| 摘要 |
PROBLEM TO BE SOLVED: To provide a low noise switching power supply device. SOLUTION: A square-cylindrical board assembly 90 with both its end parts opened is formed by connecting four boards 91-94 to each other and housed in the housing space SP of a casing 80. Noises are emitted by a transformer 24 and noise emitting electronic components such as a power transistor 221, a bridge diode 281, etc., which are arranged in the internal space SSP1 of the board assembly 90 and transmitted to the outside of an apparatus from the board assembly via an opening. However, heat radiating means 101 and 102 are placed near the opening, and the range through which the noises are transmitted is narrowed. As a result, the noise level transmitted to the outside of the apparatus can be reduced.
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