Author Topic: Powering up a 557A Cord Board  (Read 1257 times)

Offline HarrySmith

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Re: Powering up a 557A Cord Board
« Reply #15 on: March 02, 2018, 10:56:11 AM »
I have attached a circuit diagram from my stash of 555 documents.
Harry Smith
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Offline simonwolfe

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Re: Powering up a 557A Cord Board
« Reply #16 on: March 03, 2018, 08:27:25 AM »
I have attached a circuit diagram from my stash of 555 documents.

Cool, Thank you!

Offline simonwolfe

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Re: Powering up a 557A Cord Board
« Reply #17 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!

Offline RB

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Re: Powering up a 557A Cord Board
« Reply #18 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.

Offline trainman

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Re: Powering up a 557A Cord Board
« Reply #19 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

Offline trainman

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Re: Powering up a 557A Cord Board
« Reply #20 on: April 25, 2018, 05:32:22 PM »

Offline trainman

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Re: Powering up a 557A Cord Board
« Reply #21 on: April 25, 2018, 05:34:31 PM »
RB, the 557 behaves a little differently that a 555.

Offline RB

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Re: Powering up a 557A Cord Board
« Reply #22 on: April 25, 2018, 05:47:01 PM »
not surprised... the ONLY thing I have found consistent with phones, is DIFFERENCES lol

Offline trainman

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Re: Powering up a 557A Cord Board
« Reply #23 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.

Offline trainman

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Re: Powering up a 557A Cord Board
« Reply #24 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.

Offline simonwolfe

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Re: Powering up a 557A Cord Board
« Reply #25 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?

Offline RB

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Re: Powering up a 557A Cord Board
« Reply #26 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.

Offline simonwolfe

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Re: Powering up a 557A Cord Board
« Reply #27 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.

Offline poplar1

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Re: Powering up a 557A Cord Board
« Reply #28 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?
« Last Edit: June 26, 2018, 04:07:33 AM by poplar1 »
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Offline RB

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Re: Powering up a 557A Cord Board
« Reply #29 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