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Adjustment Procedures
5–56
1780R-Series Service Manual
j. Press the LINE SELECT button to turn it off. If necessary, readjust the
INTENSITY and FOCUS controls for best readout and trace definition.
k. Disconnect the Color Bar signal from the CH A INPUT.
44. Adjust Probe Compensation
a. Set the VAC amplitude to 199.9 mV. Connect the VAC output signal
through the 20 pF Input Normalizer to the 1780R-Series front-panel
PROBE input connector.
b. Check that the VAC +Lum button is pressed in, the Lum/Sync button is
out, and the correct television standard is selected.
c. Check that a Black Burst signal is applied to the 1780R-Series EXT REF
connector.
d. Press the button below the Waveform CRT.
e. Select 1780R-Series WFM HORIZONTAL-TWO-FIELD and INPUT-
PROBE mode of operation. Check that the CONFIGURE button is On.
Select PAGE 2 and PROBE-X10. Select PAGE 1 and check that DC
RESTORER-OFF is selected.
f. Use the VERT POS control to center the display on the Waveform CRT.
(The display will be unlocked or free running.)
g. Adjust Probe Comp (A6C493) for the squarest leading front corner. If
desired, set the WFM HORIZONTAL MAGNIFIER to X5 to check the
waveform.
h. Set the MAGNIFIER to OFF and press the CONFIGURE button to exit
the menu.
i. Disconnect the VAC and 20 pF Input Normalizer from the PROBE input
connector.
45. Adjust Probe Calibrator Gain
a. Check that no signal is applied to the CH A INPUT connector.
b. Connect a 1X probe from the test oscilloscope Differential Comparator
+Input to the 1780R-Series front-panel CAL OUT connector.
c. Connect the VAC output signal to the test oscilloscope Differential
Comparator -Input. Set the VAC output to 999.9. Check that the VAC
+Lum button is pressed in, the Lum/ Sync button is out, and the correct
television standard is selected.
d. Set the test oscilloscope controls as follows: Inputs DC coupled,
500 mV/Div vertical deflection factor, and 1 ms/Div sweep rate.