 2:1 series
attenuator \s 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 elec-
trical components required are a1MQ±1 %resistor and, in
parallel with it, atrimmer 3-1 5pF in parallel with approx.
20 pF. One side of this parallel circuit is connected directly
to the input connector of the vertical amplifier and the other
side is connected to the generator, if possible via alow-
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 cou-
pling; square tops exactly horizontal; no ramp-off is permit-
ted). This is achieved by adjusting the trimmer located in the
2:1 attenuator.
The shape ofthe square-wave should then be the same
in each input attenuator position.
Triggering Checks
The internal trigger threshold is important as it determines
the display height from which asignal will be stably dis-
played. It should be approx. 0.5 div. (frequency-depend-
ent) for the HM 103-2. An increased trigger sensitivity
creates the risk of response to the noise level in the trigger
circuit, especially when the sensitivity of the vertical input
is increased by pressing the Y-MAG.x5 pushbutton. 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 volt-
age between 50 Hz and 1MHz. The AT/NORM, button
should be in out position (Automatic Triggering). Follow-
ing this it should be ascertained whether the same trigger
sensitivity is also present with Normal Triggering (AT/
NORM, button depressed). In this trigger mode, aLEVEL
adjustment is necessary. The checks should show the
same trigger threshold with the same frequency. On
depressing the -F/— slope button, the start of the sweep
changes from the positive-going to the negative-going
edge of the trigger signal. For higher frequencies, trigger-
ing up to at least 30 MHz (sinewave) should be possible.
For external triggering (EXT. TRIG, pushbutton depressed),
the EXT. TRIG, input connector requires asignal voltage of
at least 0.4Vpp, which is in synchronism with the Yinput sig-
nal.
Checking of the internal TV triggering is possible with a
video signal of any given polarity. In the TV position only,
reliable triggering on frame rate is possible. However, trig-
gering on line (horizontal scanning) frequency is only possi-
ble with TV button in out position. If no video signal is avail-
able, the function of the TV position (low-pass filter) can be
checked using mains/line frequency or the built-in calibrator
signal. With amains/line frequency signal (50-60 Hz),
depressing of the TV button should have no effect in con-
trast, the minimum signal voltage required for reliable trig-
gering should be at least double, when the 1kHz calibration
signal is applied.
T2 103-2

Timebase
Before checking the timebase it should be ascertained that
the trace length is approx. 10div.. If not, it can be correc-
ted with the potentiometer for sweep amplitude (see Adju-
sting Plan). This adjustment should be made with theTIME-
BASE switch in amid-position (i.e. 50^s/div.). Prior to the
commencement of any check set the time variable control
to CAL This condition should be maintained until the varia-
tion ranges of these controls are checked.
Check that the sweep runs from the left to the right side
of the screen (TIMEBASE switch to lOOms/div.; X-POS.
control in mid-range). This check is only necessary after
changing the cathode-ray tube.
If aprecise 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
HM 103-2 is given as ±5%, but as arule it is considerably
better than this. For the simultaneous checking of timebase
linearity and accuracy at least 10 oscillations, i.e. 1cycle
every div., should always be displayed. For precise deter-
mination, set the peak of the first marker or cycle peak
exactly behind the first vertical graticule line using the X-
POS. control. Deviation tendencies can be noted after
some of the marker or cycle peaks.
The 20 and 10ms/div. ranges of the TIMEBASE switch can
be checked very precisely with line frequency {50Hz only).
On the 20ms/div. range acycle will be displayed every div.,
while on the lOms/div. range it will be every 2div.
If aprecise Time Mark Generator is used for checking. Nor-
mal Triggering (AT/NORM, button depressed) and LEVEL
control adjustment is recommended.
The following table shows which frequencies are required
for the particular ranges.
100 ms/div. -10 Hz 0.1 ms/div. -10 kHz
50 ms/div. -20 Hz 50 ^is/div. -20 kHz
20 ms/div. -50 Hz 20 [xs/div. -50 kHz
10 ms/div. -100 Hz 10 |xs/div. -100 kHz
5ms/div. -200 Hz 5|xs/div. -200 kHz
2ms/div. -500 Hz 2fxs/div. -500 kHz
1ms/div. -1kHz 1^.s/div. -1MHz
0. 5 ms/div. -2kHz 0.5 fxs/div. -2MHz
0.2ms/div. -5kHz 0.2 |xs/div. -5MHz
The time variable control range can also be checked. The
sweep speed becomes slower by turning this variable con-
trol counter clockwise to its left stop. Five cycles at least
every 2div. should be displayed measurement in the 50 ^s/
div. range).
X-Y Operation
The deflection coefficient of the horizontal amplifier is
approximately 0.45Vpp/div. This value can be checked with
the sine voltage of a1kHz generator. Adjust the output volt-
age on the generator to If fh© generator's output
voltage cannot be exactly determined, it should be mea-
sured using the vertical input of the oscilloscope and
adjusted (on the generator's voltage control) to the equiva-
lent value of about 4.5 Vpp. Note down this value. Next, con-
nect the generator to the X-Y connector and depress the
X-Y button. Ahorizontal straight of this line must appear on
the screen. In order to ascertain the horizontal deflection
coefficient, divide the measured peak-to-peak voltage by
the measured line length in div.
Component Tester
After depressing the CT button, ahorizontal straight line has
to appear immediately when the CT socket is open. The
length of this trace should be approx. 4div. (50Hz). After
short-circuiting both CTsockets, avertical straight line with
approx. 4div. height should be displayed. The above stated
measurements have some tolerances. They are dependent
among other things on the mains/line voltage and fre-
quency.
Trace Alignment
The CRT has an admissible angular deviation ±5° between
the Xdeflection plane D1-D2 and the horizontal center line
of the internal graticule. This deviation, due to tube produc-
tion tolerances (and only important after changing the CRT),
and also the influence of the earth's magnetic field, which is
dependent on the instrument's North orientation, are cor-
rected by means of the TR potentiometer. In general, the
trace rotation range is asymmetric. It should be checked,
whether the baseline can be adjusted somewhat sloping to
both sides round about the horizontal center line of the
graticule. Witht the HM 103-2 in its closed case, an angle of
rotation ±0.57° (0.1 div. difference in elevation per lOdiv.
graticule length) is sufficient for the compensation of the
earth's magnetic field.
Power Voltage Fluctuations
If avariable mains/line transformer is available, the charac-
teristics of the HM 103-2 on power voltage fluctuations of
±10%, referred to the voltage indicated by atriangle ()
above the fuse holder (rear panel), should be checked.
Under these conditions no variations should be detected on
the display in either the vertical or horizontal axis.
T3 103-2