| 摘要 |
An instrument comprises an odd multiplexer ( 11 o) for sequentially selecting terminals connected to odd wires one by one, an even multiplexer ( 11 e) for sequentially selecting terminals connected to even wires on by one, odd relay switches ( 13 o<SUB>-1</SUB> , 13 o<SUB>-2</SUB>) for switching connection of the odd multiplexer ( 11 o) to a ground terminal, and even relay switches ( 11 e<SUB>-1</SUB>), 11 e<SUB>-2</SUB>) for switching connection of the even multiplexer ( 11 e) to a ground terminal. The multiplexers are operated at high speed in such a way that when one of the relay switches does not select connection to the ground terminal, and other selects connection to the ground terminal. By using such multiplexers, wires are sequentially selected at high speed, and the wire adjacent to the selected wire is grounded by the relay switch. While thus switching, the potential appearing at an input terminal ( 2 ) of a multiplexer is measured. In this way, an open test and a short test of wiring can be made at high speed.
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