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Performance Verification
1780R-Series Service Manual
4–39
d. Check that the 2T pulse amplitude is 1 IRE or less for NTSC (7 mV for
PAL) than the 2T bar amplitude.
e. Check that the 2T bar tilts 1 IRE or less for NTSC (7 mV for PAL).
f. Change the generator output signal to Field Square Wave. Select WFM
HORIZONTAL–ONE–FIELD mode on the 1780R-Series front panel.
g. Check that the Field Square Wave signal tilts 1 IRE or less for NTSC
(7 mV for PAL).
h. Select WFM HORIZONTAL–TWO–LINE mode.
i. Disconnect the Square Wave signal from the instrument.
30. Check Probe Input Gain
Requirement: Gain: Unity ±3%.
a. Connect the VAC output to the 1780R-Series front-panel PROBE input
connector. Do not terminate.
b. Select the following settings: RIGHT DISPLAY WFM+CAL, INPUT–
PROBE, CONFIGURE–On, PAGE 1, DC RESTORER–OFF, PAGE 2,
and PROBE–X1. (For NTSC: Select ABS UNITS–mV.) Select VAR on
the Waveform CRT menu; check that ABS is selected on this menu.
c. Set the VAC to 999.9 mV. Check that the +Lum button is pressed in and
the Lum/Sync button is out. Check that the correct television standard
(NTSC, PAL, or PAL M) is selected.
d. Use the VERT POS control to move the center two traces (bottom of the
upper signal and top of the lower signal) to the graticule baseline (0 IRE
for NTSC; 0.3 V for PAL).
e. Set the WAVEFORM GAIN to X5 and turn the Precision Measurement
control to adjust for a null.
f. Check that the CAL readout is between 970 mV and 1030 mV.
g. Check that the CONFIGURE button is On and PAGE 2 menu is
selected. Touch the PROBE X10 pad.
h. Set the VAC to 99.9 mV.
i. Repeat part d. of this step. Then, slightly readjust the Precision
Measurement control to obtain a null.
j. Check that the CAL readout is between 970 mV and 1030 mV.
k. Set the WAVEFORM GAIN X5 to Off. Leave VAR and ABS selected on
the Waveform CRT to perform the next step.