Probe Adjust - Contacts; Ext.trig/Z-Inp - Bnc Connector; Mode Buttons With Led - Hameg HM400 Handbuch

30 PROBE ADJUST – Contact
At this contact a square wave signal of 1 kHz or 1 MHz with a rise time
of < 5 ns and an output impedance of 50 Ω is available for the adjust-
ment of probes other than 1:1, the amplitude is appr. 0.2 V
adjustment purposes neither the frequency, nor the duty cycle nor the
exact amplitude are of concern.
The frequency of the square wave depends on the setting of the TIME/
DIV 15 selector: between 0.2 s/DIV and 100 μs/DIV the frequency will
be 1 kHz and between 50 μs/DIV to 100 ns/DIV it will be 1 MHz. See the
chapter „First time operation and initial settings and „Probe adjustment
and application."
PROBE ADJUST : This contact is the ground connection for the
probe.
31 EXT.TRIG/Z-INP – BNC connector
This is either the external trigger or the external intensity modulation
input . The input impedance is 1 MΩ II 15 pF. The ground of this con-
nector is connected to the chassis and thus to the mains safety earth.
By shortly pressing the Z-INP 28
be changed.
EXT.TRIG: This BNC connector is the external trigger input if the Z-INP
LED is extinguished. The trigger source is selected with the buttons
to 19 ; if external triggering is selected, the Z input will be automatically
disabled.
Z-INP: Z modulation is only possible if the Z-INP
It is not possible to combine Z modulation with either external triggering
or with the „Component Tester" function, selecting one of these will
disable the Z modulation. With 0 V at this input the trace intensity will
not be infl uenced, with 5 V TTL level the trace will be fully suppressed;
do not apply higher voltages.
32 MODE select buttons with LED
Selection of CH1, CH 2, DUAL, ADD, XY and Component Tester modes,
the active mode is indicated by the respective LED lighting up. Change of
modes just requires shortly pressing the button of the desired function.
The modes do not affect the trigger control status.
CH 1: This button has a dual function: it either selects single channel
1 operation or allows access to the settings memory 1. Single channel
CH 1 operation will automatically also select CH 1 as the trigger source
unless external or line triggering were selected, this will be indicated
by the trigger source button 16
VOLTS/DIV 14 knob will be preserved. All control elements belonging
to this channel will be activated.
CH 2: This button has a dual function: it either selects single channel 2
operation or allows access to the settings memory 2. Single channel
CH2 operation will automatically also select CH2 as the trigger source
unless external or line triggering were selected, this will be indicated
by the trigger source button 17
VOLTS/DIV 14 knob will be preserved. All control elements belonging
to this channel will be activated.
DUAL: This button has a dual function: it either selects the dual channel
mode or allows access to the settings memory 3. The trigger settings
existing before selecting DUAL mode remain valid unless they are
now changed intentionally. In DUAL mode the LED will light up. In dual
channel mode the channel switching may be alternated or chopped.
ADD: This button has a dual function: it either selects the ADD mode or
allows access to the settings memory 4. The trigger settings existing
before switching to ADD remain valid unless they are now changed in-
tentionally. The active ADD mode is indicated by the LED lighting up.
Addition of CH 1 and CH 2 mode:
In this mode the signals of channels 1 and 2 are algebraically added, if
CH 2 is inverted CH1 – CH 2 will be displayed. CH 2 – CH 1 is not available.
. For probe
pp
button the function of the input can
28
button is illuminated.
lighting up. The last function of the
lighting up. The last function of the
F u n c t i o n o f t h e c o n t r o l s
For a correct result the settings of the two VOLTS/DIV selectors must
be identical. The vertical position is now infl uenced by both Y position
controls. See the respective paragraph in the introductory part of this
manual for further information, because the use of this mode requires
much care in order to avoid false measurements!
XY: This button has a dual function: it either selects the XY mode or it al-
lows access to the settings memory 5. If XY is active, the LED will light up.
XY operation: In XY mode the following displays/indicators will be
turned off:
1. The time base speed display.
2. The displays/indicators of trigger source, slope, coupling, hold-
off time.
The existing trigger control settings before switching to XY are pre-
served, however.
Also all controls belonging to these displays/indicators will be disabled.
5
The POSITION 1 and the TRIGGER LEVEL
too. The X position will remain to be controlled by the X-POSITION
knob.
COMP: This button has a dual function: it either selects the COMPO-
NENT TESTER function or it allows access to the settings memory 6.
16 If COMPONENT TESTER mode is selected, the LED will light up. By
pressing any other button the COMPONENT TESTER will be disabled.
Operation of the COMPONENT TESTER
The button COMP alternates between scope and Component TESTER
operation; when returning to scope operation, the last settings will be
resumed. See also the chapter „Component Tester". In this mode the
following controls and LED indicators are important:
– ADJUST – / + buttons
3
TRACE
– X-POSITION knob
The test of electronic components is a two-pole measurement. The
unit to be tested is connected to the two contacts below the screen by
using 4 mm plugs
33 COMPONENT TESTER – 2 contacts for 4 mm plugs
The test leads from the unit under test are plugged in here, the left
contact is connected to the chassis und thus to the mains safety earth.
For DC or low frequency measurements it may be used as a ground
terminal.
CH I: 500 mV
Instruments
A N A L O G S C O P E
10 knobs are disabled,
2
, with their LEDs: INTENS, FOCUS, and
13
COMP . ±10 V
pp
∼ 50 Hz
TESTER
33
Subject to change without notice
13
1
32
POWER POWER
CH1 CH1
CH2 CH2
DUAL DUAL
ADD ADD
XY XY
COMP COMP
41