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Performance Verification
1780R-Series Service Manual
4–41
32. Check Probe Tilt and Non-Linear Distortion
Requirement: Tilt: Less than 5% on a 50 Hz square wave (less than 4% when
using a 60 Hz square wave).
a. Apply a Field Square Wave from the Pulse & Bar module of the
television test signal generator, through a 75 W feed-through terminator,
to the 1780R-Series PROBE input connector.
b. Check and/or set the 1780R-Series controls as follows: RIGHT
DISPLAY–WFM, INPUT–PROBE, WFM HORIZONTAL–ONE–
FIELD, CONFIGURE–On, PAGE 1, COUPLING–DC, DC RESTOR-
ER–OFF, and PAGE 2, PROBE–X1.
c. Check that tilt is less than 5% on a 50 Hz flat field signal or less than 4%
on a 60 Hz flat field signal. (This is equivalent to less than 35 mV for a
50 Hz signal; less than 28 mV [4 IRE] for a 60 Hz signal.)
d. Set the CONFIGURE button to Off. Select INPUT–CH A.
e. Disconnect the signal and terminator from the PROBE input connector.
33. Check Timing Cursor Accuracy
Requirement: Accuracy: Within 5 ns, any delay within one line (64 ms).
a. Connect the television test signal generator Color Bar signal through a
75 W feed-through terminator to the 1780R-Series CH A INPUT
connector.
b. Press the TIME CURSORS button to On. Check that MEASURE and
SEPARATE (on the Vectorscope CRT Timing Cursors menu) are
selected. Check that WFM HORIZONTAL–ONE–LINE is selected on
the right front panel.
c. Use the 1780R-Series VERT POS and HORIZ POS controls to position
the leading edge of the white bar to the center of the graticule area.
d. Check that CURSOR 1 is selected. Turn the Precision Measurement
control knob counterclockwise until the DT readout stops changing.
e. Select CURSOR 2 and turn the Precision Measurement control knob
counterclockwise until DT readout stops changing.
f. Select CURSOR 1 and turn the Precision Measurement control knob
clockwise to place CURSOR 1 bright-up spot at the 50% point on the
leading edge of the white bar.
g. Select CURSOR 2 and turn the Precision Measurement knob clockwise
to obtain a DT readout of 63.555 ms on the Waveform CRT. (The readout
for PAL should be 64.000 ms.)