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Adjustment Procedures
5–38
1780R-Series Service Manual
j. Select the FILTER-FLAT mode. Select COUPLING-DC on the
Configure menu. Press the CONFIGURE button to exit the menu.
32. Adjust Horizontal Timing
NOTE. Perform Step 39, Adjust Timing Cursors, before checking and adjusting
horizontal timing.
a. Check that no signal is applied to the CH A INPUT.
b. Check that the television test signal generator Black Burst signal is
connected to the 1780R-Series EXT REF connector. Check that this
loop-through connector is terminated into 75 W.
c. Check that the 1780R-Series controls are set as follows: RIGHT
DISPLAY-WFM, REF-EXT, WFM HORIZONTAL-TWO-LINE, and
MAGNIFIER-OFF. Check that the Waveform CRT readout indicates
10 ms/DIV.
d. Use the 1780R-Series VERT POS and HORIZ POS controls to position
the trace on the graticule baseline and so that it starts at the first major
graticule mark (located at the start or left end of the graticule baseline)
on the Waveform CRT. The baseline is the 0 IRE graticule line for
NTSC; 0.3 V for PAL.
e. Press the TIME CURSORS button to On. Select LOCATE and
SEPARATE on the Vectorscope CRT. Check that CURSOR 1 is selected
on the Waveform CRT.
f. Turn the Precision Measurement control knob counterclockwise until the
DT readout stops changing, Select CURSOR 2 and turn the control knob
counterclockwise until the DT readout stops changing, select CUR-
SOR 1.
g. Use the Precision Measurement control to place CURSOR 1 bright-up
area on the 2nd major graticule mark (first division mark). Select
CURSOR 2 and use the control to move the CURSOR 2 bright-up area
to the 12th major graticule mark. (The cursor dots should be 10 divisions
apart.)
h. Select MEASURE and CURSOR 1 on the Waveform CRT. Repeat part
g. of this step to place the CURSOR 1 and CURSOR 2 bright-up dots on
the 2nd and 12th major graticule marks, respectively.
i. Check that CURSOR 2 is selected. Slowly turn the Comparison Voltage
control until the DT readout is exactly 100.000 ms.
j. Press the 1780R-Series CALIBRATE menu button and touch HORIZ
CAL. Press the TIME CURSORS button to On.