sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Station Block Layout

Hi guys,

I'm pretty new to 1A2. I salvaged an old KSU from work that I discovered in the sprinkler closet during our re-cabling project and thought it would be fun to make it work again. It still had power when I took it off the wall, but there have been at least two other phone systems since it was replaced (at least 15 years ago).

I took the KSU home and hooked it up to a few 564 and 2564 stations with help from bits of documents and drawings online. I'm using an Asterisk box to provide dialtone. I've also got a Melco KC-19 for intercom. At some point I'd like to add a 10 button station to the mix.

I found some documentation online and while it isn't for my particular KSU, it's pretty close. However, it was a pretty low resolution scan and the page with the station block layouts is pretty hard to read. So, to make things easier for me, I drew up what I believe to be a correct drawing of 6, 10 and 20 button station block layouts and I was hoping someone here would be willing to proof it. Drawing: Typical Station Block Layouts

Many thanks,

Tim

PS. I may send more of these your way, since all of the drawings I have now are pretty bad.

I'm not sure, but why does it skip pairs?

Tim -

Going from memory it looks right. I'll try to dig up the docs tomorrow and check. I do remember that Northern Electric/Telecom Logic 10 & 20 sets were different then WE/ITT/AE/Stromberg sets after the first 6 lines. (So watch out for those)

Jeff -

When you say "skip pairs" are you referring to the "A" leads jumping around and/or the Y/O, Y/Sl pairs?

On a six button set the first five lines went in order. Yellow/orange was the Intercom Buzzer, Yellow/ Green was the Hold Lamp and Yellow/ Slate was the Ringer. When they went to 10 button sets on 25 pair they tried to keep those signalling pairs standard.

Sam

Not sure either, but that's what the original looked like; there was definitely no text for the unlabeled pairs. The others were labeled, but blurry, so I made my own drawing. The empty pair for the 10 and 20 button blocks makes sense though, since there is only 1 A1 lead and 6A appears after 5A. However, the 3-1/2 blank pairs between 5L and SG on the 6 button block seems strange to me.

It's right. The pairs aren't skipped, they make logical sense so the TRa/Ax/Lg/L stays in order.
On a 10 button set, you fold a2/a9 a3/a8 a4/a7 and a5/a6 into the pairs and you always have T&R every 3rd pair. The only extremely weird punching is the L/L9 moves into the 23rd pair.

If you got extremely lazy and ran out of 3 pair jumper wire, you could install a 1a2 system with 2 pair jumpers after the 1st line. Of course, it was required and made for a neater looking frame if you actually did that, otherwise you ended up with a spare wire from every jumper hanging in the frame.

Carl

of 3 pair

Ok for example on the drawing
2T
2R
2A
blank
LG
L
Shouldn't the blank space be A1?

A1 leads were common, that's how you made the 10 and 20 button sets work. On the 6 button sets they were punched down as A, A1, but in the actual set they were spares.

It seems like the 10 and 20 button sets did away with the SG lead. What was its intended purpose?

Some of the 6 button sets I have used SG (BN-YL) and the OR-YL lead for the buzzer and the others used the OR-YL/YL-OR pair.

SG was Signal Ground. The ground part of the buzzer circuit (generally associated with an Intercom) Yellow/Orange, Orange/Yellow was the standard for buzzers, but I think Y/Br, Br/Y may have been a secondary buzzer.I'm pretty sure it was the buzzer pair for NT Logic sets.

The 6 button set had so many spares that they almost made up stuff to put on them.

They also had 12 button, 18 button and 30 button sets (Call Directors) that took 50 pr, 75pr and 125 pair feeds - though the 30 button call directors came out with 5 amphenols of 20 pair each - they left off the violets because there were so many spares.

When the 10 & 20 button sets came out, it was a big improvement and then the 30 button (2860 maybe?) came out and ran on "only" 75 pair!

Sam

Interesting stuff guys! See, I learn something every day here!