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38
Checking and adjusting
V
The tolerances given below are factory tolerances, which apply only if
the apparatus is readjusted. They may deviate from the tolerances men-
tioned in the technical data (General part, chapter II).
A survey of the adjusting elements and their functions is given on page 37.
A. MAINS CURRENT
At 220 V, 50c/s the current taken from the mains must not exceed 420mA.
B. SUPPLY VOLTAGE +280 V
Check whether the supply voltage on the cathode of valve BI001 is
between 278 V and 282 V. -
If necessary, select another value for R101I.
C. RIPPLE ON THE SUPPLY VOLTAGE +280 V
Check whether the ripple voltage on the cathode of valve BI001 does not
exceed 10 mV. If necessary, select another value for RI004.
D. BARREL AND PINCUSHION DISTORTION
- Apply a sinusoidal voltage of 50 c/s to BUS.
- Also apply a sinusoidal voltage to BU5, however, of a frequency of
10 kc/s.
- Adjust the amplitudes of both voltages in such a way that a uniformly
lit square of 7.5 X 7.5 divisions is obtained.
- Reduce a possible barrel or pincushion distortion to minimum by means
of R309. When adjusted correctly, no point of the sides of the square
must fall within a concentric square of 7 x 7 divisions.
- Display a line on the screen which makes an angle of 30° with the Y
axis. (Two voltages of equal phase, frequency 1 kc/s, on BU3 and BU5).
- Check that this line is straight.
If necessary, adjust R309 in such a way that both requirements are met
as far as possible.
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