atcomsystems.ca/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems Newbie Wiring Question - 1A2 CO T/R Lines - Stromberg KSU

Hello all,

First post here. I've come into possession of a Stromberg Carlson KSU, with about a dozen or more SAN/BAR 4200A cards in it. The KSU supports up to 25 lines; I just want to wire in my house landline to it for the moment. I also have two ITT 10 button phones. I've connected up one phone with the KSU, and when I push line button 1, the 1st KTU relay clicks, my line light turns on, and the LED on the KTU activates. So that part, I believe, is working well so far.

My question is - first of all, I don't have the manual for this KSU, and I feel like the SC manuals are harder to come by - perhaps I'm not looking in the right places. If anyone can point me in the direction of a manual for this larger KSU, I would be grateful.

Second, I would like to know where to punch in my landline T/R lines? I spent last evening with my multimeter tracking pins 9 and 14 back from the KTU to all the contacts on the punch-downs, and the only continuity I could find was with the phone T/R lines (the phone was not connected at this time). The labels on the 66 blocks didn't indicate any place obvious to me to connect up the CO lines.

I may be acquiring two more KSUs in the future; any suggestions on what to do with them? I really think one this size is enough for anything I'd ever want to do.

Any help would be appreciated,

Thanks,

Adam

Could you send some pictures of the phone? Or failing that a part number? Does the KSU have blocks mounted to the inside? If so, some pictures or a description of the labeling would be a big help.

Sam

Here's a picture of the unit overall:


Model number says S-C 684-A6R


Here are the internal blocks, the cabinet opens up for access:

So, as I say, I know where to punch down for the phone lines, but the CO lines are a mystery to me! Let me know if you'd like detail shots of each block, I took those shots as well, but didn't want to clog up the post.

Welcome to the wacky world of 1A2. You are correct in trying to trace 9 and 14 from one card slot. You need to unplug all the cards. Then send tone on 9 and 14 of one card slot and try to find the tone with a probe. You need to get these specialized telephone tools. A meter will make you crazy trying to do this particular tracing job. You can also try tracing physically the incoming CO pair from the card slot, to get a rough idea of where to find the other end.

The photos you sent are fine, as long as we scroll and make them bigger. I can see the designations that we recognize as the pairs going to the phones. (and some intercom wiring, too) Strangely, though, I don't see any common audible leads brought out on the 66 blocks. That's a discussion for another thread.

Here's a thought: there are a total of 25 slots. That means that the manufacturer needed to provide 25 incoming T&R. Is it at all possible that that there is a 25-pair amphenol plug somewhere on the back plane of the gate? Can you send a photo of the backplane? Can you try to see if such a connector exists?

If the CO T&R leads are brought out on any of the pins of the 66 blocks, they are not labelled obviously. We know where *NOT* to look (the various pins that are labelled with recognizable legends) so they MIGHT come out on the pins that have weird labels...but that's a long shot, and probably not realistic.

Take a look at the left-most block where you have your connections made for your station to 1T, 1R, 1A, A1, LG and 1L. Directly across from 1T and 1R on the right side of that same block are your tip/ring inputs for line 1. They are labeled T1 and R1. The next rows on the right, designated 0 and 19 are pins that would be used if a 20 pin KTU was installed in that slot (most cards use 18 pins, designated 1-18). Lastly, across from LG and 1L, you'll see 1B1 and 1R1, which are your ringing output (common audible, or CA) for that card slot. You'll want to connect the yellow/slate pair from your phones here.

This block, as well as the others, is split with separate connections on the left and right sides, similar to a 66M1-50 block. Be careful, though: The split isn't down the middle. For example, most are 5 left and 3 right where the line appearances are, but when you get closer to the bottom where the misc. connections are, they are 3 left, 2 center and 3 right. You have to look at the orientation of the clip's hook, or better yet, wiggle one clip and see how many others wiggle along.

For added information, note that at the top of the first and second blocks, you'll see access to the power supply and interrupter outputs. The third block is mostly vacant and reserved for a 19 station intercom, however some clip positions are factory-wired with the necessary ground connections.

Quite a nice and rare find for a KSU. The thing that I like about them the most is that they used standard 1/4" glass AGC fuses which are available anywhere instead of the flat 24- series ones, which are nearly impossible to find, even when they were available! It's in remarkably good shape and will give you years of service or fun.

Oh, I almost forgot. Welcome to the show, Adam. You've found the place for some of the best 1A2 support that you can get.

Ed is on the money. "1T, 1R" is Tip and Ring for Line 1 TO THE SET. Directly opposite it is "T1, R1" which is the Telco CO Tip and Ring for Line 1. The same applies for Lines 1 through 25.

Block 1 (on the far left) has lines 1 through 6. Block 2 has lines 7 through 12. Block 3 has Intercom T&R and Lamp leads on the top left and buzzer leads on the top right. The bottom of block 3 has Line 13. Block 4 has lines 14 through 19 and Block 5 has Lines 20 through 25.

it's an excellent unit, in that it offers the ability to use 20 pin cards in any slot. There aren't many 20 pin cards, but it's nice to have the ability there.

Sam

Some of the SC blocks were labeled TR for the CO Line and 1T 1R for the first trip of T R A A1 LG L.

Some of the older blocks had some interesting labeling. In any event, all of the equipment followed the same wiring convention as the Western Electric equipment.

Rcaman

Well, damn, Ed, you are the man! I must have been having selective perception there for a while. I didn't even see those designations. Well done!

I agree that the fact that it can accommodate 20-pin cards makes it a keeper.

Ed's right. But you have to copy and look at the image full size. Look down the right side of each block. All the CO T&Rs plus the CAs and some other stuff that I don't recognize.

-Hal

That got it! I wonder I didn't figure that out, but it really makes logical sense.

Now I have line one working, the light comes on when I press the line button and I receive my dial tone. When I call from my cell, the light for line one flashes, but I do not currently get any ringing (probably has to do with the lack of wiring for the common audible ringing?) Hold function also works (though I have no MOH source currently), but the light winks.

I looked closer at the card slots, and it looks like I can run 20, 40, and 80 pin cards (I read somewhere the 80 pin cards are supported by removing the inner card clips on the vertically adjacent slots). I hesitate to predict, but this is probably all the KSU I'll ever need.

Thanks so much for the insight on getting my CO lines hooked up!