Main distributing frame board for an electronic switching system

Claim 1

A main distributing frame board mounted on a pair of vertical frame members of a main distributing frame of a switching office and interconnecting an inside cable connected to a switching equipment of said switching office and an outside cable connected to a subscriber station, said frame board comprising: a plug-in type connector connected to said inside cable; a first terminal block having U-groove clip terminals connected to said connector; a second terminal block having U-groove clip terminals connected via jumper wires to said clip terminals of said first terminal block, each of said first and second terminal blocks having U-groove portions of said clip terminals projecting toward a front housing wall, said clip terminals being arrayed in two zigzag rows, and lead portions projecting towards a housing rear portion, strain relief members provided close to said U-groove portions, and wire guide means provided on a housing side wall; a third terminal block having U-groove clip terminals connected to said outside cable; a receptacle integral with said third terminal block and having female contact terminals connected to said clip terminals of said second and third terminal blocks and a female contact terminal for making a ground connection and for receiving male contact terminals of a protector module having a protection device, said receptacle with said female contact terminals coming into contact with said male contact terminals of said protector module, said terminals being disposed in a row in a slot exposed to said front wall, said slot being arranged at a higher stepped portion of said front wall to dispose said female contact termainals therein, and U-groove clip terminals and strain relief members for wires which are press-connected into said clip terminals, said clip terminals and strain relief members being disposed at a lower stepped portion following said higher stepped portion, said receptacle having a wire guide on a side wall adjacent to said front wall; at least one back wiring board having said connector, said first, second and third terminal blocks, and said receptacle mounted thereon; a shelf with said back wiring board fixed thereon and integrally mounting said connector, said first, second and third terminal blocks and said vertical frame member of said main distributing frame, said shelf having a pair of brackets and being fixed on said brackets to a pair of vertical frame members of said main distributing frame, said connector and said clip terminals of said first terminal block being oonnected through a printed conductive pattern formed on said back wiring board, said receptacle and said clip terminals of said third terminal block being connected through a printed conductive pattern formed on said back wiring board, and a ground connection terminal of said receptacle being grounded through a printed conductive pattern formed on said back wiring board.