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then our reasoning is right, and the IF amplifier
requires realignment.
If the poor response at 2
MHz
the tuner input is misadjusted, causing a bite on
only one channel. Other traps at the input of the
set could similarly be misadjusted or faulty.
If the V I T S response at the detector output is nor-
mal for all channels, the tourble will be in the video
amplifier.
Look for open peaking coils, off-value
resistors, solder bridges across foil patterns, etc.
With dual-trace oscilloscope operation, the signal
information on each vertical blanking interval can
be viewed separately without trace overlapping,
although
the
information
field.
Fig. 18 indicates the oscilloscope control
setting for viewing the alternate vertical blanking
intervals.
1. The color T V receiver on which the vertical in-
terval information is to be viewed must be set
to a station transmitting a color broadcast.
2. The control settings of Fig. 18 are these re-
quired to obtain a 2-Field vertical display on
C H 1 .
3. With the oscilloscope and the T V receiver
operating, connect the CH1 probe (set to
1 0 : 1 ) to video detector test point.
4. Set the S Y N C and S L O P E switches as follows:
A. If the sync and blanking pulses of the
observed video signal are positive, use the
TV, +
positions.
B. If
the
sync
negative, use the T V , — positions.
5. Adjust the sweep time V A R I A B L E control so
that 2 vertical fields are displayed on the os-
cilloscope screen.
6. Connect the C H 2 probe (set to 1 0 : 1) to the
video detector test point.
7. Set the M O D E switch to D U A L position.
8. Place the sweep time V A R I A B L E in the C A L
position.
9. Set the S W E E P T I M E / D I V control to the 0.1
ms position.
This expands the display by
increasing the sweep speed. The V I T S in-
formation will appear toward the right hand
portion of the expanded waveform displays.
The waveform information on each trace may
appear as shown in Fig. 16. Because there is
no provision for synchronizing the oscilloscope
display to either of the two
comprise a complete vertical frame, if cannot
be predicted which field display will appear on
the CH 1 or C H 2 display.
10. Pull the <> POSITION control outward to ob-
tain an additional X 5 magnification.
18
alternates with each
and blanking
pulses are
fields which
Rotate
the control in a counterclockwise direction
moving the traces to the left until the expand-
ed information appears a s shown in Fig. 16.
Because of the low repetition rate and the high
sweep speed combination, the brightness level
of the signal displays will be reduced.
1 1 . Once the C H 1 and C H 2 displays have been
identified as being either Field 1 or Field 2
V I T S intormation, the probe corresponding to
the waveform display which is to be used for
signal-tracing and troubleshooting can be used
and the remaining probe should be left at the
video detector test point to insure that the
sync signal is not interrupted.
signal is interrupted, the waveform displays
may be reversed because, a s previously ex-
plained, there
is no provision
cilloscope to identify either of the two vertical
fields which comprise a complete frame.
S I N G L E - C H A N N E L A P P L I C A T I O N S
introduction:
In addition to the dual-trace applications previously
outlined, there are, of course, many servicing and
laboratory applications where only single-trace or
single-channel operation of the oscilloscope is re-
quired. By setting the M O D E switch to C H 2 and
using the CH2 amplifier, many flexible operations
will be achieved; and, in addition, by placing the
CH2
switch
to
P U L L
waveform is obtained can be inverted in polarity if
desired by the operator.
Television Servicing:
A triggered sweep oscilloscope is advantageous in
servicing and aligning television receivers. This os-
cilloscope also includes in addition, several features
that were incorporated to make television servicing
easier and more comprehensive. These feature in-
clude:
* W i t h the S Y N C switch set to T V position, the
S W E E P T I M E / D I V control automatically selects
the T V vertical sync at sweep speeds appropriate
for viewing frames and horizontal sync at sweep
speeds appropriate for viewing lines.
• W i d e bandwidth for high resolution video and
high speed pulse presentation.
Single-trace Operation and Peak-to-peak
Voltage Readings:
For
general
troubleshooting
troubles in almost any electronic equipment, the
oscilloscope is an indispensable instrument.
provides a visual display of absence or presence of
If the sync
in the os-
INV
position
whatever
and
isolation
of
It
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