HP 54600B User's And Service Manual page 26

What happens if the oscilloscope loses trigger?
If Auto Level is the trigger mode, Auto flashes in the status line. If dc coupled,
the oscilloscope resets the trigger level to the center of the signal. If ac
coupled, the oscilloscope resets the trigger level to the middle of the screen.
(Every time you press the Auto Level softkey, the oscilloscope resets the trigger
level.)
If Auto is the trigger mode, Auto flashes in the status line and the oscilloscope
free runs.
If either Normal or TV is the trigger mode, the trigger setup flashes in the status
line.
Press
Slope/Coupling
A softkey menu appears on the display. If you selected Auto level,
Auto, Normal, or Single as a trigger mode, six softkey choices are
displayed. If you selected TV as a trigger source, five other softkey
choices are available.
Toggle each of the softkeys and notice which keys affect the status line.
On the HP 54600B and HP 54603B, external trigger is always dc
coupled. If you select ac coupling or low frequency reject, these
functions do not occur until you change the trigger source to channel
1, channel 2, or line.
Adjust the Holdoff knob and notice the change it makes to the
3
display.
Holdoff keeps the trigger from rearming for an amount of time that you set
with the Holdoff knob. Holdoff is often used to stabilize the complex
waveforms. The Holdoff range is from 200.0 ns to about 13.5 s. It is
displayed, for a short time, in inverse video near the bottom of the display.
The Oscilloscope at a Glance
To trigger the oscilloscope
.
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