Author Topic: Powering up a 557A Cord Board  (Read 1355 times)

Offline simonwolfe

  • *
  • Posts: 13
Powering up a 557A Cord Board
« on: February 28, 2018, 05:30:50 PM »
Hello All,

Someone gave me an old 557A cord board.  it appears to be in pretty good shape and has tags on it dating it to around 1960-61.   The board came with a WECo 101G power supply which is from a 1A1 Key system. 

Unfortunately, I have very little knowledge on how to wire up a 557A.  I know that the vast majority of the board is secretarial lines that  should be connected to a CO and for the most part I can't do a whole lot with them. However, I believe I can tie my house line to one of the trunk lines and use it a a very large telephone set.  I also think that I can tie in two WeCo 500 telephone sets to the station lines and a) connect either of them to the trunk  b) connect them together and talk to myself. 

Thus far my "experimentation" has not yielded any great break throughs.  When the house line is tied to the first trunk line I get nothing.  When I tie in the power supply I get some relays to "click" and lights on the cords to light. I also can get dial tone on the trunk line but I have to wiggle the dial to do that, other than that I got nothing.   Also, I can't seem to pass the DT to either of the 500's or connect the 500's to each other.

So, the best I can tell I must be doing something wrong. I have a copy of the BSP for it but as far as I can tell it is a bit vague as to what power needs are and how to tie in the power.

Can you guys have any ideas?  Also, if you want I can go take some photos of it if that would help.

Thanks!

Offline RB

  • Hero Member
  • *****
  • Posts: 664
Re: Powering up a 557A Cord Board
« Reply #1 on: February 28, 2018, 05:41:25 PM »
Don't know about that board, but would suppose if you are getting lights, you must be close.
there should be a block of connection points on the back where power ties in.
maybe something wrong with the dial, I know it should interrupt the dial tone when dialing, but restore when at rest.
you may want to have the dial serviced. just my 2 cents.
good luck.
We would like to see pics too!

Offline simonwolfe

  • *
  • Posts: 13
Re: Powering up a 557A Cord Board
« Reply #2 on: February 28, 2018, 06:23:17 PM »
Hello,
Here are some photos.

Offline Jim Stettler

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 3705
Re: Powering up a 557A Cord Board
« Reply #3 on: February 28, 2018, 08:39:23 PM »
You can probably find some  information in the TCI Library.  They are a huge database  of telephone documents.
http://www.telephonecollectors.info/
 Nice toy,
Jim S.
You live, You learn,
You die, you forget it all.

Offline Babybearjs

  • Hero Member
  • *****
  • Posts: 2100
Re: Powering up a 557A Cord Board
« Reply #4 on: February 28, 2018, 10:10:50 PM »
a lot of work to get that going.... good luck with it....
John

Offline simonwolfe

  • *
  • Posts: 13
Re: Powering up a 557A Cord Board
« Reply #5 on: March 01, 2018, 07:39:55 AM »
You can probably find some  information in the TCI Library.  They are a huge database  of telephone documents.
http://www.telephonecollectors.info/
 Nice toy,
Jim S.

Thanks Jim,  I checked there and oddly enough came up with very little. I found that a bit surprising as their library is pretty darn good.  I do have the BSP for it but where to put the power was not well described, I'm assuming that was covered in training the Bell Systems guys got before going to work.

Offline RB

  • Hero Member
  • *****
  • Posts: 664
Re: Powering up a 557A Cord Board
« Reply #6 on: March 01, 2018, 08:47:19 AM »
Hi Simon
in your first pic, at bottom, there are 3 terminal blocks.
the second has BATT between 16 and 20? cant read, not clear enuf.
but that's where the batt connects.
that board is older than mine, but I believe, if you look at a 555 schematic, or other similar board,
you will find that the pin outs for those blocks, are quite similar too.
but that's where it all connects.
The other ones are for lines and trunks, I believe...among other things.
good luck and keep us posted on progress.
also, the light bulbs govern the supply voltage.
remove one CAREFULLY, and get the volt limit from it.
that will tell you the max voltage you can use for your power supply.

