atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Station Block Layout

Your drawings are correct.
You might want to see if you can pick up on Ebay a copy of "Key Systems Service Manual", Vol I (tel sets) and Vol II (KSU's).

I installed and repaired approximately 3.7 zillion of these over the 30 years of my career. If you have a question, email me. One place I worked had 12,000 key sets, and 300 equipment closets. Every cable was a home-run, and we used no bridging clips.

Mount 66M-50 blocks and terminate the 25-pair running cables for each station, two to a block. Then you need to bring out all the features (that's what we call the TRAL&LG leads) on a 66B-25 block. It needs to be mounted on standoffs if you can't find the rare mounting brackets. I have used 3/4-inch long pieces of 1/2 inch thinwall conduit, or plastic tubing, with the mounting screws running through them, so that their front faces are even with the 66M-50 blocks of the station cables.

Mount some mushrooms for the 3-pair cross-connection wires to run around, and cross-connect the features to the appropriate buttons. The first X-conn to any station's first PU key uses all 6 wires. Subsequent X-conns use 5 wires. All 6 leads are punched down at the feature block, and at the station block, the O/W lead is carefully wrapped ("whipped")around the other 5 leads to keep them neat and tidy.

If this were a real installation, you would need to create enough feature blocks, using multiple wires, so that you do not need to use bridging clips at the 66M-50 blocks. That makes trouble-shooting easier. For your application, bridging clips can be used, but remember that any two phones that do not share all features still need individual X-conns.

For the dial ICM X-conns, the convention is T&R (Bl/W pair) Lg&L (Gr/W pair) and the O/W pair is used for the buzzer pair.

Aurthur, I contend that there is nothing prettier than the backboard of a well done 1A2 system with 2-3 13 cell racks, 50-60 10/20 button phones, lamp extenders, 2-3 intercoms spread across the phones with some phones having 2 or more I/C paths, and, of course, ring matrixs' all over the place. The only problem is you'd need a panoramic camera to take a picture of the 15 feet of backboard! And what fun watching the never-seen-1 youngsters. John C. (Not Garand)

John -

While my home setup isn't that spectacular, I do have on order red and blue backboards for the key system blocks and the station blocks. Also, some white backboards pre-populated with spools for routing the wiring. A diode matrix would make a nice addition, if anyone has one laying around

-Tim

Genuine matrix blocks are hard to find unless you can scavenge them from an old equipment closet in an office building. They take up a lot of space, so at AT&T we used to make our own, to save space on our backboards. Our home-made model fit right in with the rest of the 66-type blocks, and were easier to label and to maintain.

A diode matrix block can be made very simply and neatly from a 66B-25 or -50 block. Release the tabs on the back, and slide the back of the block off, and dump out and discard all the metal pins. Then take a 66M-50 and do the same, but carefully collect the pins from the M block.

Then put the two-position pins from the M block back into the B block, so that there is a space down the middle with no pins (what would be rows "C" and "D".) Take a bunch of diodes and terminate them in the empty space, one lead on row "B" and one lead on Row "E". The pins at row "F" can be looped...as many as needed...and sent to a station's CMB lead. The pins on row "A" come from the line card CMB leads. Don't forget to face all the diodes the same direction, (cathodes facing to the right) and to wire the ringers for "no capacitor".

The wiring convention we used for those 12,000 sets in one hospital was a single green lead from the 400D card to the matrix, and a single red lead from the matrix to the set's Slate/Yellow lead. The ground return (set's Yellow/Slate) was a single black wire to a 66 block that was nothing but ground.

Do you have any pictures of a setup like this?

Jeff:

You mean the matrix block, alone, or an entire installation?

Sorry, I have pictures of neither. I have no talent for photography, and my time machine will be going into the shop last Wednesday, if I can remember when I parked it.

I can make a matrix block as described above, and take a photo, if that's what you'd like to see. It might take me a few days.

I thought I remembered a picture of the matrix block here at one time...

yes, that was it. thanks!