Eico 950B - Technical Tests; Leakage Tests

range used, either balance will be obtained in the off-scale sector counter-
clockwise from the lowest value marked on the dial or the shadow angle will
widen to maximum only as the pointer knob approaches maximum counter-
clockwise rotation (except on the expanded ranges). If the unknown capacitor
is open or if the unknown resistor is shorted, the last-mentioned indication will be
obtained even when the RANGE switch is set at the lowest capacitance or
resistance range. '
if the unknown resistance or capacitance is larger than the maximum of the
range used, either balance will be obtained in the off-scale sector clockwise
from the largest value marked on the dial or the shadow angle will widen to
maximum only as the pointer knob approaches maximum clockwise rotation.
If the unknown capacitor is shorted or if the unknown resistor is open, the last-
mentioned indication will be obtained even when the RANGE switch is set at
the highest capacitance or resistance range.
NOTE: To obtain the correct value of extremely small capacitors, the value
of the distributed wiring capacity for your particular instrument should be sub-
tracted from the reading obtained. This compensation is required in practically
all instruments of this type. To measure the distributed wiring capacity, set
the RANGE switch at the lowest capacity range ("10mmfd - 5000 mmfd") and
‘adjust the pointer knob carefully for exact bridge balance with nothing con-
nected to the instrument terminals. You will have to observe the electron-ray
tube very closely to determine just where the maximum shadow angle occurs.
If the distributed wiring capacity readings is less than 10 mmf (off-scale) it can
be safely ignored and no compensation need be made.
Interpretation of the reading on the ratio scale when the instrument is used as
a comparator bridge depends upon the type of components being compared.
When inductances or resistances are being compared, divide the known value
of the standard by the reading on the ratio dial to obtain the value of the un-
known. -When capacitances are being compared, multiply the known value of
the standard by the reading on the ratio dial to obtain the value of the unknown.
lt is unnecessary to use the comparator range for measurement of resistances
and capacitances falling into the direct measurement range of the instrument.
However, for resistances and capacitors outside the direct measurement range
and for certain chokes, transformers, speakers, and coils, the comparator
method of measurement is very useful.
LEAKAGE TESTS
To test for leakage in paper, mica, or ceramic capacitors, set the RANGE
switch at the "PAPER-MICA TEST" position. To test for leakage in electrolytic
capacitors set the RANGE switch at the "ELECTROLYTIC TEST" position. In