Patent GB-1469128-A (GB)
Title: Modular main distribution frame
IPC: H02B1/20
Filed: 1974-06-11
Abstract: 1469128 Electric component assemblies WESTERN ELECTRIC CO Inc 11 June 1974 [14 June 1973] 25807/74 Heading H1R In a telephone MDP for multiple jumper connection of outside subscribers lines to internal exchange switching equipment (Fig. 4), plural main frame modules 405 are radially positioned around a stack 407 of inter connection circuit boards; a connection bay comprising equipment mounted on interfacing halves of circumferentially adjacent modules 405. Outside pairs enter over cables 408 two per module terminating as plural strips 401 and are uniformly distributed; the strips extending downwardly and radially outward of the frame structure. Internal equipment pairs are fed in over cables 409 two per module to terminate uniformly as plural strips 402 extending upwardly and radially outward of the structure. Direct interconnection between vertically adjacent outside and inside pairs is effected, e.g. by jumper 404a and between vertically non-adjacent pairs by jumpers 404b while for intermodular pair connections a first jumper, e.g. 404c interconnects terminals of strip 402 on a first module 405 to an interconnection circuit of stack 407, while a second jumper, e.g. 404c (not shown) interconnects a terminal of second module 405 to the same interconnection circuit at an electrically opposite point. The modules 405 are identical (Figs. 6, 7) and each comprises a bifurcated structure of mating mirror image members 620, 621 partially engaged along their left hand edges; each member having an outside and an inside cable channel 710, 711 providing conduits for dividing the outside cable 408 into subordinate cables 708a to 708d for distribution to terminal strips 401 and for grouping subordinate cables 709a to 709d from terminal strips 402 into a simple inside cable 409; the subordinate cables lying within the channels. These are conjoined for each member 620, 621 over upper and lower support members 712, 713, and the terminal strips 401, 402 have positive and negative strips relative to channels 710, 711. The latter are U-section in which the subcables lie and carry multiple insulated wire-wrap pins of the terminal strip (Figs. 8, 9 not shown), which have slotted apertured guide strips in either side co-operating with other slotted apertured guide strips of channels 710, 711 to maintain the jumpers in parallelism (Figs. 10, 11, 12 not shown), and to facilitate easy insertion thereof. The central stack of interconnection circuit boards 407 (Fig. 4) comprises (Figs. 13, 14) an alternating sequence of first and second types of board 1309, 1409 of which the first is a polygonal insulant substrate 1310 printed with plural adjacent parallel conductive bands 1313, 1314 and shaped to that a group of three adjacent edges 1315 to 1317, 1318 to 1320, 1321 to 1323 are provided for each module 405, the latter being perpendicular to the centre edge of each group. The parallel bands connect respective pairs to symmetrically opposed edges, e.g. 1318 to 1320 and 1317 to 1321 and printed circuit lands 1315 (Figs. 15, 16) terminate each conductor of the bands while blocks 1514 for terminals 1516 embedded or affixed are mounted on each respective edge, e.g. 1317, 1321 and soldered to the respective circuit lands. The second board 1409 is polygonal with band of parallel printed conductors 1413, 1414 connecting symmetrically opposed edges, e.g. 1417 to 1424 and 1418 to 1423 respectively located symmetrically about an axis of the intersections of edge pair 1420, 1421 and the diametrically opposed edge pair. Each conductor of 1413, 1414 connects similarly to those bands 1313, 1314 of board 1309, and for vertical alignment each block 1514 of boards 1309, 1409 has an extension projecting lip 1517 perpendicular to the plane of substrate 1310 which is overlapped by the block, so that the lip engages the adjacent board to prevent lateral displacement. Boards 1309 occupy even numbered positions and boards 1409 the odd numbered positions, and the odd and even numbered boards are respectively rotated 45 degrees clockwise relative to the next preceding odd or even numbered board to facilitate inter-bay jumper connections. The assembled stack 407 is attached to each module 405 through the pivot point of the bifurcated structure 620, 621. A systematic jumpering cycle and a terminal identification scheme are described in detail.