Sweep Calibration; Check/Adjust Sweep Calibration (Swp Cal, A Front-Panel Adjust); Check/Adjust Magnified Sweep Gain (R785) - Tektronix 7B51 Instruction Manual

Performance Check/Calibration - Type 7851
g. CHECK-For proper triggering with the LE VEL/
SLOPE contro l at 0/+ and 0/-. Check for no trace with the
LEVEL/S LOPE control near the top and near the bottom.
h. Reset the Type 7851 TI ME/DIV to 50 }Js and
MAGNIFIER to XL Set the Type 191 to 50 kHz and
adjust the amplitude for a four division display. Adjust the
Type 7851 LEVEL/SLOPE for a stable display. Reset the
TRI GG ERING MODE to SINGLE SWEEP.
1.
CHECK- Remove the signal from the Type 7A16.
Press the Type 7851 RESET bu tton and check that the
READY lamp is lighted. Wh ile observing the display, recon-
nect the signal to the Type 7A16 and check for one
displayed sweep (it may
be
necessary to increase the
INTENSITY to observe the display). Check that the
READY lamp is out at the end of the sweep.
j. Reset the Type 7851 TRI GGER ING MODE to p.p
AUTO and SOURCE to EXT. Adiust the Type 191 for a
1.5 division (750 mV) display.
k. CHECK- Rotate the LEVEL/SLOPE throughout its
range and check for stable t riggering at all positions.
I.
Change the " T" connector from the Type 19 1 to the
low-frequency sine-wave generator output connector.
m. Set the Type 7851 TRIGGERING COUPLING to
DC and SOURCE to INT. Set the Time/ Div to 10 ms.
n. Set the low-frequency sine-wave generator to 50 Hz
and adjust the amp litude for a 2 d ivision display.
o. CHECK-A stable display can be obtained.
p. Remove the 50 Hz signal from the Type 7A16 and
Type 7851.
9. Check /Adjust Sweep Calibration (SWP CAL. a
front-panel adjustment)
a. Reset the Type 7851 TI ME/ DI V to 1 ms and
COUPLING to AC.
b. Apply 1 ms markers from the Type 184 time-mark
generator to the Type 7A16 Input.
5-8
Fig.5-2. Typica l CRT displ ay showing correct $WHp ca libration.
c. CHECK- CRT display for one 1 ms marker for each
division between the second and tenth vertical lines (see
Fig. 5·2).
NOTE
Unless otherwise noted, use the center eight hori-
zontal divisions when checking or adjusting timing.
d. ADJU ST - SWP CAL, a front·panel adjustment, for
one marker for each division . The second and tenth markers
must line up exactly with their respective graticule lines
(use the horizontal POSITION control as necessary to li ne
up the display).
e. CHECK- Timing accuracy is within 5% over any two
division interval with in the center· eight divisions.
f. INTERACT ION: Check 10, 11, 13, 14, 15, 16 and
17 .
10. Check/ Adjust Magnified Sweep Gain (R785)
a. Set the time-mark generator for .1 ms markers.
b. Set the Type 7851 MAGNIFIERtoX10.
c. CHECK- CRT display for o ne .1 ms marker for each
division between the second and tenth venicallines.
d. ADJUST - R785, Magnifier Gain, for one marker for
each division (use the horizontal POSITION cont rol as
necessary to line up the display) .