Classic Rotary Phones Forum

Telephone Switching => Magneto & Manual (Cord Boards etc) => Topic started by: simonwolfe on February 28, 2018, 05:30:50 PM

Title: Powering up a 557A Cord Board
Post by: simonwolfe 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!
Title: Re: Powering up a 557A Cord Board
Post by: RB 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!
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on February 28, 2018, 06:23:17 PM
Hello,
Here are some photos.
Title: Re: Powering up a 557A Cord Board
Post by: Jim Stettler 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.
Title: Re: Powering up a 557A Cord Board
Post by: Babybearjs on February 28, 2018, 10:10:50 PM
a lot of work to get that going.... good luck with it....
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on March 01, 2018, 07:39:55 AM
Quote from: Jim S. 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.

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.
Title: Re: Powering up a 557A Cord Board
Post by: RB 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.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on March 01, 2018, 09:58:19 AM
Quote from: RB 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.

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.
Title: Re: Powering up a 557A Cord Board
Post by: RB 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.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe 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!
Title: Re: Powering up a 557A Cord Board
Post by: RB 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
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe 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. 

Title: Re: Powering up a 557A Cord Board
Post by: RB 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!
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe 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.   
Title: Re: Powering up a 557A Cord Board
Post by: RB 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.
Title: Re: Powering up a 557A Cord Board
Post by: HarrySmith on March 02, 2018, 10:56:11 AM
I have attached a circuit diagram from my stash of 555 documents.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on March 03, 2018, 08:27:25 AM
Quote from: HarrySmith on March 02, 2018, 10:56:11 AM
I have attached a circuit diagram from my stash of 555 documents.

Cool, Thank you!
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on March 03, 2018, 08:37:07 AM
OK, So this is where I'm at.  I took a very careful look with my meter in hand and found that on the 50 pair in the blue binder, the firs group they too all the tips and put them to ground and all the rings and pit them to various points on the Batt pins. I tied all the tips together and the rings together and I'm pretty sure that is power.  I then use RB's idea of looking at the bulbs. The board uses the M1 bulbs which according to BSP 032-501-801 is rated at 48v. The 101G power supply I'm using is only good for about 26vdc. I also noticed that when I had the house line tied into the first trunk line I actually got things to light up a bit. As you all know the house line is running at 48v.  So, it appears I need to find a 48vdc power supply somewhere. 

I'll fiddle with it some more and report back.

Thank you all for your help!
Title: Re: Powering up a 557A Cord Board
Post by: RB on March 05, 2018, 11:05:29 AM
Hi Simon.
The power supply may be ok for testing anyway...
You have a lot to do before anything has to be exact...if then.
on the 50 pair...I think you need to look at one of the station sockets.
The ACTUAL tip and ring are the lines incoming to the board, and shud not be all tied together.
it wont hurt, much. you will just have one set of inputs instead of a bunch.
what you need to look for, is the other tip and ring on the station sockets, "if they are the same as on a 555", will be 4 contacts.
two are the tip and ring lines that are actual contacts on the socket.
the other two, will be switched inpower and ground. these will be tied together for all stations.
these second two, will be a switch contact that supplies + and - when the socket is vacant.
That's what goes out to the stations.
When the plug is inserted, it opens these contacts, and the cord pair supplies the power.
Title: Re: Powering up a 557A Cord Board
Post by: trainman on April 25, 2018, 04:27:18 PM
SD-65714-01 is the schematics for the 557a. It is on the TCI library, thats where i found a copy is. Its just hard for me on the mobile phone to copy and paste the link.

If you search within the Bruce Crawford Switching Library, you will find it.

