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  TM 11-6625-539-14-3
tor device; therefore, any device failure would be
levels that the instrument can supply to the de-
caused by equipment operation and not by the
vice are controlled so that the accidental mis-
manner in which the test set is used.
placing of leads will not damage any semiconduc-
a. Transistors.
Type of failure
Ohms ( EB, C-B, C-E)
Beta
Open emitter-to-base junction . . . . . . . . . . .
Beta
reads infinity
.
.
Emitter-to-base ohms test. Meter indicates
infinity or emitter-to-base load.
Emitter-to-base ohms test. Meter indicates
Test set cannot be set for
Shorted emitter-to-base junction .-- . . . . .
BETA CAL.
O ohm.
High leakage between the emitter-to-base
Emitter-to-base ohms test. Meter indicates
Test set cannot be s-et for
BETA CAL.
junction.
low resistance.
Test set cannot be set for
Open collector-to-base junction
Collector-to-base ohms test. Meter indicates
BETA CAL.
infinity or collector-to-base load.
Test set cannot be set for
Shorted collector-to-base junction
Collector-to-base ohms test. Meter indicates
BETA CAL.
O ohm.
Collector-to-base ohms test. Meter indicates
Test set cannot be set for
High leakage between the collector to base
BETA CAL.
low resistance.
Collector-to-base ohms test. Meter indicates
Test set cannot be set for
Open
collector
to
emitter
BETA CAL.
infinity or the collector-to-emitter load.
Test set cannot be set for
Collector-to-emitter ohms test. Meter indi-
Shorted collector to emitter
BETA CAL.
cates O ohm.
Test set gives reverse indi-
Collector-to-emitter ohms test. Meter indi-
High leakage between the collector to
cation for BETA CAL.
emitter.
cates low resistance.
b. Diodes.
Meter indication
Type of failure
Ohm (GE)
In-circuit diode measurement
I
I
Shorted diode . . . . . . . . . . . . . . . . . . . . . . . . . O meter deflection . . . . . . . . . . . . . . . . . . . . . . 0.
O meter deflection . . . . . . . . . . . . Infinite or circuit resistance.
Open diode
failure, An open and a shorted diode both give
3-6. Determining Types of Failures
z e r o meter deflection on the in-circuit diode
measurement test. If the diode is shorted, switch-
The test set can be used to determine the type of
ing the meter to the CE OHMS test will give a
failure encountered, and some of the tests can
O-ohm reading. If the CE ohms tests shows a
be used to verify the findings of other tests. The
resistance or an infinity reading on the meter,
chart in paragraph 3-5 lists the types of failures
the diode is open.
that can be found and the manner in which the
test set can be used to determine the type of
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