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Adjustment Procedures
5–28
1780R-Series Service Manual
e. Adjust Var Gain Centering (A2R514) for a Calibrator signal amplitude
of 65 IRE for NTSC (or 450 mV for either NTSC or PAL).
f. Press the CONFIGURE button and select COUPLING-DC.
g. For NTSC only: Check that ABS UNITS-mV is selected on PAGE 2.
h. Set the VAR WAVEFORM GAIN to Off.
i. Press the CALIBRATE button. Select CAL SIGNAL-ON and VERT
CAL.
j. Check that REF-EXT and WFM HORIZONTAL-ONE-LINE are
selected on the right front panel.
k. Adjust the 1780R-Series Precision Measurement knob until the traces
are exactly 1 V apart as displayed on the Waveform CRT. Use the VERT
POS control to align the traces with the graticule lines.
l. Select 1780R-Series FILTER-LPASS.
m. Adjust Low Pass Filter Gain (A2R754) so the traces are exactly 1 V
apart to match the amplitude obtained in part k. of this step.
n. Select 1780R-Series FILTER-FLAT.
o. Press the CALIBRATE button to exit the menu and the CALIBRATE
mode.
p. Set the VAC for 199.9 mV output.
q. Set the front panel RIGHT DISPLAY to WFM and WAVEFORM
GAIN-X5 to On. Use the VERT POS control to position the traces into
view.
r. Adjust X5 Gain (A2R422) for 1 V amplitude indication as displayed by
the traces on the Waveform CRT. (Signal amplitude is 199.9 mV.)
s. Set the WAVEFORM GAIN-X5 to Off.
t. Disconnect the VAC from the CH A INPUT.
20. Adjust Voltage Cursors
a. Check that no signal is applied to the CH A INPUT.
b. Select RIGHT DISPLAY-WFM+CAL. Press the CONFIGURE button to
On. Select COUPLING-GND. (For NTSC: Check that ABS UNITS-mV
is selected on PAGE 2.) Press the CONFIGURE button to Off.
c. Check that the CAL readout is 1000 mV on the Waveform CRT.
d. Press the VOLTAGE CURSORS button to On.