Boxoffice-April.07.1958

SOUND TROUBLE EASILY CORREaED
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Leads may became crossed or electrolytic
and dielectric film may become damaeed
and cause shorts: excessive voltage will
cause breakdown: exposure to excessive
heat when placed near a ballast tube, defects
in manufacture and wrong jwlarity
connection. Most of the common failures
of electrolytic capacitors are crossed leads,
op)en circuit due to broken leads, leakage
and short circuit in the dielectric, etc.
CAN DEVELOP SHORTS
Do not confuse the electrolytic with tubular-type
coupling and by-pass condensers.
However, these condensers develop shorts
and "opens" due to breakdown In the dielectric.
For fixed condensers, there are various
sizes, namely. .001. .002. .005, 10 m^d.
400-volt capacity, etc. Various makes of
amplifiers will use "special" sizes of condensers,
therefore it would require too much
space to list all of them. We have listed a
few of the most popular ones.
Your schematic
or parts catalog will give you a complete
listing of all the condensers for any
replacements.
Resistor replacement Is necessary when
It becomes defective. It should be an exact
duplicate, or as near as possible, and
the wattage rating Is important. If the resistor
is too low in rating, it will overheat,
which will cause It to open or change its
value. The correct value is given in the wiring
diagram and should be adhered to. The
best procedure is to follow the manufacturere'
recommendation. If the schematic
gives a certain resistance, let's say 75,000
ohms, a slight variation of 5 or 10 per cent
will not hurt. However. If the diagram or
the color codinn of the resistors indicates
that a resistor having a 5 or 10 per cent
tolerance is recommended, it is usually wi.se
to stay within this tolerance. The amplifier
will operate more efficiently by makinR
component replacement according to the
manufacturer's recommendation, and will
deliver better quality sound reproduction.
It is a good idea to obtain a color code
chart for resistors from your local radio
supply house. You will find this chart very
helpful in identifying resistors in your amplifier.
By having a color code chart
handy, you will not have to memorize the
values of various colors used.
There is an increasing use of ceramic capacitors.
They have very good stability and
give good service. These new ceramics will
be found in many modern amplifiers: they
are subject, of course, to short circuit and
open circuit. Short circuits are the most
common trouble. Mica condensers are in
general subject to the same troubles as
ceramic and paper condensers. Proper connections
and the "correct" value will contribute
to less trouble with any type of capacitor
or
resistor.
TYPES OF RESISTORS
There are several types of resistors used
in older model and newer models of amplifiers.
There is a metallized, plastic covered,
a very popular type