Instruction manual

Subject to change without notice
40
The correct slope of the sync pulse (front edge) must be
selected and a suitable time coefficient 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/main frequency triggering (50-60Hz) is
possible, when the input signal is time-related (multiple or
sub multiple) to the power line frequency ( ~ LED lights).
There is no trigger threshold visible in this trigger mode. Even
very small input signals are triggered stable (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.
Time base
Before checking the time base it should be ascertained that
the trace length is approx. 10div in all time ranges. 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 100ms/div). This check
is only necessary after changing the cathode-ray tube.
If a precise marker signal is not available for checking the Time
base time coefficients, then an accurate sine-wave generator
may be used. Its frequency tolerance should not be greater
than ±0.1%. The time base accuracy of the instrument is given
as ±3%, but it is considerably better than this. For the
simultaneous checking of time base 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
and LEVEL control adjustment is recommended.
The signal frequency required for each time coefficient setting
can be determined easily by the aid of the readout. In time
measurement condition the distance of the vertical cursor lines
must be set to exactly 1 div. Then both readout information
regarding the time deflection coefficient and the time difference
show exactly the same value. After switching over from time
to frequency measurement, the readout displays the required
signal frequency in each time base setting.
Hold Off time (Analog)
The variation of the hold off time setting can not be measured
without opening the instrument. However, a visual check can
be made if the instrument is operated in A time base mode.
Without an input signal, set time base to 50ns/div, use
automatic peak (value) triggering. With minimum hold off time
the trace should be bright. It should noticeably darken if the
hold off time is increased to the maximum.
Component Tester
After selecting component tester mode, a horizontal straight
line should appear immediately, when the test leads are not
connected (open circuit). The length of this trace should be
approx. 8div. With the test leads shorted together, 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 also the influence of the earth‘s magnetic
field, which is dependent on the instruments North
orientation, are corrected by means of the TR potentiometer
(front panel).
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 instrument 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 earth‘s magnetic field.
Adjustments
1. Y AMP
(amplifier channel I and II field eddect transistors operating
points, invert and variable gain balance)
2. TRIGGER AMP
(trigger amplifier channel I and II DC operating points and
trigger threshold)
3. STORE AMP
(adaptation of the storage display to the analog display)
Attention!
During the automatic adjustment procedure no signal
may be applied to any input.
Information for calling calibration functions is given in PRINT
/ MENU (40) section Controls and Readout.
The new adjustment values are always present after the
instrument is switched on.
Note!
The automatic adjustment should only be made if
the instrument’s warm up time has passed and no
faults such as incorrect operating voltages are
present. During the automatic adjustment procedures
the readout indicates “Working”.
RS232 Interface - Remote Control
Safety
Caution:
All terminals of the RS232 interface are galvanically
connected with the oscilloscope and subsequently
with protective (safety) earth potential.
Measurement on a high level reference potential is not
permitted and endangers operator, oscilloscope, interface and
peripheral devices.
Test Instructions RS232 Interface - Remote Control