sundance-communications.com/forum Forums Other TDM Phone Systems 1A2 and Comkey Telephones & Systems 556a PBX

Note to mods: I apologize if this is the wrong forum for this post. This seems to be where all the "old timers" hang out.

Hello all - new to the board. I am a phone collector who'd like to do more than just display his phones, when possible. I just picked up this beast:

https://www.flickr.com/photos/7479548@N05/sets/72157600027248081/

and was hoping some folks here might have some insight into its operation and functions. It seems to me that all the components are there, but then again I don't know what all the components should be. The wiring is certainly gone, mostly snipped down to the solder. My goal, I guess, isn't necessary to get the whole thing "working," but to at least be able to power it, ring some phones with it, stage some connections with the cords, etc. Here are some of my thoughts/questions:

- Is this an independant PBX or a front panel for another, larger unit? I've read both.
- How many lines did it handle, 16 or 32?
- How is it powered? There are some posts marked "PWR" on the back, on the other side of the main power switch. I'm guessing 48v from batteries. Or was their CO power also (besides for the outside/trunk lines?)
- Just how old could it be? The front plate is marked 1949. The components, if I'm reading the WeCo date codes right, are marked from 1955 to 1967 to 1977 (!)
- Those big block connectors hanging off each line card - what the heck are they? I'm guessing they attach to a cable bundle that might serve a number of phones/pairs. I've never seen that connector before (there's a close-up amongst my pics.)
- How about documentation? There's a guy on ebay selling some docs (unknown whether they're complete) for $30, but surely someone must have them scanned somewhere...?

That's probably enough for tonight...hoping someone might get some enjoyment out of the pics as well. I've been reading the forums here for the last week, soaking up 1A2 knowledge and all the great Ma Bell stories!

-j

You are about going to need the schematic drawing for this and a power supply. Some of the smaller cord boards had the drawing inside a panel, so look around it may be in good enough shape to read if it's there. Once you have the drawing it will tell you the voltages you need, which you can probably get out of any 1A2 key system power supply.

I've seen a few online that had the schematics on the back panel, but mine is clean Good tip on the 1A2 supply, though, I do believe I have one or two lying around...

Actually, our non-bell cord board required -48 volts and had an additional rack of relays to operate the lamps and in-signals.

It could be that your relays are on the side of the cabinet, but I would guess that the lamps are still 48 volt.

Carl

I'm not sure of their function yet, but there are a heckuva lot of relays in this box. Lamps make sense.

Here's the link to some documentation on eBay:

https://cgi.ebay.com/Western-Electr...284QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

No idea if those are complete or not, or if they include wiring diagrams. And $30 seems a bit much for a guy to run off another copy of his .pdf of the docs. $1/page!

Not sure the manual is going to do you any good, you're not going to hook this up to a full blown switch anyway are you? All you have is the cord board for the PBX. What I'd try is just toning things out, shouldn't be too hard to hook up a tip and ring some control and lamp leads. I never worked on any cord boards off a PBX so I'm not sure about the switch, but that's the only way it would make sence to me.

Ahhh...I guess that pic on the ebay listing confirms it: "manual auxillary for 756a PBX." So that leads me to plan B, as you say - just hooking anything up to it to enable some rings, lights, etc.

Well that takes the burden off of me to get it completely "restored," then

Yep, it sucks. I checked my archives and all I have is how to fan the wires to a switchboard. Our docs came in two parts, the installation and the wiring drawings. Actually there were several wiring drawings :-)

The last one of these I saw was in an answering service installed about 1978 or so.

Carl

These old baby's had a manual ring key to signal the connected caller. The operator would patch the caller then throw the ringing key to ring the station.

This was most decidedly a Skokie IL prefix...

And also would only work on the 756 PBX... Unless you got a 4A console instead....

You would need a 555 for a stand alone board.