Offline simonwolfe

  • *
  • Posts: 13
Re: Powering up a 557A Cord Board
« Reply #7 on: March 01, 2018, 09:58:19 AM »
Hi Simon
in your first pic, at bottom, there are 3 terminal blocks.
the second has BATT between 16 and 20? cant read, not clear enuf.
but that's where the batt connects.
that board is older than mine, but I believe, if you look at a 555 schematic, or other similar board,
you will find that the pin outs for those blocks, are quite similar too.
but that's where it all connects.
The other ones are for lines and trunks, I believe...among other things.
good luck and keep us posted on progress.
also, the light bulbs govern the supply voltage.
remove one CAREFULLY, and get the volt limit from it.
that will tell you the max voltage you can use for your power supply.

Awesome! Thank you very much for the information. Yes, the bat is around 16 and 20 and that is where I'm tying in.  Great idea about the light bulb, lucky enough it came with a bunch of stuff from the old call service including a light bulb puller.  What I'm startign to think is that it sat so long in a storage container that the old capacitors have dried out.  Also, I don't know if the board was pulled from service because it started having "issues" and there was better things out there. Some of the stuff that came with it suggest it was use up to around 1991, a 30 year stretch isn't too shabby.

Offline RB

  • Hero Member
  • *****
  • Posts: 664
Re: Powering up a 557A Cord Board
« Reply #8 on: March 01, 2018, 11:27:32 AM »
don't worry about caps right now.
unless your board is very different than mine, the caps will be mostly film type, and even tho may be old, will still work for what you are wanting to do.
You will know if you need to change some when you get the phones talkin to each other.
Then it will be a matter of removing the cord set with a problem, and using the next one in line till you fix the bad one.
I can see a hunk of 25 pair in the bottom. it is prob how the board tied in with the incoming stations. maybe not...
You will need the batt to test anything on the board. as it provides power to the stations, as well as the relays in the cordsets/trunk moduals.
If you post a copy of your schematic, and a clear pic of the terminal blocks in the bottom, I can compare it to mine, and maybe mis lead you a little more? lol.

Offline simonwolfe

  • *
  • Posts: 13
Re: Powering up a 557A Cord Board
« Reply #9 on: March 01, 2018, 01:02:09 PM »
Actually, part of the issue is I don't have a schematic, I'm pretty much going after this blind.  There is a 100 pair that goes to the secretarial lines and a 50 pair that goes to the trunks, stations, and "anything left over".  I'll get a picture of that end of the punch blocks for you.  Thanks for your help!

Offline RB

  • Hero Member
  • *****
  • Posts: 664
Re: Powering up a 557A Cord Board
« Reply #10 on: March 01, 2018, 01:56:02 PM »
look here, Harry provided this:
https://drive.google.com/drive/folders/0B6eDAxemj1VHZjk2NTgwNWItMGUzNy00YzhhLWI4NGQtNzc3MTU4OGE5MjRh
555 stuff.
The 100 pair, is prob the lights, for the most part.
the 50 pair is gonna be of most use...guessing

Offline simonwolfe

  • *
  • Posts: 13
Re: Powering up a 557A Cord Board
« Reply #11 on: March 01, 2018, 04:40:33 PM »
Wow, that is a lot of good reference material.  Should be fun to go through it.

I took some photos of the back terminal block where the 50 pair goes. 


Offline RB

  • Hero Member
  • *****
  • Posts: 664
Re: Powering up a 557A Cord Board
« Reply #12 on: March 01, 2018, 05:15:13 PM »
ok, as far as i can tell,
GRD=ground
STAL=stations
TRK=trunk lines
You have BAT, and the MISC=extra stuff???
best guess here!

Offline simonwolfe

  • *
  • Posts: 13
Re: Powering up a 557A Cord Board
« Reply #13 on: March 01, 2018, 07:00:06 PM »
Yes, the Batt is quite interesting as there are multiple pairs going to various pins and several pins are jumpered together.  When I tie in you can hear some relays click and a few of the cords do sort of come to life but there is no power put out to the stations.   

Offline RB

  • Hero Member
  • *****
  • Posts: 664
Re: Powering up a 557A Cord Board
« Reply #14 on: March 02, 2018, 09:37:03 AM »
Yeah, there prob wont be...that's another part of the circuit.
They shud be tied in with jumpers somewhere.
You are gonna need the schematic to be able to trace one circuit all the way through.
You can try a couple things... put a meter on the tip and ring of one of the cord sets, and turn it on.
you shud find power on the cord.
For the stations, you will need a plug inserted into a socket to read voltage.
That's where the schematic comes in.