| 摘要 |
PURPOSE:To add a defect detecting circuit and a display lamp, which facilitate the defect detection, to every printed circuit board in the static device consisting of plural printed circuit boards. CONSTITUTION:When the input at a point (a) of a logical circuit board 20A is L, an output point a' is L if the circuit is normal, but it is H if the circuit is defective. Consequently, if the circuit is defective, the output of an EXOR circuit 22A becomes H, and the output of an OR circuit 23A becomes H, and a display lamp 24A is extinguished, and thus, the logical circuit board 20A is judged to be defective. When all of inputs (d)-(f) are L in a logical circuit board 21A, an output point d' is L also; but if the point d' is H because of the defect of an OR circuit or a TIMER circuit, the output of an EXOR circuit 22D becomes H, and a display lamp 24B is extinguished. Thus, a circuit which compares logical levels of input and output points is added to every logical circuit board and the state of the logical circuit board is indicated on the lamp to discriminate easily defective boards. |
