Performance Tests
TDS 420A, TDS 430A & TDS 460A Service Manual
4-51
Adjust the sync pulse
amplitude for 0.6 divisions.
Figure 4- 19: Adjusting Sync Pulse Amplitude
c. Check for stable triggering against limits:
H Read the following definition: A stable trigger is one that is
consistent; that is, one that results in a uniform, regular display
triggered on the selected slope (positive or negative). This display
should not have its trigger point switching between opposite slopes,
nor should it “roll” across the screen. At horizontal scale settings
appropriate for viewing video waveforms, the TRIG’D light remains
constantly lit.
H Press TRIGGER MENU. Press the main menu button Type
twice — first to pop up its menu and then to toggle it to Video.
H Press the main menu button Class to pop up its menu. Press it again
as needed to toggle it to NTS C .
H Press the main menu button Scan to pop up its menu.
H Press the side menu button Odd. Center the display at mid screen.
H CHECK that a stable trigger is obtained with the last two lines of
TV field 2 and the beginning of TV field 1 displayed. (If the last line
is a full TV line duration (63.5 s), then it is the end of field 2 — see
waveform R1 in Figure 4--20.)
H Press the side menu button Even. Center the display at mid screen.
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