Tony
Title: Re: Powering up a 557A Cord Board
Post by: trainman on April 25, 2018, 05:32:22 PM
http://www.telephonecollectors.info/index.php/browse/bc-switching-library/western-electric

At least three or 4 documents on the 557 on this page.
Title: Re: Powering up a 557A Cord Board
Post by: trainman on April 25, 2018, 05:34:31 PM
RB, the 557 behaves a little differently that a 555.
Title: Re: Powering up a 557A Cord Board
Post by: RB on April 25, 2018, 05:47:01 PM
not surprised... the ONLY thing I have found consistent with phones, is DIFFERENCES lol
Title: Re: Powering up a 557A Cord Board
Post by: trainman on April 25, 2018, 07:45:11 PM
Try this. Remember, the power and ringing current were sent over on cable pairs. So, more connections were requires since small quage wire was used.

In the battery section on the terminal board, connect a 20 quage wire from your power supply -24v to terminals 5, 11, and 16.

In the Ground section, connect a 18 guage wire from the ground which is market +24v to terminal 16.  If that doesnt work, we need to jumper some terminals on the ground side, but i dont have the schematic in front of me

Try connecting a phone to one station line and another phone to another station line. You should get lights amd relays clicking when you pick up the receiver.

The ringing supply should be marked GEN. Again, i need to go back to the schematic to find the terminas.
Title: Re: Powering up a 557A Cord Board
Post by: trainman on April 26, 2018, 10:52:30 AM
regarding supply voltage. these were built to operate on a range of voltages. as low as 16v to a max of 52v. if the power was sent form the telco CO, it was 48v. this one was used on 48v as evidenced by the 48v lamps found in it. the key system power supplies used 24v. it will work on 24v, but the bulbs will be dim on 48v. the bulbs coud be changed, but its getting harder to find them, as i think no one is making the telephone slide base bulbs anymore. LED subs are made, but expensive.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on June 16, 2018, 01:00:46 AM
Life got in the way of pet projects so I'm finally back to the 557 project.

I have made good progress. I found a 48v 100mA power supply and tied that in to the bat terminals. I then tied in dial tone to the first trunk and two Model 500 phones on two station lines.  Thus far I can answer the trunk, transfer the call from the outside to a station phone and connect two station phones. Things I can't seem to get it to do, buzz when there is an inbound call.  Get the lights to light up indicating one of the stations has picked up to make a call and ring a station by poshing the button.  Another odd thing is that I have a Panasonic TA-824 switch. The board is getting the DT from the block which is not going through the switch.  When I dial on the board all the phones ring. Also, the mic in the handset gets warm. On a side note I put a couple of Automatic Electric Type 80 phones on it and they did not work at all.

Just for fun I put the second trunk on and extension in the switch. This has the same results as above with the addition of the light when a call comes in doesn't light, the light does light when I get a call from an outside line. 

Anyone have any thought about getting it to buzz and lights to light?
Title: Re: Powering up a 557A Cord Board
Post by: RB on June 18, 2018, 04:08:02 PM
Simon.
I do not think your board will BUZZ on an incoming call.
That is a trunk function, and I don't think trunks buzz, they are self contained, with a light.
the buzzer is for station calls to the board. I believe, anyway.
The lights, I am not sure of, as my 555, lights work differently.
I think one is for busy testing, and the other, lights when one party hangs up, I believe.
To ring a station, plug in the right cord, and press the ring button. it shud ring, if the switches are turned on.
what is supplying dial tone?
do not continue to use the phone with the mic getting hot, it will fail something if used for long.
You have some more homework to do.
These boards were made to work with not all phones, just the ones supplied with the system. so differences will be found.
I could be wrong there, but I have the same probs mixin different phones together.
The batt connections are :
Batt1 to pins 1,4,5-10
Batt2 to pins 11-13.
That shud be all primary power needed.
Ringing a line, will require a ring power supply. I don't think they were installed in the board.
you can wire in a generator, and test that way.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on June 25, 2018, 07:25:35 PM
Hello RB,

Thanks for the reply.

Ok that would explain the not ringing on the trunk. The light does come on.  I checked some of the wiring and I think I was passing voltage where it shouldn't be so the mic isn't  getting warm any more.  I have gotten a few lights to light in the cord units but not when you pick up one of the handsets.  Also, I found one wire that is acting like a ground start for making a call between extensions.  When I tie it in to the negative side of the power supply  I can connect the two station phones together, but, none of the lights work. When I touch  the wire to the negative  or the frame the phones will connect and stay that way until i close the call. on the board.

