Tektronix WFM700 Series, Руководство по обслуживанию

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Adjustments
3- 4
WFM700 Series Waveform Monitors Service Manual
This adjustment calibrates the Serial Out amplitude from the Video Module.
Video Module Types.
WFM700A, WFM700M, and WFM700HD
Requirements.
HDVG, 1080-line color bar signal; test oscilloscope; 75
8
coaxial
cable
1. Connect the HD video generator to the Video Module under test using a 75
8
cable.
2.
Set the HD video generator for a 1080i 59.94 100% color bar signal.
3. Select the appropriate WFM700 Video Module (1 or 2) and input (A or B).
4.
Press the
WFM
button.
5. Connect the SERIAL OUT to the 75
8
input of the test oscilloscope using a
75
8
cable. Use a 75
8
-to-50
8
adapter on the input of the test oscilloscope
if necessary.
6. Adjust R296 for a display of 800 mV ( 10 mV) on the test oscilloscope.
The following substeps will help obtain a measurable display on the test
oscilloscope.
a.
Ensure that the termination is correct on the test oscilloscope.
b. Set the vertical scale to 200 mV/div, horizontal scale to 5 ns/div, and the
trigger position to 90%.
c. Set the display style to dots.
d.
Set the trigger level to zero, and to neglect glitches of either polarity for
widths to 30 ns.
e. The oscilloscope display should show a few random transitions followed
by 30 ns with no transitions. This is followed by the triggering transi-
tion. See Figure 3--2.
f. When measuring, disregard signal noise. Measure the waveform
amplitude from the centers of the high and low levels in the region from
5 ns to 10 ns before the triggering transition.
Serial Out Amplitude
Adjustment