TM 11-6625-3025-14/ET426-AA-MMA-010/E154 VII210/T.O. 33A1-8-902-1-1
(7) The position of the H bar elements is variable by use of the V POSITION control on the front panel.
Check that the control range changes position of the pattern slightly more than a distance equal to the
width between elements at all settings in the V SPACING control. Leave the V POSITION control set at
mid-range, because this control will vary the number of V bar elements since some elements may be
moved off the display when position is adjusted.
(8) The number of H bar elements generated in the vertical tv field is variable by use of the V SPACING
control at the front panel. Check that the control range provides a minimum of 10 or less elements and
a maximum of 18 or more elements. Most common scan rates include the same field and frame rates,
60 and 30 Hz respectively. Therefore, the number of H bar elements will be the same for many scan
rates. Set the control to display the number of H bar elements desired in the positions desired.
(9) Observe the video portion of the signal while turning the VIDEO LEVEL control from 0 to 10. Video
amplitude should vary from 0.0v to 1.0v peak-to-peak +0.10v. The sync and blanking portions of the
composite video signal should remain at the levels set in flat field.
(10) Set pattern switch to BLACK. Set oscilloscope sweep to 2 msec per division. Connect the oscilloscope
external sync input to V drive source. Compare oscilloscope display to figure 6-15. Return pattern
switch to WHITE.
Figure 6-15. Oscilloscope Display of the Typical H BAR Signal Waveform at Vertical Rate, Black Polarity
6-43