I will say I'm having quite a bit of fun trying to figure it all out.
Title: Re: Powering up a 557A Cord Board
Post by: poplar1 on June 26, 2018, 04:00:07 AM
I have used phoneco-installed 557B and 555: Both rang on incoming trunk calls. I would assume 557A should also ring on trunk calls. Otherwise, how would you know there was an incoming trunk call if you were not sitting in front of the board?
Title: Re: Powering up a 557A Cord Board
Post by: RB on June 26, 2018, 10:46:02 AM
Agreed, Poplar1.
There would need to be an audible indication of an incoming call.
However, I do not believe it was the same BUZZ circuit as the extensions...
The schematic does not describe trunk inputs to the buzz circuit. but I may be missing a part.
The schematics are broken into pieces, and without having them all lased together, it is hard to see everything at the same time.
Simon, the lights, were used to indicate various things.
Some, were just hangin on the line, waitin to be lit.
others, needed a voltage reversal to light.
These were governed, i believe, by the supervisor options installed on the boards.
So, some lit under normal situations, and others did not.
Due to the trunk versus extension differences.
and, you had to plug the cords in in the correct order, or no lites.
My 555 acts that way, one lite lites for extensions, and the other only on trunk functions...i believe.
As for your mystery wire Simon, try to find where it comes from, then we can follow the schematics to correct it
Title: Re: Powering up a 557A Cord Board
Post by: RB on June 26, 2018, 11:49:23 AM
I found an AUX signal circuit, it may be what is used to provide RING for incoming trunk calls.
I have not messed with this circuit, so...guessing here.
so, generally speaking, we got two different animals in the same box.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on June 26, 2018, 09:24:36 PM
WOW! that is just too cool! 

Yes, I believe the 555 is a standard PBX board that is used in an office to transfer calls around to station lines.  the 557 was for a call center so customers cold call in and have the operator  answer the call as a "secretary" for the subscribing customer.  this is what most of the board is set up for. In addition the 557 could ace like an office PBX with a small number of station lines.  DFrom what I can tell the 555 and 557 are almost identical at that point.  Does that sound correct to you?

I did find a BSP on the 555. 
Title: Re: Powering up a 557A Cord Board
Post by: poplar1 on June 26, 2018, 11:04:01 PM
557A has station lines.The more common 557B does not.
Title: Re: Powering up a 557A Cord Board
Post by: simonwolfe on June 26, 2018, 11:26:04 PM
Ah, OK.  I wasn't overly sure about that.  Thanks!
Title: Re: Powering up a 557A Cord Board
Post by: poplar1 on June 27, 2018, 08:53:18 AM
Also, the 555 and the 557A have cord pairs. The 557B uses single cords since there are no stations that need to be connected to a trunk.

At the answering bureau where I worked, there were three 557Bs. There was also a 1A2 Key System with several 830 sets (9-line) with appearances of the same trunks that appeared on the 557Bs. Of course, you couldn't access the secretarial lines from the 830 sets.
Title: Re: Powering up a 557A Cord Board
Post by: RB on June 27, 2018, 09:53:45 AM
Quote from: simonwolfe on June 26, 2018, 09:24:36 PM
WOW! that is just too cool! 

Yes, I believe the 555 is a standard PBX board that is used in an office to transfer calls around to station lines.  the 557 was for a call center so customers cold call in and have the operator  answer the call as a "secretary" for the subscribing customer.  this is what most of the board is set up for. In addition the 557 could ace like an office PBX with a small number of station lines.  DFrom what I can tell the 555 and 557 are almost identical at that point.  Does that sound correct to you?

I did find a BSP on the 555.
Simon, from what I can tell, the 555 and 557A are almost identical in the basic construction.
The options, of course, varied with each installation. But the pages of the schematics from both look the same.
You will need at some point, to determine what supervisory options are in place on that board.
That will help with understanding how the lights work.
Or, you may be lucky, and they just work...