Tektronix 7B92A Maintenance Manual page 70

b. Set the low-frequency sine-wave generator for
an eight-division display at 50 kHz. Center the display
vertically on the graticule.
c. Check-that all levels of the positive slope may
be selected for the sweep starting point as the MAIN
TRIGGERING LEVEL control is rotated throughout its
range, and that triggering occurs at least 3.5 divisions
above and below the center horizontal graticule line. See
Fig. 5-7 for reference.
d. Check-set the MAIN TRIGGERING SLOPE to
and repeat part c for the negative slope of the waveform.
e. Check-set the MAIN TRIGGERING SOURCE
to EXT and repeat part c of this step.
f. Check-set the MAIN TRIGGERING SLOPE to
+ and repeat part c for the positive slope of the
waveform.
A6. Preliminary Delayed Triggering Adjustment
a. Disconnect the 50-n cable from the MAIN
TRIG IN connector and reconnect it to the DLY'D TRIG
IN connector.
b. Set the 7B92A controls as follows:
MAIN TRIGGERING
SOURCE
MAIN TRIGGERING
LEVEL
Delayed Triggering
SLOPE
Delayed Triggering
COUPLING
Delayed Triggering
SOURCE
Delayed Triggering
LEVEL
DELAY TIME MULT
TIME/DIV OR DELAY
TIME
DLY'D Time/Division
c. Adjust Ext DC Bal, R230, Int DC Bal, R255,
and Trig Sens, R320, to midrange.
d. Set the vertical amplifier plug-in unit
volts/division switch to 50 mV.
@
INT
Near "0"
+
AC
INT
"0"
1.0
20 µs
10 ps/PULL FOR
ALT
5-20
Performance Check/Calibration-7B92A
e. Set the low-frequency sine-wave generator for
a four-division display at 50 kHz. Center the display
vertically on the graticule.
f. Adjust-Int DC Bal, R255, for a sweep trigger
point at graticule centerline (TRIG'D light on). See Fig.
5-5 for reference.
A7. Adjust Delayed Triggering Sensitivity
a. Adjust-Trig Sens, R320, for a sweeptrigger
point at approximately 0.3 division from bottom of
waveform as Delayed Triggering LEVEL control is
rotated through negative (-) portion of its range. See Fig.
5-6 for reference.
Setting trigger sensitivity so display is
triggered at less than 0. 1 division should be
avoided to prevent erratic triggering.
b. Reset the Delayed Triggering LEVEL control to
"0"
A8. Adjust Delayed Triggering External DC Balance
a. Set Delayed Triggering SOURCE to EXT.
b. Adjust-Ext DC Bal, R230, for a sweep trigger
point at graticule centerline (TRIG'D light on). See Fig.
5-5 for reference.
c. Set the Delayed Triggering SOURCE to INT.
A9. Check Delayed Triggering Level Range
a. Set the vertical
volts/divisior switch to 1 V.
b. Set the low-frequency sine-wave generator for
ar eight-division display at 50 kHz. Center the display
vertically on the graticule. (Lower the Delaying sweep
intensity with the oscilloscope intensity control.)
c. Check-that all levels of the positive slope of the
intensified zone may be selected for the sweep starting
point as the Delayed Triggering LEVEL control is rotated
throughout its range, and that triggering occurs at least
3.5 divisions above and below the center horizontal
graticule line. See Fig. 5-8 for reference.
NOTE
amplifier plug-in unit