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Adjustment Procedures
1780R-Series Service Manual
5–57
e. Adjust Probe Calibrator Amplitude (A6R795) to obtain a null on the test
oscilloscope CRT display.
f. Disconnect the test oscilloscope from the VAC and the 1X probe from
the 1780R-Series CAL OUT connector.
g. Connect a Pulse & Bar signal from a television test signal generator,
through a 75 W feed-through terminator, to the 1780R-Series CH A
INPUT connector.
h. Select RIGHT DISPLAY WFM+CAL, INPUT-CH A, and WFM
HORIZONTAL-TWO-LINE mode of operation. Touch the VAR pad on
the Waveform CRT.
i. Rotate the Precision Measurement control to overlay the sync tip
(bottom) of the upper waveform on the white bar (top) of the lower
waveform.
j. Select FIX on the Waveform CRT menu to ensure that the amplitude set
in part i. of this step remains fixed when probe X1 and X10 gains are set
in Step 45.
k. Disconnect the Pulse & Bar signal from the CH A INPUT connector.
46. Adjust Probe Gain
a. Connect a Pulse & Bar signal from a television test signal generator,
through a 75 W feed-through terminator, to the 1780R-Series front-panel
PROBE input connector.
b. Select the following 1780R-Series front-panel and menu settings:
INPUT-PROBE and CONFIGURE-On. Select PAGE 2 and PROBE-X1
on the menu. Check that RIGHT DISPLAY-WFM+CAL and WFM
HORIZONTAL-TWO-LINE modes are selected on the front panel.
c. Adjust Probe Gain (A2R1107) so that the sync tip of the upper wave-
form and the white bar of the lower waveform are overlayed.
d. Attenuate the Pulse & Bar signal by inserting a 75 W 10X attenuator
between the coaxial cable from the signal generator and the 75 W
feed-through terminator used in part a. of this step.
e. Check that the CONFIGURE button is On. Select PROBE-X10 on
PAGE 2.
f. Adjust Probe X10 Gain (A6R295) so that the sync tip of the upper
waveform and white bar of the lower waveform are overlayed.
g. Select RIGHT DISPLAY-WFM. Leave INPUT-PROBE selected for the
next step.