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Performance Tests
4–46
TDS 684A, TDS 744A, & TDS 784A Service Manual
b. Set the trigger mode: Press TRIGGER MENU. Now press the
main-menu button Mode & Holdoff; then press the side-menu button
Normal.
c. Set upper and lower limits that ensure triggering: See Figure 4–14.
H Press the main-menu button Type; then repeatedly press the same
button until Pulse is highlighted in the menu that pops up.
H Press the main-menu button Class; then repeatedly press the same
button until Width is highlighted in the menu that pops up.
H Press the main-menu button Trig When; then press the side-menu
button Within Limits.
H Press the side-menu button Upper Limit. Use the keyboard to set
the upper limit to 10 ns: press 10, then SHIFT, then n, and ENTER.
H Press the side-menu button Lower Limit. Use the keypad to set the
lower limit to 2 ns.
d. Change limits until triggering stops:
H Press SET LEVEL TO 50%.
H While doing the following subparts, monitor the display (it will stop
acquiring) and the front-panel light TRIG (it will extinguish) to
determine when triggering is lost.
H Use the general purpose knob to increase the Lower Limit readout
until triggering is lost.
H CHECK that the Lower Limit readout, after the oscilloscope loses
triggering, is within 2.5 ns to 7.5 ns, inclusive, for the TDS 684A or
is within 3.5 ns to 6.5 ns, inclusive, for the TDS 7XXA.
H Enter time on test record.
H Use the keypad to return the Lower Limit to 2 ns and reestablish
triggering.
H Press the side-menu button Upper Limit; then use the general
purpose knob to slowly decrease the Upper Limit readout until
triggering is lost.
H CHECK that the Upper Limit readout, after the oscilloscope loses
triggering, is within 2.5 ns to 7.5 ns, inclusive, for the TDS 684A or
is within 2.5 ns to 6.5 ns, inclusive, for the TDS 7XXA.
H Enter time on test record.