Tektronix 7623, Instruction Manual

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Calibration —7623/R7623 Service
49. Check-FAST Storage Writing Rate
a. Connect a 10 megahertz signal (20 megahertz option
12 ) to the input connector of the left vertical plug-in unit.
b. Press ERASE button.
c. Press the Single Sweep Reset button on the hori­
zontal time-base plug-in unit.
d. CHECK—That the signal is stored over a center
four vertical division by five horizontal division display.
50. Check/Adjust — FAST Stability
a. Press the ERASE button.
b. Press the Single Sweep Reset button on the hori­
zontal time-base plug-in unit.
c. CHECK —That the signal is stored and note quality of
display.
d. Press the ERASE button and wait one minute.
e. Press the Single Sweep Reset button on the hori­
zontal time-base plug-in unit.
f. CHECK —That the signal is stored; the quality should
be the same as in step c.
g. ADJUST-Increase the high speed prep voltage level if
step f fades up. Decrease high speed prep voltage level if
only part of the signal is stored in step f. If stability cannot
be achieved, raise the collector voltage and repeat steps a
through g.
c. Set the horizontal time-base unit for single sweep at a
sweep rate of 0.1 microsecond/division.
d. Connect the test oscilloscope 10X probe to the
Bi-Stable test point.
e. While erasing, set both the Variable Persistence Op
level and the Prep level (at zero voltage difference) to a
voltage level where the screen is just dark. Increase both
levels until the screen is fully saturated. Increase the Prep
level until the corners of the storage screen start to go dark
after an erase cycle.
f. Set the STORAGE LEVEL control counterclockwise.
g. CHECK—That the storage screen turns dark.
h. Connect the 50-kilohertz signal from the medium­
frequency generator to the input connector of the left
vertical plug-in unit.
i. Press the Single Sweep Reset button on the horizontal
plug-in unit.
j. CHECK—That the signal is stored across the screen.
Adjustment of the STORAGE LEVEL control may be
necessary to obtain a stored display.
k. CHECK-That the stored display is visible for 15
seconds.
52. Check/Adjust Variable Persistence Pulse
Amplitude
(See Fig. 2-10 for location of adjustments.)
a. Set the AUTO VIEWTIME/PERSISTENCE control
fully clockwise.
51. Check/Adjust Variable Persistence Mode
and Voltage Levels
a. Set the STORAGE LEVEL fully clockwise and press
the VAR PERSIST button.
b. Set the VIEWTIME/PERSISTENCE control in the
counterclockwise detent.
b. Connect test oscilloscope 10X probe to the Bi-Stable
test point. Set the test oscilloscope vertical deflection
factor to 1.0 volt/division (ten volts/division at probe tip),
and set the horizontal time-base unit for 0.5 millisecond.
c. CHECK/ADJUST - Check for a 22 volt variable per­
sistence pulse. Adjust-Variable Persistence pulse amplitude
(R1334) for 22 volts.
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