Position the zero timing mark and the start of the trace on
the left graticule line.
c. Check timing accuracy (3%) at each position of the
TIME/DIV selector. Marker input and Type 491 display for
15. Check VARIABLE Control Range
a. Equipment setup is given in step 14
b. Apply 5
ms markers to pin H of the Vertical Amplifier
circuit board
assembly. Set the Type 491 TIME/DIV selector
to 1 ms and
adjust the Triggering LEVEL control for a stable
display. One
5 ms marker/5 divisions.)
c. Turn the VARIABLE control fully counterclockwise.
d. Check-A minimum of five markers should be displayed
within the 10 division graticule width. Variable control range
2.5:1.
1 6 . Check SAW OUT Signal Amplitude
Location
of
trigger
and
sweep
adjustments.
a. Equipment setup is given in step 12.
c. Preset the Sweep Cal R787 to midrange. Adjust the
Sweep Gain R813 (see Fig. 6-15) for 10.5 divisions of sweep
the SAW OUT connector on the rear panel of the Type 491.
length. Adjust Sweep Cal R787 for 1 marker per division.
Sweep timing must be within 3% (1.2 minor divisions)
over the center 8 graticule divisions.
14. Check Sweep Timing Accuracy
a. Equipment setup is given in step 13.
b. With the Marker Output signal from the Time-Mark
Generator applied to pin H of the Vertical Amplifier circuit
board, adjust the LEVEL control for a stable triggered trace.
Fig. 6-16. Sawtooth waveform and blanking waveform.