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OM-2065 / Operation and Maintenance Manual
90SB51 / Spec. 7015-3 / Frequency Converter
Section 4. Transistor Module Test Procedure
1. Taking Resistance Measurements on the Transistor Module
a. Before taking resistance measurements, make certain that the transistor being checked is removed
(disconnected) from all other circuitry.
b.To take resistance measurements on the transistor module, use an ANALOG ohmmeter (NOT a
digital ohmmeter).
c. Set the ohmmeter to X1 on ohms.
d. For taking these measurements, place the ohmmeter leads as shown in Figure 2.
e. Approximate values of resistance for a good transistor are shown in Figure 3. When taking these
resistance measurements, take particular note of which company manufactures the transistor, as
values vary between manufacturers.
NOTE: A DIGITAL ohmmeter may be used to check transistors by using the X1 scale or DIODE CHECK
scale (if so equipped). However, measured resistance values may be quite different from those
shown in Figure 3. Defective transistors can be identified by resistance reading(s) that vary
significantly from readings on known good transistors.
Nov 1/90
Transistor Module
Figure 1
Chapter 3-4
Page 1
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