Peak Electronics DCA75 User Manual page 20

Atlas DCA Pro User Guide
Faulty or Very Low Gain Transistors
Faulty transistors that exhibit very low gain
may cause the DCA Pro to only identify one or
more diode junctions within the device. This is
because NPN transistors consist of a structure
of junctions that behave like a common anode
diode network. PNP transistors can appear to be
common cathode diode networks. The common
junction represents the base terminal. This is normal for situations where the
current gain is so low that it is immeasurable at the test currents used by the
DCA Pro.
Please note that the equivalent diode pattern may not be correctly
identified by the DCA Pro if your transistor is a darlington type or has
additional diode(s) in its package (such as a collector-emitter
protection diode). This is due to multiple pn junctions and current
paths that cannot be uniquely resolved.
In some circumstances, the unit may not be able to deduce anything sensible
from the device at all, in which case you may see one of these messages:
Unknown/faulty
component.
B
No component
detected.
Page 20
April 2015 – Rev 1.4
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