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Performance Verification
1780R-Series Service Manual
4–51
a. Check that the television test signal generator Color Bar signal is applied
to the 1780R-Series CH A INPUT connector. Check that the generator
Black Burst signal is applied to the EXT REF connector and this
connector is terminated into 75 W.
b. Check and/or set the 1780R-Series controls as follows: REF–EXT,
WFM HORIZONTAL–TWO–LINE, CONFIGURE button–On,
SYNC–AFC, COUPLING–DC, and DC RESTORER–OFF.
c. Check by switching between SYNC–AFC and SYNC–DIR on the
Vectorscope CRT menu that the Waveform CRT display remains locked.
d. Select SYNC–AFC and COUPLING–GND on the menu.
e. Check by switching COUPLING from GND to AC, that the display
freeruns then locks up within one second. (The display may lock up
immediately.)
f. Select SYNC–DIR and COUPLING–GND.
g. Check by switching COUPLING from GND to AC, that the display
locks up immediately.
h. Select COUPLING–DC. Check that SYNC–DIR is selected.
i. Use the HORIZ POS control to position the leading edge of the
horizontal sync pulse to graticule center.
j. Set the MAGNIFIER to 0.10 ms/DIV. Reposition the leading edge of
sync to graticule center.
k. Check that sync jitter is equal to or less than 12 ns (0.5 minor division).
l. Select SYNC–AFC.
m. Check that sync jitter is equal to or less than 30 ns (1.5 minor division).
n. Select SYNC–DIR and check that COUPLING–DC is selected. Press the
CONFIGURE button to exit the menu. Set the MAGNIFIER to OFF.
o. Disconnect the Color Bar signal from the instrument.
45. Slow Sweep Duration and Triggering
Requirement: Signal: APL change from 10% to 90%. Sensitivity: ≤0.4 V to
2.0 V peak-to-peak composite video with APL change. Front panel
selectable for either + or – (minus) triggering level change. Slow Sweep
Duration: 4 to 12 seconds.
a. Connect a 0% to 100% APL AC Bounce signal from the television test
signal generator, through a 75 W feed-through terminator, to the
1780R-Series CH A INPUT connector.