ITT 512 KSU Wiring

[njh621]

I recently purchased some 1A2 equipment, which included what I thought was an ITT 584A card rack in an apparatus mounting. Upon closer inspection, it looks like I actually got an ITT 512 KSU minus the power supply. See the following pictures:

http://imgur.com/a/JvuLW

There were several cutoff lengths of 25-pair that I de-wired from the 66-blocks, to make wire tracing a little easier. There's that terminal block mounted on the lower right-hand side, which looks like the power connection block. I'm thinking this unit has been heavily modified, as two pieces of 12AWG wire have been soldered to several of the terminals in that block. Those two wires exit with housing in a wrapped bundle with several smaller conductors (see pictures above.) Probing around with my Fluke, it looks like the 12AWG wires are connected to the 10VAC side.

I've been racking my brain trying to wire this thing, and the schematics in the manual weren't really helping. (For example, what's up with those 20 or so 'B' and 'R' terminations on the left-most 66 block?) I've got 13 400E KTU cards installed, and I know that there's 6 wires per 1A2 line. The power block is the real question, but I think I have an idea how to proceed with the 66 blocks. Any thoughts?

[poplar1]

You're right that there are 3 pairs or 6 wires for each line going to each phone. However, the 66 blocks inside the KSU have 5 pairs for each line--1st pair (T, R)  is the line input; next 3 pairs go to the telephone (T, R; A A1; LG L); 5th pair (B1 R1) is for the ringer or buzzer for that line.

So the first 3 pairs from the phone--White-blue, blue-white; white-orange, orange-white; white-green, green-white--will skip the first T R (where the line input is) and connect to the second T R, A A1, LG L, where the internal wiring on the other side of the block is W-O, O-W, W-G, G-W, W-Br, Br-W.

[njh621]

Based on that, it looks like I want to start line wiring with the 66 block second from the left. I'm guessing the left-most block is for the whole common audible signaling or some other signaling configuration? My plan is to use both 6 and 10 line sets. I was going to configure it so that if say Line 1 is ringing, then Line 1 on all phones rings simultaneously. Would I have to do anything special (i.e. go into a diode matrix) for that?

[poplar1]

You won't need a diode matrix if you have the same line(s) ringing on multiple sets. If your power supply has a ringing generator included, then you might want to use buzzers for the intercom, and ringers for the outside lines--or vice versa. The central office ringers or buzzers for Line 1 are connected to the B1/R1 leads associated with that line (9th and 10th pins on the 2nd block). If you have other lines ringing on the same sets or groups of sets, you can strap the R1 pins of the various lines at the block.

Since you are planning to use 6- and 10-button key telephone sets, you should punch down only the first A1 lead (orange-white) of each 25-pair cable going to the phones. Skip the other "A1" connections: all the other lines will have only 5 wires punched down.  These leads (slate-white, green-red, blue-black, brown-black) in the cable will be repurposed as "A" leads (not A1) for lines 6, 7, 8 and 9.

2nd block from left is for Lines 1-5. Left block appears to be for a dial intercom. Each of the B and R combinations (R2/B2, R3/B3, etc.) on the left block is for the intercom signal for one phone (buzzer or ringer).

[njh621]

Appreciate the detailed wiring instructions; you've solved half of my wiring headache! Now the fun part is figuring out the power wiring mess.

I spent a few more hours probing around with my Fluke, but didn't make much progress. There are either a lot of modifications going on, or I'm confusing the front side of the terminal block with the back. I'll post some detailed pictures shortly. Several of the smaller gauge wires from the bundle (shown in the previous picture) disappear into the bundle going to the edge connectors. They are slightly larger (possibly 20 or 22 AWG) than the 24AWG backplane wires, but they blend in very well. Since they don't appear to be for power, I'm wondering if they were used for paging KTUs at some point.