To eliminate a harmful influence on characteristics of an electronic device, and comply with abnormal tests in various standards although a constitution is simple and inexpensive when a power supply of the electronic device requires a high DC voltage.
In the abnormal test for short-circuiting a terminal T1 of a primary coil L1 and a terminal T5 of a secondary coil L2 in a transformer 10, a limiting resistor R1 for limiting a current flowing in a testing resistor R10 is provided between the secondary coil L2 and the terminal T5. When the terminals T1, T5 are short-circuited, an AC current generated in the secondary coil L2 flows to the ground through the terminal T1 and a capacitor C1, and does not flow in the testing resistor R10. The abnormal test is passed without increasing a resistance of the limiting resistor R1.
Katsumi Taguchi
Shinichi Mizuta
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