sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 600-Series Modular Panels?

Good evening,

I was reading through some BSPs that I found on the Web and I came across some references to 600-series modular panels. Just curious, what is a 600-series panel? They are mentioned in 518-010-101.

-Nelson

They are (were) all-plastic panels designed to provide 1A2 service. Unlike traditional KSUs that had a fixed number of card slots, modular panels could be stacked horizontally to create virtually unlimited configurations. These panels also incorporated built-in 66 block fields for each slot allowing easy access to inputs, outputs and option strapping. When set up properly, they aligned with modular backboard systems for a "Lego" type configuration.

The panels with red (actually pink) 66 fields (620) provided eight slots for 400 type line cards. The ones with yellow fields (641, 642, etc.) provided intercom and specialty circuits. These panels only supported two 8" cards or four 4" cards. Although gray plastic snap-on covers were available for these panels, they were rarely used.

All panels came factory-equipped with a power cable terminated with a Burndy connector. These plugged into modular power units (79 or 90 type). The 79 units allowed four panels to be connected, while the 90 units allowed for more. All power units included ring generators and interrupters in one unit.

These panels were tremendous labor savers since 25, 50 or 75 pair tails were not required, nor were their associated blocks. Cross connections were made directly from the panels' fields to the station or CO feeder blocks.

Other improvements were in-use lamps for each card slot, plus dedicated 70- type fuses that aided greatly in troubleshooting. In-use indication and blown fuses were great visual aids on a per-slot basis.

These panels came into widespread use in the mid 1970's and lasted through the end of 1A2 marketing by the Bell System operating companies.

Nicely done, Ed.

Yes, very well explained! That is kind of what I thought they were judging by the picture and how they are being used, but I was not sure.

Thanks Ed for the explanation. I love the wealth of information and intelligent people here at this forum!

I'd love to set up a 1A2 at home just for the experience. I bet I could find a complete system if I spent some quality time in my employer's basement. They save everything and always have! They had a 1A2 about 20 years ago before they upgraded to an Option 11.

-Nelson

Arthur, from a man of your stature and experience, I take that as the ultimate compliment. Thank you.