Tektronix 543B, Instruction Manual

Page: 29 / 90

Calibration — Type 543B/RM543B
Fig. 5-2. Location of internal adjustments and test points for time base, power supply, and amplitude calibrator.
To make this adjustment, connect the voltmeter between
the CAL TEST PT jack and ground (see Fig. 5-2), and adjust
CAL ADJ R879 for a reading of e100 volts. To
assure suitable symmetry of the calibrator waveform, the
reading at this point should not be less than 45 nor more
than 55 volts when the calibrator is turned on. Readings
outside this range are generally caused by unbalanced
multivibrator tubes (V875 or V885A).
3. High-Voltage Power Supply Adjustment
Connect the voltmeter between ground and the high-
voltage check point (sec Fig. 5-3), and set the HIGH VOLT­
AGE control (see Fig. 5-3) for a meter reading of exactly
— 1700 volts. Disconnect the voltmeter.
Check the regulation of the high-voltage power supply
by turning the INTENSITY control to 7 and defocusing the
trace with the FOCUS and ASTIGMATISM controls. Place
the HORIZONTAL DISPLAY switch to EXT and position the
defocused spot to the left side of the crt. Now observe the
spot while adjusting the line voltage 10% above and below
the design center voltage. The spot should not have shown
any "blooming".
4. Trace Alignment
Position the HORIZONTAL DISPLAY switch to NORMAL
(X 1 ) and adjust the INTENSITY, FOCUS, and ASTIGMA­
TISM controls to obtain a focused trace of normal intensity.
Position the trace behind the center horizontal grati­
cule line. If the trace and graticule line do not coincide
over the width of the graticule, adjust the TRACE ROTA­
TION control until they do.
5. Geometry
The geometry of the crt display is adjusted by means of
the GEOM control. To achieve optimum linearity, verti­
cal lines are displayed on the crt and the GEOM control
is adjusted for minimum curvature of the lines. Nonlinearity
is most noticeable at the edges of the graticule.
Connect 500 μsec markers from the Type 180A to the Ext
Input connector of the Type TU-7 and position the base line
of the markers below the bottom of the crt face so it is not
visible. Adjust the Type TU-7 Variable control so that the
markers over-scan the crt. Obtain a stable display with the
triggering controls, and adjust the GEOM control (see Fig.
5-3) for straight vertical lines running parallel to the left
and right edges of the graticule (see Fig. 5-4).
NOTE
The amplitude calibrator may be used for this
step, but due to the low intensity of the vertical
lines, the adjustment is somewhat more difficult.
6. Vertical Amplifier Low-Frequency Adjustments
Set the Test Function switch of the Type TU-7 to Common
Mode and adjust DC BAL R495 until the trace is super­
imposed on the center graticule line.
5-3