Learning Event 4:
DESCRIBE THE USES OF A SOLID STATE DEVICE TESTER
1.
There are several methods for testing solid state devices.
In this section
we will discuss the testing of diodes and transistors using a typical oscilloscope
and locally manufactured diode and transistor testers.
You must fully understand
the operation of the scope.
If you have any doubt about the operation of the
scope, review the section on scopes.
2.
Most diodes and transistors can be tested for shorts and opens with a
multimeter, when no solid-state tester is available.
The use of a multimeter is
discouraged because the meter's internal power supply can cause damage to the
component under testing or other components in the circuit under testing.
3.
Using a diode tester and an oscilloscope, you can easily test and compare
diodes.
Diode testers are commercially available.
In most cases your shop will
not be authorized to have any type of diode tester. You can build your own which
will be extremely accurate and efficient. Figure 3-13 shows the schematic diagram
of a simple diode tester, and Figure 3-14 shows the pictorial diagram. A variable
transformer provides the 0- to 110-volt input.
For testing most diodes a 6-VAC
input is sufficient, but you must exceed the breakdown voltage when testing a zener
With a variable 0- to 110-volt transformer, you can adjust the input to
test most zener diodes. The 6.3-VAC center tap (C/T) input to this tester (fig 3-
14) is for reference only.
This input must be variable to exceed the breakdown
voltage of a zener diode under test.
Figure 3-13.
Diode tester schematic
diagram
Figure 3-14. Locally manufactured
diode tester
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