Performance Tests
4-52
TDS 420A, TDS 430A & TDS 460A Service Manual
H CHECK that a stable trigger is obtained with the last of TV field 1
and the beginning of TV field 2 displayed. (If the last line is ½ of a
TV line duration (31.75 s), then it is the end of field 1 — see
waveform R2 in Figure 4--20.)
H Press the side menu button All.
H Press the main menu button Mode and Holdoff. Then press the side
menu button Holdoff.
H Use the General Purpose knob to set the holdoff to 1.
R1 waveform: Note that two
full lines start the display
R2 waveform: Note that 1½
lines start the display
R3 and R4 waveforms: Note
that with non-interlaced,
both fields, scan mode,
CH 1 switches between the
R3 and R4 displays
Figure 4- 20: Measurement of Video Sensitivity
H Rotate the horizontal POSITION control clockwise to move the
ends of both fields to the center of the display.
H CHECK that a stable trigger is obtained while alternating between
field 1 and field 2. (If the last line is alternating between a full TV
line and ½ a line in duration (63.5 s and 31.75 s respectively),
then triggering is occurring on both fields — see waveforms R3 and
R4 in Figure 4 --20.)
d. Check delay by lines:
H Press the main-menu button Scan.
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