Tektronix TDS 420A, Service Manual, Page: 62 / 288

Operating Information
2- 14
TDS 420A, TDS 430A & TDS 460A Service Manual
More About the General Purpose Knob.
As you have just seen, the general purpose
knob is used to extend the number of choices available to a side menu button.
You can also assign the general purpose knob to control additional functions.
Some of these additional functions include:
H
Cursor positioning
H
Display intensities
H
Delay time
H
Number of events
H
Trigger position
H
Holdoff
H
Offset
H
Variable persistence
H
File system
In all cases, the menus are used to select the function to which the general
purpose knob is assigned. The following attributes apply to this knob:
H
Depending on the function it is assigned to control, the general purpose knob
varies numerical readouts, positions objects (cursors) on screen, or selects
between icon-label settings that show up in side-menu labels.
H
The general purpose knob has a readout area at the upper-right corner of the
screen. (See Figure 2--1.) This readout always reflects the name and value of
the function that the general purpose knob is currently controlling.
H
The general purpose knob is affected by the SHIFT button. Pressing shift
toggles the knob between its fine and coarse modes. Fine mode is used for
most adjustments; coarse mode is used to traverse large parts of the
adjustment range in less time.
H
Whenever the general purpose knob assignment is changed, a knob icon
appears immediately to the left of the general purpose knob readout to notify
you of the assignment change. The icon is removed as soon as you use the
general purpose knob to change the value of the function it is assigned to.
H
To assign the general purpose knob to control a function, display the menu
containing the function; then select the function. (Note that the general
purpose knob cannot control all functions.)