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
assembly. Set the Type 491 TIME/DIV selector
to 1 ms and
adjust the Triggering LEVEL control for a stable
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
1 6 . Check SAW OUT Signal Amplitude
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.
Sawtooth waveform and blanking waveform.