| 摘要 |
PROBLEM TO BE SOLVED: To easily execute the short-circuit test of a speaker line, and to surely detect a short-circuit. SOLUTION: In a self-fire alarm receiver A, voice outputting parts 2 and 4 to which plural speaker lines L1, and L2 are connected are provided with fuse corresponding to each speaker line L1 and L2. Then, when first signals are outputted from the voice outputting parts 2 and 4 to the speaker lines L1 and L2, and the lines L1 and L2 are in short-circuited state, the fuse corresponding to each line L1 and L2 is released, and when second signals are outputted to the lines L1 and L2, and the signals are not outputted from a speaker, it is judged that the speaker lines L1 and L2 are in circuit-short state by short-circuit detecting parts 3 and 5.
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