Tektronix 7B51 Instruction Manual page 58

Performance Check/Calibration-Type 71351
3. Check/Adjust Internal Trigger Centering (R135)
a. Reset the Type 71351 TRIGGERING MODE to
NORM, COUPLING to DC, SOURCE to INT and LEVEL/
SLOPE to 0/+.
b. Center the 50 kHz sinewave vertically on the CRT so
the display extends an equal distance above and below the
center horizontal line .
c. CHECK-The trigger point is at the center horizontal
line .
d. ADJUST-R135 to move the trigger point to the
center horizontal line .
e. CHECK-Change the Type 7A16 Position control and
check that the trigger point remains fixed at the center
horizontal line .
b. Set the low-frequency sine-wave generator to 50 kHz
and adjust the amplitude for a seven division display on the
CRT.
c. CHECK-Rotate the LEVEL/SLOPE control and
check that all levels of the display may be selected as the
sweep trigger point. Check for no trigger (no display) with
the LEVEL/SLOPE control near the top and near the
bottom .
5. Adjust External Trigger Input Compensation
(C145D, C140C)
a. Disconnect the sine-wave generator and change the
control settings as follows:
5-6
Type 7A16
Volts/div
.1 V
Type 71351
TIME/DIV
1 ms
TRIGGERING
COUPLING DC
MODE AUTO
SOURCE INT
b. Connect a 1 kHz square wave from the Type 106
Hi-Amplitude output through a GR to BNC female adapter,
a BNC coaxial cable, a 10X attenuator, a 50 ohm termina-
tion and a 20 pF normalizer to the Type 7A16 input.
Adjust the Type 106 amplitude for a five division display.
c. Reset the Type 71351 SOURCE to EXT. Connect the
1 kHz signal through the 10X attenuator, 50 ohm termina-
tion and 20 pF normalizer to the Type 71351 EXT TRIG
IN .
d. Connect a 1 X probe from the Type 7A16 input to TP
217 (Type 71351 trigger generator board) .
6 . Check Trigger Bandwidth
a. Change the control settings as follows :
Type 7A16,
Volts/Div .5 V
Type 71351
TRIGGERING
MODE P-P AUTO
COUPLING
AC
SOURCE
INT
TIME/DIV
10 ms
b. Connect a 30 Hz sine wave from the low-frequency
sine-wave generator through a "T" connector and coaxial
cables to the Type 7A16 input and the Type 71351 EXT
TRIG IN . Adjust the sine-wave amplitude for a 0.3 division
display. Reset the Type 71351 TRIGGERING MODE to
NORM .
4. Check Level/Slope
a. Change the
Range
control settings as follows :
Type 7A16
e. ADJUST-C145D (located on COUPLING switch
board) for best square corner on the square wave .
f. Remove the 10X attenuator and change the TRIG-
GERING SOURCE to EXT= 10 .
Volts/div 1 V
Type 71351
g. ADJUST-C140C (located on SOURCE switch board)
TRIGGERING
for best square corner on the square wave .
COUPLING AC
SOURCE EXT
h . Remove the square-wave input to the Type 71351 .