Performance Tests
4-42
TDS 420A, TDS 430A & TDS 460A Service Manual
H Press the main-menu button High-Low Setup; then press the
side-menu button Min-Max.
H Press the main-menu button Select Measurement for Ch1.
H Press the side-menu button -- m o r e -- until Amplitude appears in the
side menu (its icon is shown at the left). Press the side-menu
button Amplitude.
H Adjust the trigger MAIN LEVEL knob to obtain stable
triggered waveform.
H Press CLEAR MENU.
H Set the test signal amplitude for about three and a half divisions on
screen. Now fine adjust the generator output until the CH 1
Amplitude readout indicates the amplitude is 350 mV. (Readout
may fluctuate around 350 mV.)
H Disconnect the 50 Ω precision coaxial cable at CH 1 and reconnect
it to CH 1 through a 10X attenuator.
b. Check for Main trigger system for stable triggering at 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 of
2 ms/division and faster, TRIG’D remains constantly lit. It flashes
for slower settings.
H Press TRIGGER MENU; then press the main-menu button Slope.
H Press SET LEVEL TO 50%. CHECK that a stable trigger is
obtained for the test waveform on both the positive and negative
slopes. (Use the side menu to switch between trigger slopes; use the
trigger MAIN LEVEL knob to stabilize the trigger if required.)
H Leave the Main trigger system triggered on the positive slope of the
waveform before continuing to the next step.
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