sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems preferred pairs for 551A

Gentlemen,
Is there a set of pairs that is preferred for outboard keys like the 551a on standard 565 and 2565 sets?

Thank you,
Shawn

565/2565 sets offer plenty of spare pairs. I prefer to use any lamp ground, typically white/green for line one as the common bus and then use the yellow/blue and yellow/orange pairs for signal buttons. Those pairs are fair game for this purpose. X64 sets by some manufacturers didn't have a yellow/blue pair, but any other yellow pairs can be used. Industry standard expected that the yellow pairs be used for misc. signaling. The only hard-fast expectation was that the yellow/slate was used for the ringer. While there was really no formal rule for signaling arrangements, technician courtesy assumed that you would maintain the same standard with all sets on the system.

On ITT, S/C and Northern Telecom sets, the yellow/orange pair was intended for buzzer use. Buzzers were field-installed.

On WE X64 sets, the same applied, but on their X65 sets, the yellow/green was wired to the factory-equipped 10 volt 7A buzzer. I never understood that since all of the other WE models used the yellow/orange pair for this purpose.

All X65 sets included violet/blue and violet/orange pairs that were also fair game. The remaining violet pairs were hands-off, since they were factory-wired for use with 4-type speakerphone sets. Mess with those pairs and your head will hurt.

Thank you that is very helpful.
I also thought the yellow green/yellow orange thing was unusual on WE sets of different models. Seems so unlike them to use different pairs based on the type of set I would have expected them to use the same pair on all sets. I am sure there was some reason but it does still seem odd.

Thanks again!

Some sets, as I recall, had Y/G wired to the Hold Lamp for a BLF (or other) function. I seem to remember using the Y/BN pair for signals.

I had trouble with some X64 sets where there was only one LG lead for the whole set (W/G). (There were only 16 pairs [actually maybe only 13! - I really can't remember anymore] inside the set's cable.) On long runs we experienced dim lamps on the set. We routinely commoned all the grounds at the power supply, but found it necessary to common the A1 Ground and the Lamp Ground Inside the set too, to fix the problem.

On those sets we converted Line Keys for signaling, and when they needed more lines we replaced the sets with X65 or Stromberg mini Call Directors (what was their number!)

And yea Ed, I never understood that Y/G buzzer thing with AT&T. Weird.


Sam