Tektronix 7623, Инструкция по эксплуатации

Страница: 22 / 266

Calibration —7623/R7623 Service
d. Connect a 10X probe from the test-oscilloscope to
the Z-Axis test point (see Fig. 2-2) and the probe ground
lead to chassis ground.
e. Set the test-oscilloscope to DC input and a display of
5 volts/division (including probe attenuation), position the
trace to the center graticule line.
f. ADJUST-INTENSITY control for a display ampli­
tude 2 volts above the center graticule line.
g. ADJUST-CRT Grid Bias adjustment R1261 (see Fig.
2-2) until the trace on the 7623 (R7623) is just extin­
guished. Set INTENSITY for a viewable trace.
4B. Check Z-Axis DC Levels
a. Set the test-oscilloscope for 10 V/division, DC input.
Connect its 10X probe to the 7623 (R7623) Z-Axis test
point (see Fig. 2-2) and probe ground lead to chassis
ground.
b. Set the time base plug-in in the 7623 (R7623) to 50
ms/division not intensified and the test-oscilloscope time
base to 1 sec/div.
c. Set the calibration fixture Position control to posi­
tion the trace vertically off screen, and set the INTENSITY
control fully clockwise.
d. CHECK-The test-oscilloscope display amplitude
should be at least 58 volts, note this reading.
e. Set the 7623 (R7623) time base plug-in to 0.1
second/di vision.
f. CHECK-Pulse amplitude deflection on the test­
oscilloscope should decrease to between 25 volts to 35 volts
less than the amplitude in step d.
g. Disconnect the test oscilloscope 10X probe from the
7623 (R7623) and reduce the INTENSITY setting to a
normal intensity. Position the trace within the graticule
area.
5. Adjust Astigmatism
a. Set the 7B53A for auto, internal triggering at a sweep
rate of one millisecond/division.
b. Set the mainframe standardizer calibration fixture
Test switch to VERT or HORIZ AUX IN.
c. Connect the 4 V Calibrator pin-jack to the Aux In
connector of the calibration fixture with the BNC to
pin-jack cable.
d. Set the calibration fixture Position control for a
centered display, and the Amplitude control for about two
divisions of vertical deflection.
e. CHECK-CRT display is well defined.
f. ADJUST—FOCUS control and Astigmatism adjust­
ment R1045 (see Fig. 2-2) to obtain best display definition.
g. Disconnect the cable.
6. Adjust Trace Rotation
a. Set the INTENSITY control to midrange.
b. Move the trace to the center horizontal line with the
mainframe standardizer Position control.
c. CHECK-Trace aligns with the center horizontal line
within 0.1 division.
d. ADJUST—Trace Rotation adjustment R1181 (see
Fig. 2-2) to align the trace with the center horizontal line.
7. Adjust Y-Axis Alignment
a. Inter-change the 7B53A and mainframe standardizer
plug-in units.
b. Move the trace to the center vertical line with the
mainframe standardizer Position control.
c. CHECK-Trace aligns with the center vertical line
within 0.1 division.
d. ADJUST-Y-Axis adjustment R1190 (see Fig. 2-2) to
align the trace with the center vertical line.
8. Adjust Geometry
a. Remove the mainframe standardizer and install the
7B53A in the horizontal compartment. Replace the main­
frame standardizer in the left vertical compartment.
b. Set the VERT MODE switch to LEFT.
c. Connect the marker output of the time-mark gen­
erator to the Aux In connector of the calibration fixture
with an 18-inch 50-ohm BNC cable.
d. Connect the trigger output of the time-mark gen­
erator to the external trigger input connector of the 7B53A
with a 42-inch 50-ohm BNC cable.
e. Set the time-mark generator for one-millisecond
markers and one-millisecond triggers.
f. Set the calibration fixture Test switch to VERT or
HORIZ AUX IN and the Amplitude Step or Aux control
fully clockwise.
g. Set the 7B53A for auto triggering from the external
source at a sweep rate of 0.5 millisecond/division (magnifier
off).
2-10