Solar CE - Supplementary Information

The short
circuit test is effective even though the
condenser is shunted by en Inductance or resistance.
Make sure that the push buttons are pressed all the
way down
in
making the short
test. It sometimes hap-
pens that the meter reading will flicker as
the push
buttons are pressed down. This Is a
result of changing
the Internal circuit connections
and is not
Indicative
of an intermittent short. When the
button Is held
down and the meter needle flickers,
then this
is a posi-
tive Indication that
the condenser
is intermittently
shorted.
SUPPLEMENTARY
INFORMATION
Now a word
in general about
intermittent condensers,
supplementing
the information
previously given for in-
termittent opens
and intermittent shorts.
An intermittent
condenser may be the
result
of a
pressure contact
only, between the
terminals
and the
condenser
section proper, and this connection will be
broken if the unit
Is subjected to mechanical vibration
or
temperature changes. It is suggested that the
con-
denser be moved back and forth slightly
to show
up
such
pressure contacts.
In
case this
mechanical test does
not show
up
the
fault, the Quick-Check
leads
can be left connected
across
the capacitor
and
the receiver placed
in normal
opera-
tion until it has
reached
an operating temperature.
If the unit
becomes intermittent
as
a result of
tem-
perature,
the meter
indicator will
flicker.
The accuracy
of this check will
not be affected
even
if the condenser
under
test is shunted
by an inductance
or
a resistance.
The Quick-Check
offers
a convenient
method
for in-
dicating
electrolytic
capacitors which
have
high power
factor and
high
R.F. Impedance.
It
sometimes happens
that
in checking
an electrolytic
condenser there
will be
sufficient
capacitance
in the circuit
to indicate
that
the
unit
Is okay.
However,
the power
factor will
be so
high
as to
make the
capacitor
perform
unsatisfactorily
in the circuit.
The power
factor
check
is made by
connecting
the
Quick-Check
leads
across
the electrolytic
condenser
un-
der
test and
if the
condenser
is not
open, the meter
reading
will
decrease
from
5 ma.
to a lower reading.
If
the
pushbutton
"L”
is then depressed,
the
meter reading
will
indicate
whether
the
condenser
has
a high power
factor
or not. If the meter reading does not return to 5
milliamperes when the button is depressed, then
the con-
denser
is defective. It has either a high power factor
or high R.F. impedance
or
both.
If the
condenser is then shunted with
a
.1 mfd. tubular
paper condenser and as a result the
circuit disturbance
is
cleared up,
this
Is an
Indication of high R.F. Impe-
dance. If the circuit
disturbance is not cleared
up, and
particularly if high
hum is
noted, then the capacitor has
high power factor.
In either case, the capacitor should'
be replaced. A further check is
to
measure the capaci-
tance with the Wien
Bridge and if the value is substan-
tially below
the capacitance stamped
on
the
case, this
is a further indication
of an unsatisfactory unit.
In certain cases some electrolytic
condensers and fil-
ter type paper units show
up as opens {no change
in
meter
deflection when condenser
Is connected across)
when they are actually okay.
This is due to
the fact that
the inductance
of these condensers
Is particularly high.
Condensers with long leads will
have comparatively high
inductance values.
Also, certain condensers
due to their
construction have inherently high
Inductance values.
Therefore,
in order to properly check
these types of
condensers, it Is necessary
to make quantitative measure-
ments
as
well
as qualitative checks.
Condensers with high values
of inductance
are not
necessarily defective.
They may
or may not cause
in-
stability
depending
upon the circuit design
in which
they
are used. This will
have to be left
to the judgment
of the person
making the checks.
When
using the
Quick-Check section
of the instru-
ment, indications
are given
by the variation in the
meter
deflection and
not by the magnitude
of the
de-
flection.
When
working
on various
sets there will be
a difference
in the
magnitude of the
meter deflection
from one
set
to the
other when
one side
of the condenser
is con-
nected
to the
chassis. The magnitude
of the
deflection
plays
no part in the
testing of the
condenser as
Indica-
tion of
quality is given only
by the variation
in the meter
deflection.
The difference
in magnitude
of the
meter
deflection
from
set to set is due to the
variation
in im-
pedance from
chassis to ground.
If a case
occurs in which
no meter deflection
is given
when
the test leads are
connected
across a condenser
that Is grounded
to the chassis,
the analyzer
Is then
out of
adjustment.
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