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Performance Tests
4–56
TDS 684A, TDS 744A, & TDS 784A Service Manual
H Press SET LEVEL TO 50%. CHECK that a stable trigger is
obtained for the test waveform on both the positive and negative
slopes. Press the main-menu button Slope; then use the side menu to
switch between trigger slopes. Use the TRIGGER LEVEL knob to
stabilize the trigger if required.
H Enter the pass/fail result on the test record.
H Leave the Main trigger system triggered on the positive slope of the
waveform before proceeding to the next check.
H Press the main-menu button Source; then press the side-menu button
–more– until CH 1 appears. Press CH 1.
4. Confirm that the Main and Delayed trigger systems are within sensitivity
limits (full bandwidth, for TDS 684A & TDS 784A = 1 GHz, for TDS 744A
= 500 MHz):
a. Hook up the test-signal source: Disconnect the hookup installed in
step 1. Connect, through its leveling head, the signal output of a
high-frequency leveled sine wave generator to CH 1.
b. Set the Main and Delayed Horizontal Scales:
H Set the horizontal SCALE to 500 ps for the M (Main) time base.
H Press HORIZONTAL MENU. Now press the main-menu button
Time base; then press the side-menu button Delayed Triggerable.
H Press the side-menu button Delayed Only.
H Set the horizontal SCALE to 500 ps for the D (Delayed) time base.
Press the side-menu button Main Only.
c. Display the test signal:
H Set the generator frequency to full bandwidth
(for TDS 684A & TDS 784A = 1 GHz, for 744A = 500 MHz).
H Set the test signal amplitude for about five divisions on screen. Now
fine adjust the generator output until the CH 1 Amplitude readout
indicates the amplitude is 500 mV. (Readout may fluctuate around
500 mV.)
H Disconnect the leveling head at CH 1 and reconnect it to CH 1
through a 5X attenuator.
d. Repeat step 2, substeps b and c only, since only the full bandwidth (for
TDS 684A & TDS 784A = 1 GHz, for 744A = 500 MHz) is to be
checked here.