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If the horizontal drive control is misadjusted,
the right side wedge in the picture appears to be shorter
than the left one, and the outer circle is not round. If
the horizontal linearity control is misadjusted, the picture
appears to be cramped in the middle. If the width control
is misadjusted, the right wedge of the picture is somewhat
longer than the left one, and the center circles of the
test pattern are ovals instead of circles.
After making these adjustments, it may be necessary that
you readjust the focus control, and "touch up"
the adjustment of the ton trap. Some of the modern receivers
have an age control mounted on the rear of the chassis.
To adjust this control, tune in the strongest station that
can be received, and set the contrast control to maximum.
Then adjust the age control to where overloading in the
form of a severely distorted picture just begins to appear.
Then, turning the contrast control down should give normal
contrast, and if the age system is operating properly, there
will be no overloading on any signal.
External
Interference
Set the receiver to a channel that exhibits interference,
and then disconnect the antenna lead from the set. If the
interference disappears, it is being picked up by the antenna
or the lead-in. If removing the antenna from the receiver
did not clear up the interference, the interfering signal
is entering the receiver by way of the power lines.
Most
interfering signals that enter the antenna terminals of
a TV receiver can be removed by use of a high-pass filter.
This filter rejects all signals lower than the frequency
of channel 2. If you encounter a number of interference
problems, it might be well to purchase a commercial high-pass
filter and carry it in your service kit.
Frequently, interfering signals that travel into the set
by way of the power line can be reduced by use of a commercial
power line filter. These units are available from the large
wholesalers throughout the country.
Specific interference problems that do not respond to these
corrective measures will require further experimentation.
Fig.
9. This type of pattern will be produced
if the horizontal drive control is misadjusted.
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