Interlinking Seriss 1A2 boards

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Greg Ercolano

Dec 12, 2021, 11:16:48 PM12/12/21

Ever since revision F1, the 1A2 seriss boards could be linked together with a ribbon cable so as to manage 4 CO lines and 8 separate extensions that can each be dialed on the intercom line by dialing "1" thru "8".

The general docs for interlinking cards can be seen in the "Expansion" chapter of the User Manual, which in the case of that REV-J5 manual, it starts on page 19. Or, this single page diagram showing the simple connection notes:

Some actual hook up notes: I suggest mounting both boards to plywood back board about 2" apart on rubber spacers, horizontally aligned, like this:


This way the ribbon cable can be run underneath the boards, so it's out of the way - folded "under" the boards with bends (but no "twists"):

Also, this way when all the phone extensions are connected, the fat cables can be "woven" cleanly off the board like this:

The new REV-J boards also have slots to allow one to utilize velcro straps (optional) to retain the connectors.

You can also provide additional strain relief at the bottom of the back board for the cables so they aren't just held in place by the connectors. This can simply be a sandwich of two pieces of hardwood with holes clamped together with the backboard using long bolts with wingnuts. This can to act as both a "wire comb" and strain relief, keeping the cables organized and prevent accidental tugs on the wire from straining the connectors:

To increase compression (if the holes are too large), just add a thin strip of e.g. felt or rubber, or other flexible material between the boards, then tighten down the wing nuts to grip the cables.
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