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Performance Verification
1780R-Series Service Manual
4–31
x. Check that the displayed amplitude is equal to or greater than 500 mV or
70 IRE for NTSC (490 mV for PAL).
y. Set the generator frequency to 2.68 MHz (3.53 MHz for PAL).
z. Check that the displayed amplitude is equal to or less than 500 mV or
70 IRE for NTSC (490 mV for PAL).
aa. Set the generator frequency to 4.18 MHz (5.03 MHz for PAL).
ab. Check that the displayed amplitude is equal to or greater than 500 mV or
70 IRE for NTSC (490 mV for PAL).
ac. Set the generator frequency to 4.48 MHz (5.33 MHz for PAL).
ad. Check that the displayed amplitude is equal to or less than 500 mV or
70 IRE for NTSC (490 mV for PAL).
ae. Select FILTER–FLAT mode.
af. Disconnect the sine wave signal from the instrument.
21. Check DC Restorer Operation
a. Connect a full field AC Bounce signal from the Television Test Signal
Generator Linearity module, through a 75 W feed-through terminator, to
the 1780R-Series CH A INPUT connector.
b. Set the 1780R-Series controls as follows: WFM HORIZONTAL–TWO–
LINE.
c. Press the CONFIGURE button to On. Check that COUPLING–DC and
DC RESTORER–OFF are selected on PAGE 1 of the Configure menu.
For NTSC: Select ABS UNITS–IRE on PAGE 2
d. Use the VERT POS control to position the signal blanking level to the
baseline (0 IRE for NTSC; 0.3 V for PAL) on the Waveform CRT
graticule.
e. Check that the signal blanking level does not bounce up and down.
Check that the white bar bounces up and down.
f. Select COUPLING–AC on the Configure menu.
g. Check that the signal blanking level bounces up and down.
h. Select DC RESTORER–SLOW on the menu.
i. Check that the signal blanking level moves less than 3 IRE for NTSC
(21 mV for PAL).
j. Select DC RESTORER–FAST on the menu.