Tektronix 516 series, Инструкция по эксплуатации

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Calibration — Type 5 1 6
V
V.
Pig. 6 -4 . Location o f Power Supply lo tt po in t*
thus affects the deflection sensitivity. Do not adjust the high
voltage unless it is actually of tolerance or unless you
arc planning to perform a complete recalibration of the
instrument.
Measure the voltage at the —1675 ADJ. TEST PT. at the
top rear of the instrument. Set the HV ADJ. adjustment for
a reading of — 1675 volts. This voltage should not vary
more than 10 volts between the following limits: line voltage
set a* its lower limit (see Section 2) and the INTENSITY con­
trol set fully clockwise; line voltage set at its upper limit and
the INTENSITY control set fully counterclockwise.
5. Crt Alignment.
Check to see that the face of the ert
rests snugly against the graticule. If it docs not, loosen the
crt clamp and move the tube forward by pushing on the crt
tube socket. Then tighten the crt clamp.
Set the STABILITY control clockwise to free run the sweep.
Turn up the INTENSITY control until a trace is visible (it may
be necessary to adjust the VERTICAL POSITION control) and
adjust the FOCUS and ASTIGMATISM controls for the nar­
rowest trace width. W ith the VERTICAL POSITION control,
position the trace directly behind the center horizontal grati­
cule lino. If the trace is tipped relative to the graticule line,
rotate the crt alignment knob until the trace coincides with
the graticule line.
points indicated in Fig. 6-4. Set the —150 ADJ. control so
that the
150-volt supply is within 2% ond the other sup­
plies within 3% of their rated values. Do not adiust the — 150
ADJ. control unless one or more of the supplies is actually
out of tolorance or unless you are planning to porform a
completo recalibration of tho instrument. The calibration of
most of the circuits of the instrument w ill change if this con­
trol is adjusted.
2. Regulation.
To check tho operation of the regulator cir­
cuits, vary the output voltage from tho autotransformer be­
tween tho limits specified in Section 2 of this manual, at the
same time observing the required voltages. All of the volt­
ages should remain essentially constant and within specified
tolerances over this range of line voltage.
Amplitude Calibrator
3. CAL. ADJ. R879. When the CAL. ADJ. control is prop­
erly set, the calibrator output will be within 3% of the
voltages indicated on tho front panel. To make this adjust­
ment, connect a voltmeter between the CAL. TEST PT. jack
and ground, turn the AMPLITUDE CALIBRATOR control to
OFF, and adjust the CAL. ADJ. control for a meter reading
of exactly 100 volts. To assure suitable symmetry of the cali­
brator waveform, the voltage at this point should fall to be­
tween 45 and 55 volts when the calibrator is turned on (to
any of the output voltage settings). Readings outside of this
range ore generally caused by unbalanced multivibrator
tubes V875 or V885.
CRT Circuit
4. HV ADJ. R841. The adjustment that sets the high volt­
age determines the total accelerating voltage on the crt and
6. Graticule Alignm ent.
To check the alignment of the
graticule, obtain a free-running trace on the oscilloscope, as
explained in the provious step. Next move the trace, with
the VERTICAL POSITION control, to the top of the graticule
until the trace disappears. Then move the trace to the bot­
tom of the graticule until the trace disappears. If the grati­
cule lines are not centered in the usable viewing area, the
graticule is improperly aligned in the vertical plane. The
graticule may be repositioned by means of a nylon adjusting
cam, located in the lower left corner of the graticule.
To make this adjustment, remove the graticule cover and
loosen the set screw that holds tho positioning cam. By
insorting a pointed tool |such as a scriber or center punch)
Into the small holo, the cam may bo rotatod until tho groticule
lines are contered in tho usable viewing area. Then tighten
the set screw that holds the nylon cam, and reploce the
graticule cover.
7. Crt GEOMETRY ADJ. R 861.
The geometry of the crt
display is adjustable over a limited range by means of the
GEOMETRY ADJ. potontiomoter. To achieve optimum line­
arity, vertical lines are displayed on the crt and the GE­
OMETRY potentiometer is adjusted for minimum curvoture in
the lines. Nonlinearity is most noticeable at the edges of
the graticule.
Connect a time-mark generator to the A VERTICAL input
connector ond adjust the TIME/DIV. control and the A VERTI­
CAL VOLTS/DIV. control to obtain vertical lines as illustrated
in Fig. 6-5. Adjust the oscilloscope controls to obtain a sta­
ble display. Adjust the GEOMETRY ADJ. potentiometer for
straight vertical lines running parallel to the left and right
edges of the graticule.
The calibrator output waveform can be used in ploce of
the time-mark generator to moke this adjustment, but due to
the dimness of the trace, the adjustment is more difficult.
6-4