Page 124 - Testing Electronic Components

The diagram in Figure 2 assumes you are testing an unknown type of
transistor. Set your meter to the lowest ohm’s range i.e. Rx1Ω. From the

six combination of test result you will know the transistor is belonging to
which type.

∞ ohm 0 Test Black probe Red probe Reading
No is connected is in ohms
to pin no connected
to pin no
1 1 2 Low

2 1 3 Low
3 2 1 High (∞)

- x1 Ω + 4 2 3 High (∞)
5 3 1 High (∞)
Black probe Red probe
6 3 2 High (∞)

1 2 3

Figure 2 : Identifying transistor type and pin leads

1. Connect the black probe of the multimeter to one of the transistor
leads, and connect the red probe to any of the other leads.

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